From b81795728114d8a05181d3beab0cb972be20dbad Mon Sep 17 00:00:00 2001
From: jto <boudhevil@gmail.com>
Date: Tue, 23 Jul 2024 11:58:28 +0200
Subject: [PATCH 01/26] [Flink] Set return type of bounded sources

---
 .../runners/flink/FlinkStreamingTransformTranslators.java   | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingTransformTranslators.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingTransformTranslators.java
index f9089d11a25e..2321306da070 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingTransformTranslators.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingTransformTranslators.java
@@ -389,6 +389,9 @@ public void translateNode(
               new SerializablePipelineOptions(context.getPipelineOptions()),
               parallelism);
 
+      TypeInformation<WindowedValue<T>> typeInfo =
+          context.getTypeInfo(output);
+
       DataStream<WindowedValue<T>> source;
       try {
         source =
@@ -396,7 +399,8 @@ public void translateNode(
                 .getExecutionEnvironment()
                 .fromSource(
                     flinkBoundedSource, WatermarkStrategy.noWatermarks(), fullName, outputTypeInfo)
-                .uid(fullName);
+                .uid(fullName)
+                .returns(typeInfo);
       } catch (Exception e) {
         throw new RuntimeException("Error while translating BoundedSource: " + rawSource, e);
       }

From ca9630ac0a604194967bac723a6abfc88a86ce13 Mon Sep 17 00:00:00 2001
From: jto <boudhevil@gmail.com>
Date: Tue, 23 Jul 2024 17:58:29 +0200
Subject: [PATCH 02/26] [Flink] Use a lazy split enumerator for bounded sources

[Flink] fix lazy enumerator package
---
 .../streaming/io/source/FlinkSource.java      |  21 +-
 .../LazyFlinkSourceSplitEnumerator.java       | 180 ++++++++++++++++++
 .../bounded/FlinkBoundedSourceReader.java     |   6 +
 3 files changed, 202 insertions(+), 5 deletions(-)
 create mode 100644 runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/io/source/LazyFlinkSourceSplitEnumerator.java

diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/io/source/FlinkSource.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/io/source/FlinkSource.java
index 506b651da68f..3e5d68df1df7 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/io/source/FlinkSource.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/io/source/FlinkSource.java
@@ -118,8 +118,20 @@ public Boundedness getBoundedness() {
   @Override
   public SplitEnumerator<FlinkSourceSplit<T>, Map<Integer, List<FlinkSourceSplit<T>>>>
       createEnumerator(SplitEnumeratorContext<FlinkSourceSplit<T>> enumContext) throws Exception {
-    return new FlinkSourceSplitEnumerator<>(
-        enumContext, beamSource, serializablePipelineOptions.get(), numSplits);
+
+    if(boundedness == Boundedness.BOUNDED) {
+      return new LazyFlinkSourceSplitEnumerator<>(
+        enumContext,
+        beamSource,
+        serializablePipelineOptions.get(),
+        numSplits);
+    } else {
+      return new FlinkSourceSplitEnumerator<>(
+        enumContext,
+        beamSource,
+        serializablePipelineOptions.get(),
+        numSplits);
+    }
   }
 
   @Override
@@ -128,9 +140,8 @@ public Boundedness getBoundedness() {
           SplitEnumeratorContext<FlinkSourceSplit<T>> enumContext,
           Map<Integer, List<FlinkSourceSplit<T>>> checkpoint)
           throws Exception {
-    FlinkSourceSplitEnumerator<T> enumerator =
-        new FlinkSourceSplitEnumerator<>(
-            enumContext, beamSource, serializablePipelineOptions.get(), numSplits);
+    SplitEnumerator<FlinkSourceSplit<T>, Map<Integer, List<FlinkSourceSplit<T>>>> enumerator =
+      createEnumerator(enumContext);
     checkpoint.forEach(
         (subtaskId, splitsForSubtask) -> enumerator.addSplitsBack(splitsForSubtask, subtaskId));
     return enumerator;
diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/io/source/LazyFlinkSourceSplitEnumerator.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/io/source/LazyFlinkSourceSplitEnumerator.java
new file mode 100644
index 000000000000..fdd14025a95a
--- /dev/null
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/io/source/LazyFlinkSourceSplitEnumerator.java
@@ -0,0 +1,180 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.beam.runners.flink.translation.wrappers.streaming.io.source;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+
+import javax.annotation.Nullable;
+
+import org.apache.beam.runners.flink.FlinkPipelineOptions;
+import org.apache.beam.runners.flink.translation.wrappers.streaming.io.source.FlinkSourceSplit;
+import org.apache.beam.runners.flink.translation.wrappers.streaming.io.source.FlinkSourceSplitEnumerator;
+import org.apache.beam.runners.flink.translation.wrappers.streaming.io.source.compat.SplitEnumeratorCompat;
+import org.apache.beam.sdk.io.BoundedSource;
+import org.apache.beam.sdk.io.FileBasedSource;
+import org.apache.beam.sdk.io.Source;
+import org.apache.beam.sdk.io.UnboundedSource;
+import org.apache.beam.sdk.options.PipelineOptions;
+import org.apache.flink.api.connector.source.SplitEnumeratorContext;
+import org.apache.flink.api.connector.source.SplitsAssignment;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * A Flink {@link org.apache.flink.api.connector.source.SplitEnumerator SplitEnumerator}
+ * implementation that holds a Beam {@link Source} and does the following:
+ *
+ * <ul>
+ *   <li>Split the Beam {@link Source} to desired number of splits.
+ *   <li>Lazily assign the splits to the Flink Source Reader.
+ * </ul>
+ *
+ * @param <T> The output type of the encapsulated Beam {@link Source}.
+ */
+public class LazyFlinkSourceSplitEnumerator<T>
+    implements SplitEnumeratorCompat<FlinkSourceSplit<T>, Map<Integer, List<FlinkSourceSplit<T>>>> {
+  private static final Logger LOG = LoggerFactory.getLogger(LazyFlinkSourceSplitEnumerator.class);
+  private final SplitEnumeratorContext<FlinkSourceSplit<T>> context;
+  private final Source<T> beamSource;
+  private final PipelineOptions pipelineOptions;
+  private final int numSplits;
+  private final List<FlinkSourceSplit<T>> pendingSplits;
+
+  public LazyFlinkSourceSplitEnumerator(
+      SplitEnumeratorContext<FlinkSourceSplit<T>> context,
+      Source<T> beamSource,
+      PipelineOptions pipelineOptions,
+      int numSplits) {
+    this.context = context;
+    this.beamSource = beamSource;
+    this.pipelineOptions = pipelineOptions;
+    this.numSplits = numSplits;
+    this.pendingSplits = new ArrayList<>(numSplits);
+  }
+
+  @Override
+  public void start() {
+    try {
+      LOG.info("Starting source {}", beamSource);
+      List<? extends Source<T>> beamSplitSourceList = splitBeamSource();
+      int i = 0;
+      for (Source<T> beamSplitSource : beamSplitSourceList) {
+        pendingSplits.add(new FlinkSourceSplit<>(i, beamSplitSource));
+        i++;
+      }
+    } catch (Exception e) {
+      throw new RuntimeException(e);
+    }
+  }
+
+  @Override
+  public void handleSplitRequest(int subtask, @Nullable String hostname) {
+    if (!context.registeredReaders().containsKey(subtask)) {
+        // reader failed between sending the request and now. skip this request.
+        return;
+    }
+
+    if (LOG.isInfoEnabled()) {
+        final String hostInfo =
+                hostname == null ? "(no host locality info)" : "(on host '" + hostname + "')";
+        LOG.info("Subtask {} {} is requesting a file source split", subtask, hostInfo);
+    }
+
+    if (!pendingSplits.isEmpty()) {
+        final FlinkSourceSplit<T> split = pendingSplits.remove(pendingSplits.size() - 1);
+        context.assignSplit(split, subtask);
+        LOG.info("Assigned split to subtask {} : {}", subtask, split);
+    } else {
+        context.signalNoMoreSplits(subtask);
+        LOG.info("No more splits available for subtask {}", subtask);
+    }
+  }
+
+  @Override
+  public void addSplitsBack(List<FlinkSourceSplit<T>> splits, int subtaskId) {
+    LOG.info("Adding splits {} back from subtask {}", splits, subtaskId);
+    pendingSplits.addAll(splits);
+  }
+
+  @Override
+  public void addReader(int subtaskId) {
+    // this source is purely lazy-pull-based, nothing to do upon registration
+  }
+
+  @Override
+  public Map<Integer, List<FlinkSourceSplit<T>>> snapshotState(long checkpointId) throws Exception {
+    LOG.info("Taking snapshot for checkpoint {}", checkpointId);
+    return snapshotState();
+  }
+
+  @Override
+  public Map<Integer, List<FlinkSourceSplit<T>>> snapshotState() throws Exception {
+    // For type compatibility reasons, we return a Map but we do not actually care about the key
+    Map<Integer, List<FlinkSourceSplit<T>>> state = new HashMap<>(1);
+    state.put(1, pendingSplits);
+    return state;
+  }
+
+  @Override
+  public void close() throws IOException {
+    // NoOp
+  }
+
+  private long getDesiredSizeBytes(int numSplits, BoundedSource<T> boundedSource) throws Exception {
+    long totalSize = boundedSource.getEstimatedSizeBytes(pipelineOptions);
+    long defaultSplitSize = totalSize / numSplits;
+    long maxSplitSize = 0;
+    if (pipelineOptions != null) {
+      maxSplitSize = pipelineOptions.as(FlinkPipelineOptions.class).getFileInputSplitMaxSizeMB();
+    }
+    if (beamSource instanceof FileBasedSource && maxSplitSize > 0) {
+      // Most of the time parallelism is < number of files in source.
+      // Each file becomes a unique split which commonly create skew.
+      // This limits the size of splits to reduce skew.
+      return Math.min(defaultSplitSize, maxSplitSize * 1024 * 1024);
+    } else {
+      return defaultSplitSize;
+    }
+  }
+
+  // -------------- Private helper methods ----------------------
+  private List<? extends Source<T>> splitBeamSource() throws Exception {
+    if (beamSource instanceof BoundedSource) {
+      BoundedSource<T> boundedSource = (BoundedSource<T>) beamSource;
+      long desiredSizeBytes = getDesiredSizeBytes(numSplits, boundedSource);
+      List<? extends BoundedSource<T>> splits =
+          ((BoundedSource<T>) beamSource).split(desiredSizeBytes, pipelineOptions);
+      LOG.info("Split bounded source {} in {} splits", beamSource, splits.size());
+      return splits;
+    } else if (beamSource instanceof UnboundedSource) {
+      List<? extends UnboundedSource<T, ?>> splits =
+          ((UnboundedSource<T, ?>) beamSource).split(numSplits, pipelineOptions);
+      LOG.info("Split source {} to {} splits", beamSource, splits);
+      return splits;
+    } else {
+      throw new IllegalStateException("Unknown source type " + beamSource.getClass());
+    }
+  }
+}
diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/io/source/bounded/FlinkBoundedSourceReader.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/io/source/bounded/FlinkBoundedSourceReader.java
index e4bd4496ae90..d87d84d93dc2 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/io/source/bounded/FlinkBoundedSourceReader.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/io/source/bounded/FlinkBoundedSourceReader.java
@@ -100,6 +100,11 @@ protected FlinkBoundedSourceReader(
   @Override
   public InputStatus pollNext(ReaderOutput<WindowedValue<T>> output) throws Exception {
     checkExceptionAndMaybeThrow();
+
+    if(currentReader == null && currentSplitId == -1) {
+      context.sendSplitRequest();
+    }
+
     if (currentReader == null && !moveToNextNonEmptyReader()) {
       // Nothing to read for now.
       if (noMoreSplits()) {
@@ -137,6 +142,7 @@ public InputStatus pollNext(ReaderOutput<WindowedValue<T>> output) throws Except
         LOG.debug("Finished reading from {}", currentSplitId);
         currentReader = null;
         currentSplitId = -1;
+        context.sendSplitRequest();
       }
       // Always return MORE_AVAILABLE here regardless of the availability of next record. If there
       // is no more

From 866fb780192f4d01f3a886806b45196ae0795d92 Mon Sep 17 00:00:00 2001
From: jto <boudhevil@gmail.com>
Date: Mon, 19 Aug 2024 10:01:41 +0200
Subject: [PATCH 03/26] [Flink] Default to maxParallelism = parallelism in
 batch

---
 .../beam/runners/flink/FlinkExecutionEnvironments.java     | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkExecutionEnvironments.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkExecutionEnvironments.java
index 102340329b6b..1ef5da6c124d 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkExecutionEnvironments.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkExecutionEnvironments.java
@@ -237,6 +237,13 @@ public static StreamExecutionEnvironment createStreamExecutionEnvironment(
     flinkStreamEnv.setParallelism(parallelism);
     if (options.getMaxParallelism() > 0) {
       flinkStreamEnv.setMaxParallelism(options.getMaxParallelism());
+    } else if(!options.isStreaming()) {
+      // In Flink maxParallelism defines the number of keyGroups.
+      // (see https://github.com/apache/flink/blob/e9dd4683f758b463d0b5ee18e49cecef6a70c5cf/flink-runtime/src/main/java/org/apache/flink/runtime/state/KeyGroupRangeAssignment.java#L76)
+      // The default value (parallelism * 1.5)
+      // (see https://github.com/apache/flink/blob/e9dd4683f758b463d0b5ee18e49cecef6a70c5cf/flink-runtime/src/main/java/org/apache/flink/runtime/state/KeyGroupRangeAssignment.java#L137-L147)
+      // create a lot of skew so we force maxParallelism = parallelism in Batch mode.
+      flinkStreamEnv.setMaxParallelism(parallelism);
     }
     // set parallelism in the options (required by some execution code)
     options.setParallelism(parallelism);

From 5c89f15061ffaa6f4a5580948fe637f62dea89f2 Mon Sep 17 00:00:00 2001
From: jto <boudhevil@gmail.com>
Date: Tue, 20 Aug 2024 11:43:48 +0200
Subject: [PATCH 04/26] [Flink] Avoid re-serializing trigger on every element

---
 .../core/GroupAlsoByWindowViaWindowSetNewDoFn.java        | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/runners/core-java/src/main/java/org/apache/beam/runners/core/GroupAlsoByWindowViaWindowSetNewDoFn.java b/runners/core-java/src/main/java/org/apache/beam/runners/core/GroupAlsoByWindowViaWindowSetNewDoFn.java
index 0759487565b0..853a182b2ca0 100644
--- a/runners/core-java/src/main/java/org/apache/beam/runners/core/GroupAlsoByWindowViaWindowSetNewDoFn.java
+++ b/runners/core-java/src/main/java/org/apache/beam/runners/core/GroupAlsoByWindowViaWindowSetNewDoFn.java
@@ -18,6 +18,8 @@
 package org.apache.beam.runners.core;
 
 import java.util.Collection;
+
+import org.apache.beam.model.pipeline.v1.RunnerApi;
 import org.apache.beam.runners.core.triggers.ExecutableTriggerStateMachine;
 import org.apache.beam.runners.core.triggers.TriggerStateMachines;
 import org.apache.beam.sdk.transforms.DoFn;
@@ -41,6 +43,7 @@ public class GroupAlsoByWindowViaWindowSetNewDoFn<
     extends DoFn<RinT, KV<K, OutputT>> {
 
   private static final long serialVersionUID = 1L;
+  private final RunnerApi.Trigger triggerProto;
 
   public static <K, InputT, OutputT, W extends BoundedWindow>
       DoFn<KeyedWorkItem<K, InputT>, KV<K, OutputT>> create(
@@ -86,6 +89,7 @@ public GroupAlsoByWindowViaWindowSetNewDoFn(
     this.windowingStrategy = noWildcard;
     this.reduceFn = reduceFn;
     this.stateInternalsFactory = stateInternalsFactory;
+    this.triggerProto = TriggerTranslation.toProto(windowingStrategy.getTrigger());
   }
 
   private OutputWindowedValue<KV<K, OutputT>> outputWindowedValue() {
@@ -123,9 +127,7 @@ public void processElement(ProcessContext c) throws Exception {
         new ReduceFnRunner<>(
             key,
             windowingStrategy,
-            ExecutableTriggerStateMachine.create(
-                TriggerStateMachines.stateMachineForTrigger(
-                    TriggerTranslation.toProto(windowingStrategy.getTrigger()))),
+            ExecutableTriggerStateMachine.create(TriggerStateMachines.stateMachineForTrigger(triggerProto)),
             stateInternals,
             timerInternals,
             outputWindowedValue(),

From f2b2eb771170c245b1019687d46ed8628c7cb44b Mon Sep 17 00:00:00 2001
From: jto <boudhevil@gmail.com>
Date: Tue, 20 Aug 2024 11:23:50 +0200
Subject: [PATCH 05/26] [Flink] Avoid re-evaluating options every time a new
 state is stored

---
 .../types/CoderTypeSerializer.java            | 19 ++---
 .../types/CoderTypeSerializer.java            | 19 ++---
 .../streaming/state/FlinkStateInternals.java  | 75 ++++++++++---------
 3 files changed, 50 insertions(+), 63 deletions(-)

diff --git a/runners/flink/1.15/src/main/java/org/apache/beam/runners/flink/translation/types/CoderTypeSerializer.java b/runners/flink/1.15/src/main/java/org/apache/beam/runners/flink/translation/types/CoderTypeSerializer.java
index 956aad428d8b..6c21ea8edc00 100644
--- a/runners/flink/1.15/src/main/java/org/apache/beam/runners/flink/translation/types/CoderTypeSerializer.java
+++ b/runners/flink/1.15/src/main/java/org/apache/beam/runners/flink/translation/types/CoderTypeSerializer.java
@@ -50,23 +50,16 @@ public class CoderTypeSerializer<T> extends TypeSerializer<T> {
 
   private final Coder<T> coder;
 
-  /**
-   * {@link SerializablePipelineOptions} deserialization will cause {@link
-   * org.apache.beam.sdk.io.FileSystems} registration needed for {@link
-   * org.apache.beam.sdk.transforms.Reshuffle} translation.
-   */
-  private final SerializablePipelineOptions pipelineOptions;
-
   private final boolean fasterCopy;
 
   public CoderTypeSerializer(Coder<T> coder, SerializablePipelineOptions pipelineOptions) {
+    this(coder, Preconditions.checkNotNull(pipelineOptions).get().as(FlinkPipelineOptions.class).getFasterCopy());
+  }
+
+  public CoderTypeSerializer(Coder<T> coder, boolean fasterCopy) {
     Preconditions.checkNotNull(coder);
-    Preconditions.checkNotNull(pipelineOptions);
     this.coder = coder;
-    this.pipelineOptions = pipelineOptions;
-
-    FlinkPipelineOptions options = pipelineOptions.get().as(FlinkPipelineOptions.class);
-    this.fasterCopy = options.getFasterCopy();
+    this.fasterCopy = fasterCopy;
   }
 
   @Override
@@ -76,7 +69,7 @@ public boolean isImmutableType() {
 
   @Override
   public CoderTypeSerializer<T> duplicate() {
-    return new CoderTypeSerializer<>(coder, pipelineOptions);
+    return new CoderTypeSerializer<>(coder, fasterCopy);
   }
 
   @Override
diff --git a/runners/flink/1.17/src/main/java/org/apache/beam/runners/flink/translation/types/CoderTypeSerializer.java b/runners/flink/1.17/src/main/java/org/apache/beam/runners/flink/translation/types/CoderTypeSerializer.java
index 0f87271a9779..911dd3185adf 100644
--- a/runners/flink/1.17/src/main/java/org/apache/beam/runners/flink/translation/types/CoderTypeSerializer.java
+++ b/runners/flink/1.17/src/main/java/org/apache/beam/runners/flink/translation/types/CoderTypeSerializer.java
@@ -47,23 +47,16 @@ public class CoderTypeSerializer<T> extends TypeSerializer<T> {
 
   private final Coder<T> coder;
 
-  /**
-   * {@link SerializablePipelineOptions} deserialization will cause {@link
-   * org.apache.beam.sdk.io.FileSystems} registration needed for {@link
-   * org.apache.beam.sdk.transforms.Reshuffle} translation.
-   */
-  private final SerializablePipelineOptions pipelineOptions;
-
   private final boolean fasterCopy;
 
   public CoderTypeSerializer(Coder<T> coder, SerializablePipelineOptions pipelineOptions) {
+    this(coder, Preconditions.checkNotNull(pipelineOptions).get().as(FlinkPipelineOptions.class).getFasterCopy());
+  }
+
+  public CoderTypeSerializer(Coder<T> coder, boolean fasterCopy) {
     Preconditions.checkNotNull(coder);
-    Preconditions.checkNotNull(pipelineOptions);
     this.coder = coder;
-    this.pipelineOptions = pipelineOptions;
-
-    FlinkPipelineOptions options = pipelineOptions.get().as(FlinkPipelineOptions.class);
-    this.fasterCopy = options.getFasterCopy();
+    this.fasterCopy = fasterCopy;
   }
 
   @Override
@@ -73,7 +66,7 @@ public boolean isImmutableType() {
 
   @Override
   public CoderTypeSerializer<T> duplicate() {
-    return new CoderTypeSerializer<>(coder, pipelineOptions);
+    return new CoderTypeSerializer<>(coder, fasterCopy);
   }
 
   @Override
diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/state/FlinkStateInternals.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/state/FlinkStateInternals.java
index 205270c22332..bb662669179d 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/state/FlinkStateInternals.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/state/FlinkStateInternals.java
@@ -33,6 +33,7 @@
 import org.apache.beam.runners.core.StateNamespaces;
 import org.apache.beam.runners.core.StateTag;
 import org.apache.beam.runners.core.construction.SerializablePipelineOptions;
+import org.apache.beam.runners.flink.FlinkPipelineOptions;
 import org.apache.beam.runners.flink.translation.types.CoderTypeSerializer;
 import org.apache.beam.runners.flink.translation.wrappers.streaming.FlinkKeyUtils;
 import org.apache.beam.sdk.coders.Coder;
@@ -162,7 +163,7 @@ public String toString() {
   // State to persist combined watermark holds for all keys of this partition
   private final MapStateDescriptor<String, Instant> watermarkHoldStateDescriptor;
 
-  private final SerializablePipelineOptions pipelineOptions;
+  private final boolean fasterCopy;
 
   public FlinkStateInternals(
       KeyedStateBackend<ByteBuffer> flinkStateBackend,
@@ -171,13 +172,13 @@ public FlinkStateInternals(
       throws Exception {
     this.flinkStateBackend = Objects.requireNonNull(flinkStateBackend);
     this.keyCoder = Objects.requireNonNull(keyCoder);
+    this.fasterCopy = pipelineOptions.get().as(FlinkPipelineOptions.class).getFasterCopy();
+
     watermarkHoldStateDescriptor =
         new MapStateDescriptor<>(
             "watermark-holds",
             StringSerializer.INSTANCE,
-            new CoderTypeSerializer<>(InstantCoder.of(), pipelineOptions));
-    this.pipelineOptions = pipelineOptions;
-
+            new CoderTypeSerializer<>(InstantCoder.of(), fasterCopy));
     restoreWatermarkHoldsView();
   }
 
@@ -241,7 +242,7 @@ private FlinkStateBinder(StateNamespace namespace, StateContext<?> stateContext)
     public <T2> ValueState<T2> bindValue(
         String id, StateSpec<ValueState<T2>> spec, Coder<T2> coder) {
       FlinkValueState<T2> valueState =
-          new FlinkValueState<>(flinkStateBackend, id, namespace, coder, pipelineOptions);
+          new FlinkValueState<>(flinkStateBackend, id, namespace, coder, fasterCopy);
       collectGlobalWindowStateDescriptor(
           valueState.flinkStateDescriptor,
           valueState.namespace.stringKey(),
@@ -252,7 +253,7 @@ public <T2> ValueState<T2> bindValue(
     @Override
     public <T2> BagState<T2> bindBag(String id, StateSpec<BagState<T2>> spec, Coder<T2> elemCoder) {
       FlinkBagState<T2> bagState =
-          new FlinkBagState<>(flinkStateBackend, id, namespace, elemCoder, pipelineOptions);
+          new FlinkBagState<>(flinkStateBackend, id, namespace, elemCoder, fasterCopy);
       collectGlobalWindowStateDescriptor(
           bagState.flinkStateDescriptor, bagState.namespace.stringKey(), StringSerializer.INSTANCE);
       return bagState;
@@ -261,7 +262,7 @@ public <T2> BagState<T2> bindBag(String id, StateSpec<BagState<T2>> spec, Coder<
     @Override
     public <T2> SetState<T2> bindSet(String id, StateSpec<SetState<T2>> spec, Coder<T2> elemCoder) {
       FlinkSetState<T2> setState =
-          new FlinkSetState<>(flinkStateBackend, id, namespace, elemCoder, pipelineOptions);
+          new FlinkSetState<>(flinkStateBackend, id, namespace, elemCoder, fasterCopy);
       collectGlobalWindowStateDescriptor(
           setState.flinkStateDescriptor, setState.namespace.stringKey(), StringSerializer.INSTANCE);
       return setState;
@@ -275,7 +276,7 @@ public <KeyT, ValueT> MapState<KeyT, ValueT> bindMap(
         Coder<ValueT> mapValueCoder) {
       FlinkMapState<KeyT, ValueT> mapState =
           new FlinkMapState<>(
-              flinkStateBackend, id, namespace, mapKeyCoder, mapValueCoder, pipelineOptions);
+              flinkStateBackend, id, namespace, mapKeyCoder, mapValueCoder, fasterCopy);
       collectGlobalWindowStateDescriptor(
           mapState.flinkStateDescriptor, mapState.namespace.stringKey(), StringSerializer.INSTANCE);
       return mapState;
@@ -285,7 +286,7 @@ public <KeyT, ValueT> MapState<KeyT, ValueT> bindMap(
     public <T> OrderedListState<T> bindOrderedList(
         String id, StateSpec<OrderedListState<T>> spec, Coder<T> elemCoder) {
       FlinkOrderedListState<T> flinkOrderedListState =
-          new FlinkOrderedListState<>(flinkStateBackend, id, namespace, elemCoder, pipelineOptions);
+          new FlinkOrderedListState<>(flinkStateBackend, id, namespace, elemCoder, fasterCopy);
       collectGlobalWindowStateDescriptor(
           flinkOrderedListState.flinkStateDescriptor,
           flinkOrderedListState.namespace.stringKey(),
@@ -311,7 +312,7 @@ public <InputT, AccumT, OutputT> CombiningState<InputT, AccumT, OutputT> bindCom
         Combine.CombineFn<InputT, AccumT, OutputT> combineFn) {
       FlinkCombiningState<Object, InputT, AccumT, OutputT> combiningState =
           new FlinkCombiningState<>(
-              flinkStateBackend, id, combineFn, namespace, accumCoder, pipelineOptions);
+              flinkStateBackend, id, combineFn, namespace, accumCoder, fasterCopy);
       collectGlobalWindowStateDescriptor(
           combiningState.flinkStateDescriptor,
           combiningState.namespace.stringKey(),
@@ -334,7 +335,7 @@ CombiningState<InputT, AccumT, OutputT> bindCombiningWithContext(
               namespace,
               accumCoder,
               CombineContextFactory.createFromStateContext(stateContext),
-              pipelineOptions);
+              fasterCopy);
       collectGlobalWindowStateDescriptor(
           combiningStateWithContext.flinkStateDescriptor,
           combiningStateWithContext.namespace.stringKey(),
@@ -380,14 +381,14 @@ private static class FlinkValueState<T> implements ValueState<T> {
         String stateId,
         StateNamespace namespace,
         Coder<T> coder,
-        SerializablePipelineOptions pipelineOptions) {
+        boolean fasterCopy) {
 
       this.namespace = namespace;
       this.stateId = stateId;
       this.flinkStateBackend = flinkStateBackend;
 
       flinkStateDescriptor =
-          new ValueStateDescriptor<>(stateId, new CoderTypeSerializer<>(coder, pipelineOptions));
+          new ValueStateDescriptor<>(stateId, new CoderTypeSerializer<>(coder, fasterCopy));
     }
 
     @Override
@@ -463,12 +464,12 @@ private static class FlinkOrderedListState<T> implements OrderedListState<T> {
         String stateId,
         StateNamespace namespace,
         Coder<T> coder,
-        SerializablePipelineOptions pipelineOptions) {
+        boolean fasterCopy) {
       this.namespace = namespace;
       this.flinkStateBackend = flinkStateBackend;
       this.flinkStateDescriptor =
           new ListStateDescriptor<>(
-              stateId, new CoderTypeSerializer<>(TimestampedValueCoder.of(coder), pipelineOptions));
+              stateId, new CoderTypeSerializer<>(TimestampedValueCoder.of(coder), fasterCopy));
     }
 
     @Override
@@ -586,14 +587,14 @@ private static class FlinkBagState<T> implements BagState<T> {
         String stateId,
         StateNamespace namespace,
         Coder<T> coder,
-        SerializablePipelineOptions pipelineOptions) {
+        boolean fasterCopy) {
 
       this.namespace = namespace;
       this.stateId = stateId;
       this.flinkStateBackend = flinkStateBackend;
       this.storesVoidValues = coder instanceof VoidCoder;
       this.flinkStateDescriptor =
-          new ListStateDescriptor<>(stateId, new CoderTypeSerializer<>(coder, pipelineOptions));
+          new ListStateDescriptor<>(stateId, new CoderTypeSerializer<>(coder, fasterCopy));
     }
 
     @Override
@@ -726,7 +727,7 @@ private static class FlinkCombiningState<K, InputT, AccumT, OutputT>
         Combine.CombineFn<InputT, AccumT, OutputT> combineFn,
         StateNamespace namespace,
         Coder<AccumT> accumCoder,
-        SerializablePipelineOptions pipelineOptions) {
+        boolean fasterCopy) {
 
       this.namespace = namespace;
       this.stateId = stateId;
@@ -735,7 +736,7 @@ private static class FlinkCombiningState<K, InputT, AccumT, OutputT>
 
       flinkStateDescriptor =
           new ValueStateDescriptor<>(
-              stateId, new CoderTypeSerializer<>(accumCoder, pipelineOptions));
+              stateId, new CoderTypeSerializer<>(accumCoder, fasterCopy));
     }
 
     @Override
@@ -891,7 +892,7 @@ private static class FlinkCombiningStateWithContext<K, InputT, AccumT, OutputT>
         StateNamespace namespace,
         Coder<AccumT> accumCoder,
         CombineWithContext.Context context,
-        SerializablePipelineOptions pipelineOptions) {
+        boolean fasterCopy) {
 
       this.namespace = namespace;
       this.stateId = stateId;
@@ -901,7 +902,7 @@ private static class FlinkCombiningStateWithContext<K, InputT, AccumT, OutputT>
 
       flinkStateDescriptor =
           new ValueStateDescriptor<>(
-              stateId, new CoderTypeSerializer<>(accumCoder, pipelineOptions));
+              stateId, new CoderTypeSerializer<>(accumCoder, fasterCopy));
     }
 
     @Override
@@ -1178,15 +1179,15 @@ private static class FlinkMapState<KeyT, ValueT> implements MapState<KeyT, Value
         StateNamespace namespace,
         Coder<KeyT> mapKeyCoder,
         Coder<ValueT> mapValueCoder,
-        SerializablePipelineOptions pipelineOptions) {
+        boolean fasterCopy) {
       this.namespace = namespace;
       this.stateId = stateId;
       this.flinkStateBackend = flinkStateBackend;
       this.flinkStateDescriptor =
           new MapStateDescriptor<>(
               stateId,
-              new CoderTypeSerializer<>(mapKeyCoder, pipelineOptions),
-              new CoderTypeSerializer<>(mapValueCoder, pipelineOptions));
+              new CoderTypeSerializer<>(mapKeyCoder, fasterCopy),
+              new CoderTypeSerializer<>(mapValueCoder, fasterCopy));
     }
 
     @Override
@@ -1402,14 +1403,14 @@ private static class FlinkSetState<T> implements SetState<T> {
         String stateId,
         StateNamespace namespace,
         Coder<T> coder,
-        SerializablePipelineOptions pipelineOptions) {
+        boolean fasterCopy) {
       this.namespace = namespace;
       this.stateId = stateId;
       this.flinkStateBackend = flinkStateBackend;
       this.flinkStateDescriptor =
           new MapStateDescriptor<>(
               stateId,
-              new CoderTypeSerializer<>(coder, pipelineOptions),
+              new CoderTypeSerializer<>(coder, fasterCopy),
               BooleanSerializer.INSTANCE);
     }
 
@@ -1571,12 +1572,12 @@ private void restoreWatermarkHoldsView() throws Exception {
   public static class EarlyBinder implements StateBinder {
 
     private final KeyedStateBackend keyedStateBackend;
-    private final SerializablePipelineOptions pipelineOptions;
+    private final Boolean fasterCopy;
 
     public EarlyBinder(
         KeyedStateBackend keyedStateBackend, SerializablePipelineOptions pipelineOptions) {
       this.keyedStateBackend = keyedStateBackend;
-      this.pipelineOptions = pipelineOptions;
+      this.fasterCopy = pipelineOptions.get().as(FlinkPipelineOptions.class).getFasterCopy();
     }
 
     @Override
@@ -1584,7 +1585,7 @@ public <T> ValueState<T> bindValue(String id, StateSpec<ValueState<T>> spec, Cod
       try {
         keyedStateBackend.getOrCreateKeyedState(
             StringSerializer.INSTANCE,
-            new ValueStateDescriptor<>(id, new CoderTypeSerializer<>(coder, pipelineOptions)));
+            new ValueStateDescriptor<>(id, new CoderTypeSerializer<>(coder, fasterCopy)));
       } catch (Exception e) {
         throw new RuntimeException(e);
       }
@@ -1597,7 +1598,7 @@ public <T> BagState<T> bindBag(String id, StateSpec<BagState<T>> spec, Coder<T>
       try {
         keyedStateBackend.getOrCreateKeyedState(
             StringSerializer.INSTANCE,
-            new ListStateDescriptor<>(id, new CoderTypeSerializer<>(elemCoder, pipelineOptions)));
+            new ListStateDescriptor<>(id, new CoderTypeSerializer<>(elemCoder, fasterCopy)));
       } catch (Exception e) {
         throw new RuntimeException(e);
       }
@@ -1612,7 +1613,7 @@ public <T> SetState<T> bindSet(String id, StateSpec<SetState<T>> spec, Coder<T>
             StringSerializer.INSTANCE,
             new MapStateDescriptor<>(
                 id,
-                new CoderTypeSerializer<>(elemCoder, pipelineOptions),
+                new CoderTypeSerializer<>(elemCoder, fasterCopy),
                 BooleanSerializer.INSTANCE));
       } catch (Exception e) {
         throw new RuntimeException(e);
@@ -1631,8 +1632,8 @@ public <KeyT, ValueT> org.apache.beam.sdk.state.MapState<KeyT, ValueT> bindMap(
             StringSerializer.INSTANCE,
             new MapStateDescriptor<>(
                 id,
-                new CoderTypeSerializer<>(mapKeyCoder, pipelineOptions),
-                new CoderTypeSerializer<>(mapValueCoder, pipelineOptions)));
+                new CoderTypeSerializer<>(mapKeyCoder, fasterCopy),
+                new CoderTypeSerializer<>(mapValueCoder, fasterCopy)));
       } catch (Exception e) {
         throw new RuntimeException(e);
       }
@@ -1647,7 +1648,7 @@ public <T> OrderedListState<T> bindOrderedList(
             StringSerializer.INSTANCE,
             new ListStateDescriptor<>(
                 id,
-                new CoderTypeSerializer<>(TimestampedValueCoder.of(elemCoder), pipelineOptions)));
+                new CoderTypeSerializer<>(TimestampedValueCoder.of(elemCoder), fasterCopy)));
       } catch (Exception e) {
         throw new RuntimeException(e);
       }
@@ -1674,7 +1675,7 @@ public <InputT, AccumT, OutputT> CombiningState<InputT, AccumT, OutputT> bindCom
       try {
         keyedStateBackend.getOrCreateKeyedState(
             StringSerializer.INSTANCE,
-            new ValueStateDescriptor<>(id, new CoderTypeSerializer<>(accumCoder, pipelineOptions)));
+            new ValueStateDescriptor<>(id, new CoderTypeSerializer<>(accumCoder, fasterCopy)));
       } catch (Exception e) {
         throw new RuntimeException(e);
       }
@@ -1691,7 +1692,7 @@ CombiningState<InputT, AccumT, OutputT> bindCombiningWithContext(
       try {
         keyedStateBackend.getOrCreateKeyedState(
             StringSerializer.INSTANCE,
-            new ValueStateDescriptor<>(id, new CoderTypeSerializer<>(accumCoder, pipelineOptions)));
+            new ValueStateDescriptor<>(id, new CoderTypeSerializer<>(accumCoder, fasterCopy)));
       } catch (Exception e) {
         throw new RuntimeException(e);
       }
@@ -1707,7 +1708,7 @@ public WatermarkHoldState bindWatermark(
             new MapStateDescriptor<>(
                 "watermark-holds",
                 StringSerializer.INSTANCE,
-                new CoderTypeSerializer<>(InstantCoder.of(), pipelineOptions)));
+                new CoderTypeSerializer<>(InstantCoder.of(), fasterCopy)));
       } catch (Exception e) {
         throw new RuntimeException(e);
       }

From cf670c7772d05623e349a7d23f2af51712cd3f03 Mon Sep 17 00:00:00 2001
From: jto <boudhevil@gmail.com>
Date: Wed, 21 Aug 2024 10:59:17 +0200
Subject: [PATCH 06/26] [Flink] Only serialize states namespace keys if
 necessary

---
 .../wrappers/streaming/DoFnOperator.java      |   4 +-
 .../ExecutableStageDoFnOperator.java          |   7 +-
 .../streaming/state/FlinkStateInternals.java  | 285 ++++++++++++++----
 .../streaming/FlinkStateInternalsTest.java    |   4 +
 4 files changed, 229 insertions(+), 71 deletions(-)

diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/DoFnOperator.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/DoFnOperator.java
index 1072702c3e66..4740bf013781 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/DoFnOperator.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/DoFnOperator.java
@@ -465,7 +465,7 @@ public void initializeState(StateInitializationContext context) throws Exception
     if (keyCoder != null) {
       keyedStateInternals =
           new FlinkStateInternals<>(
-              (KeyedStateBackend) getKeyedStateBackend(), keyCoder, serializedOptions);
+              (KeyedStateBackend) getKeyedStateBackend(), keyCoder, windowingStrategy.getWindowFn().windowCoder(), serializedOptions);
 
       if (timerService == null) {
         timerService =
@@ -595,7 +595,7 @@ private void earlyBindStateIfNeeded() throws IllegalArgumentException, IllegalAc
       if (doFn != null) {
         DoFnSignature signature = DoFnSignatures.getSignature(doFn.getClass());
         FlinkStateInternals.EarlyBinder earlyBinder =
-            new FlinkStateInternals.EarlyBinder(getKeyedStateBackend(), serializedOptions);
+            new FlinkStateInternals.EarlyBinder(getKeyedStateBackend(), serializedOptions, windowingStrategy.getWindowFn().windowCoder());
         for (DoFnSignature.StateDeclaration value : signature.stateDeclarations().values()) {
           StateSpec<?> spec =
               (StateSpec<?>) signature.stateDeclarations().get(value.id()).field().get(doFn);
diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/ExecutableStageDoFnOperator.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/ExecutableStageDoFnOperator.java
index 456f75b0ee67..7ec37cbe6dd3 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/ExecutableStageDoFnOperator.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/ExecutableStageDoFnOperator.java
@@ -247,7 +247,7 @@ protected Lock getLockToAcquireForStateAccessDuringBundles() {
   public void open() throws Exception {
     executableStage = ExecutableStage.fromPayload(payload);
     hasSdfProcessFn = hasSDF(executableStage);
-    initializeUserState(executableStage, getKeyedStateBackend(), pipelineOptions);
+    initializeUserState(executableStage, getKeyedStateBackend(), pipelineOptions, windowCoder);
     // TODO: Wire this into the distributed cache and make it pluggable.
     // TODO: Do we really want this layer of indirection when accessing the stage bundle factory?
     // It's a little strange because this operator is responsible for the lifetime of the stage
@@ -1280,14 +1280,15 @@ void cleanupState(StateInternals stateInternals, Consumer<ByteBuffer> keyContext
   private static void initializeUserState(
       ExecutableStage executableStage,
       @Nullable KeyedStateBackend keyedStateBackend,
-      SerializablePipelineOptions pipelineOptions) {
+      SerializablePipelineOptions pipelineOptions,
+      Coder<? extends BoundedWindow> windowCoder) {
     executableStage
         .getUserStates()
         .forEach(
             ref -> {
               try {
                 keyedStateBackend.getOrCreateKeyedState(
-                    StringSerializer.INSTANCE,
+                    new FlinkStateInternals.FlinkStateNamespaceKeySerializer(windowCoder),
                     new ListStateDescriptor<>(
                         ref.localName(),
                         new CoderTypeSerializer<>(ByteStringCoder.of(), pipelineOptions)));
diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/state/FlinkStateInternals.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/state/FlinkStateInternals.java
index bb662669179d..8102582c4817 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/state/FlinkStateInternals.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/state/FlinkStateInternals.java
@@ -17,6 +17,7 @@
  */
 package org.apache.beam.runners.flink.translation.wrappers.streaming.state;
 
+import java.io.IOException;
 import java.nio.ByteBuffer;
 import java.util.Collections;
 import java.util.HashSet;
@@ -28,6 +29,8 @@
 import java.util.function.Function;
 import java.util.stream.Stream;
 import javax.annotation.Nonnull;
+
+import com.esotericsoftware.kryo.serializers.DefaultSerializers;
 import org.apache.beam.runners.core.StateInternals;
 import org.apache.beam.runners.core.StateNamespace;
 import org.apache.beam.runners.core.StateNamespaces;
@@ -56,6 +59,7 @@
 import org.apache.beam.sdk.state.WatermarkHoldState;
 import org.apache.beam.sdk.transforms.Combine;
 import org.apache.beam.sdk.transforms.CombineWithContext;
+import org.apache.beam.sdk.transforms.windowing.BoundedWindow;
 import org.apache.beam.sdk.transforms.windowing.GlobalWindow;
 import org.apache.beam.sdk.transforms.windowing.TimestampCombiner;
 import org.apache.beam.sdk.util.CombineContextFactory;
@@ -75,8 +79,13 @@
 import org.apache.flink.api.common.state.StateDescriptor;
 import org.apache.flink.api.common.state.ValueStateDescriptor;
 import org.apache.flink.api.common.typeutils.TypeSerializer;
+import org.apache.flink.api.common.typeutils.TypeSerializerSchemaCompatibility;
+import org.apache.flink.api.common.typeutils.TypeSerializerSnapshot;
 import org.apache.flink.api.common.typeutils.base.BooleanSerializer;
 import org.apache.flink.api.common.typeutils.base.StringSerializer;
+import org.apache.flink.core.memory.DataInputView;
+import org.apache.flink.core.memory.DataOutputView;
+import org.apache.flink.runtime.state.JavaSerializer;
 import org.apache.flink.runtime.state.KeyedStateBackend;
 import org.apache.flink.runtime.state.VoidNamespace;
 import org.apache.flink.runtime.state.VoidNamespaceSerializer;
@@ -103,6 +112,7 @@ public class FlinkStateInternals<K> implements StateInternals {
 
   private final KeyedStateBackend<ByteBuffer> flinkStateBackend;
   private final Coder<K> keyCoder;
+  FlinkStateNamespaceKeySerializer namespaceKeySerializer;
 
   private static class StateAndNamespaceDescriptor<T> {
     static <T> StateAndNamespaceDescriptor<T> of(
@@ -168,11 +178,13 @@ public String toString() {
   public FlinkStateInternals(
       KeyedStateBackend<ByteBuffer> flinkStateBackend,
       Coder<K> keyCoder,
+      Coder<? extends BoundedWindow> windowCoder,
       SerializablePipelineOptions pipelineOptions)
       throws Exception {
     this.flinkStateBackend = Objects.requireNonNull(flinkStateBackend);
     this.keyCoder = Objects.requireNonNull(keyCoder);
     this.fasterCopy = pipelineOptions.get().as(FlinkPipelineOptions.class).getFasterCopy();
+    this.namespaceKeySerializer = new FlinkStateNamespaceKeySerializer(windowCoder);
 
     watermarkHoldStateDescriptor =
         new MapStateDescriptor<>(
@@ -242,29 +254,28 @@ private FlinkStateBinder(StateNamespace namespace, StateContext<?> stateContext)
     public <T2> ValueState<T2> bindValue(
         String id, StateSpec<ValueState<T2>> spec, Coder<T2> coder) {
       FlinkValueState<T2> valueState =
-          new FlinkValueState<>(flinkStateBackend, id, namespace, coder, fasterCopy);
+          new FlinkValueState<>(flinkStateBackend, id, namespace, coder, namespaceKeySerializer, fasterCopy);
       collectGlobalWindowStateDescriptor(
           valueState.flinkStateDescriptor,
-          valueState.namespace.stringKey(),
-          StringSerializer.INSTANCE);
+          valueState.namespace, namespaceKeySerializer);
       return valueState;
     }
 
     @Override
     public <T2> BagState<T2> bindBag(String id, StateSpec<BagState<T2>> spec, Coder<T2> elemCoder) {
       FlinkBagState<T2> bagState =
-          new FlinkBagState<>(flinkStateBackend, id, namespace, elemCoder, fasterCopy);
+          new FlinkBagState<>(flinkStateBackend, id, namespace, elemCoder, namespaceKeySerializer, fasterCopy);
       collectGlobalWindowStateDescriptor(
-          bagState.flinkStateDescriptor, bagState.namespace.stringKey(), StringSerializer.INSTANCE);
+          bagState.flinkStateDescriptor, bagState.namespace, namespaceKeySerializer);
       return bagState;
     }
 
     @Override
     public <T2> SetState<T2> bindSet(String id, StateSpec<SetState<T2>> spec, Coder<T2> elemCoder) {
       FlinkSetState<T2> setState =
-          new FlinkSetState<>(flinkStateBackend, id, namespace, elemCoder, fasterCopy);
+          new FlinkSetState<>(flinkStateBackend, id, namespace, elemCoder, namespaceKeySerializer, fasterCopy);
       collectGlobalWindowStateDescriptor(
-          setState.flinkStateDescriptor, setState.namespace.stringKey(), StringSerializer.INSTANCE);
+          setState.flinkStateDescriptor, setState.namespace, namespaceKeySerializer);
       return setState;
     }
 
@@ -276,9 +287,9 @@ public <KeyT, ValueT> MapState<KeyT, ValueT> bindMap(
         Coder<ValueT> mapValueCoder) {
       FlinkMapState<KeyT, ValueT> mapState =
           new FlinkMapState<>(
-              flinkStateBackend, id, namespace, mapKeyCoder, mapValueCoder, fasterCopy);
+              flinkStateBackend, id, namespace, mapKeyCoder, mapValueCoder, namespaceKeySerializer, fasterCopy);
       collectGlobalWindowStateDescriptor(
-          mapState.flinkStateDescriptor, mapState.namespace.stringKey(), StringSerializer.INSTANCE);
+          mapState.flinkStateDescriptor, mapState.namespace, namespaceKeySerializer);
       return mapState;
     }
 
@@ -286,11 +297,11 @@ public <KeyT, ValueT> MapState<KeyT, ValueT> bindMap(
     public <T> OrderedListState<T> bindOrderedList(
         String id, StateSpec<OrderedListState<T>> spec, Coder<T> elemCoder) {
       FlinkOrderedListState<T> flinkOrderedListState =
-          new FlinkOrderedListState<>(flinkStateBackend, id, namespace, elemCoder, fasterCopy);
+          new FlinkOrderedListState<>(flinkStateBackend, id, namespace, elemCoder, namespaceKeySerializer, fasterCopy);
       collectGlobalWindowStateDescriptor(
           flinkOrderedListState.flinkStateDescriptor,
-          flinkOrderedListState.namespace.stringKey(),
-          StringSerializer.INSTANCE);
+          flinkOrderedListState.namespace,
+              namespaceKeySerializer);
       return flinkOrderedListState;
     }
 
@@ -312,11 +323,11 @@ public <InputT, AccumT, OutputT> CombiningState<InputT, AccumT, OutputT> bindCom
         Combine.CombineFn<InputT, AccumT, OutputT> combineFn) {
       FlinkCombiningState<Object, InputT, AccumT, OutputT> combiningState =
           new FlinkCombiningState<>(
-              flinkStateBackend, id, combineFn, namespace, accumCoder, fasterCopy);
+              flinkStateBackend, id, combineFn, namespace, accumCoder, namespaceKeySerializer, fasterCopy);
       collectGlobalWindowStateDescriptor(
           combiningState.flinkStateDescriptor,
-          combiningState.namespace.stringKey(),
-          StringSerializer.INSTANCE);
+          combiningState.namespace,
+              namespaceKeySerializer);
       return combiningState;
     }
 
@@ -334,12 +345,13 @@ CombiningState<InputT, AccumT, OutputT> bindCombiningWithContext(
               combineFn,
               namespace,
               accumCoder,
+              namespaceKeySerializer,
               CombineContextFactory.createFromStateContext(stateContext),
               fasterCopy);
       collectGlobalWindowStateDescriptor(
           combiningStateWithContext.flinkStateDescriptor,
-          combiningStateWithContext.namespace.stringKey(),
-          StringSerializer.INSTANCE);
+          combiningStateWithContext.namespace,
+              namespaceKeySerializer);
       return combiningStateWithContext;
     }
 
@@ -369,23 +381,146 @@ private <T> void collectGlobalWindowStateDescriptor(
     }
   }
 
+  public static class FlinkStateNamespaceKeySerializer extends TypeSerializer<StateNamespace> {
+
+    public Coder<? extends BoundedWindow> getCoder() {
+      return coder;
+    }
+
+    private final Coder<? extends BoundedWindow> coder;
+
+    public FlinkStateNamespaceKeySerializer(Coder<? extends BoundedWindow> coder) {
+      this.coder = coder;
+    }
+    
+    @Override
+    public boolean isImmutableType() {
+      return false;
+    }
+
+    @Override
+    public TypeSerializer<StateNamespace> duplicate() {
+      return this;
+    }
+
+    @Override
+    public StateNamespace createInstance() {
+      return null;
+    }
+
+    @Override
+    public StateNamespace copy(StateNamespace from) {
+      return from;
+    }
+
+    @Override
+    public StateNamespace copy(StateNamespace from, StateNamespace reuse) {
+      return from;
+    }
+
+    @Override
+    public int getLength() {
+      return -1;
+    }
+
+    @Override
+    public void serialize(StateNamespace record, DataOutputView target) throws IOException {
+      StringSerializer.INSTANCE.serialize(record.stringKey(), target);
+    }
+
+    @Override
+    public StateNamespace deserialize(DataInputView source) throws IOException {
+      return StateNamespaces.fromString(StringSerializer.INSTANCE.deserialize(source), coder);
+    }
+
+    @Override
+    public StateNamespace deserialize(StateNamespace reuse, DataInputView source) throws IOException {
+      return deserialize(source);
+    }
+
+    @Override
+    public void copy(DataInputView source, DataOutputView target) throws IOException {
+      throw new UnsupportedOperationException("copy is not supported for FlinkStateNamespace key");
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+      return obj instanceof FlinkStateNamespaceKeySerializer;
+    }
+
+    @Override
+    public int hashCode() {
+      return Objects.hashCode(getClass());
+    }
+
+    @Override
+    public TypeSerializerSnapshot<StateNamespace> snapshotConfiguration() {
+      return new FlinkStateNameSpaceSerializerSnapshot(this);
+    }
+
+    /** Serializer configuration snapshot for compatibility and format evolution. */
+    @SuppressWarnings("WeakerAccess")
+    public final static class FlinkStateNameSpaceSerializerSnapshot implements TypeSerializerSnapshot<StateNamespace> {
+
+      @Nullable
+      private Coder<? extends BoundedWindow> windowCoder;
+
+      public FlinkStateNameSpaceSerializerSnapshot(){
+
+      }
+
+      FlinkStateNameSpaceSerializerSnapshot(FlinkStateNamespaceKeySerializer ser) {
+        this.windowCoder = ser.getCoder();
+      }
+
+      @Override
+      public int getCurrentVersion() {
+        return 0;
+      }
+
+      @Override
+      public void writeSnapshot(DataOutputView out) throws IOException {
+        new JavaSerializer<Coder<? extends BoundedWindow>>().serialize(windowCoder, out);
+      }
+
+      @Override
+      public void readSnapshot(int readVersion, DataInputView in, ClassLoader userCodeClassLoader) throws IOException {
+        this.windowCoder = new JavaSerializer<Coder<? extends BoundedWindow>>().deserialize(in);
+      }
+
+      @Override
+      public TypeSerializer<StateNamespace> restoreSerializer() {
+        return new FlinkStateNamespaceKeySerializer(windowCoder);
+      }
+
+      @Override
+      public TypeSerializerSchemaCompatibility<StateNamespace> resolveSchemaCompatibility(TypeSerializer<StateNamespace> newSerializer) {
+        return TypeSerializerSchemaCompatibility.compatibleAsIs();
+      }
+    }
+  }
+
   private static class FlinkValueState<T> implements ValueState<T> {
 
     private final StateNamespace namespace;
     private final String stateId;
     private final ValueStateDescriptor<T> flinkStateDescriptor;
     private final KeyedStateBackend<ByteBuffer> flinkStateBackend;
+    private final FlinkStateNamespaceKeySerializer namespaceSerializer;
 
     FlinkValueState(
         KeyedStateBackend<ByteBuffer> flinkStateBackend,
         String stateId,
         StateNamespace namespace,
         Coder<T> coder,
+        FlinkStateNamespaceKeySerializer namespaceSerializer,
         boolean fasterCopy) {
 
       this.namespace = namespace;
       this.stateId = stateId;
       this.flinkStateBackend = flinkStateBackend;
+      this.namespaceSerializer = namespaceSerializer;
+
 
       flinkStateDescriptor =
           new ValueStateDescriptor<>(stateId, new CoderTypeSerializer<>(coder, fasterCopy));
@@ -396,7 +531,7 @@ public void write(T input) {
       try {
         flinkStateBackend
             .getPartitionedState(
-                namespace.stringKey(), StringSerializer.INSTANCE, flinkStateDescriptor)
+                namespace, namespaceSerializer, flinkStateDescriptor)
             .update(input);
       } catch (Exception e) {
         throw new RuntimeException("Error updating state.", e);
@@ -413,7 +548,7 @@ public T read() {
       try {
         return flinkStateBackend
             .getPartitionedState(
-                namespace.stringKey(), StringSerializer.INSTANCE, flinkStateDescriptor)
+                namespace, namespaceSerializer, flinkStateDescriptor)
             .value();
       } catch (Exception e) {
         throw new RuntimeException("Error reading state.", e);
@@ -424,8 +559,7 @@ public T read() {
     public void clear() {
       try {
         flinkStateBackend
-            .getPartitionedState(
-                namespace.stringKey(), StringSerializer.INSTANCE, flinkStateDescriptor)
+            .getPartitionedState(namespace, namespaceSerializer, flinkStateDescriptor)
             .clear();
       } catch (Exception e) {
         throw new RuntimeException("Error clearing state.", e);
@@ -458,18 +592,21 @@ private static class FlinkOrderedListState<T> implements OrderedListState<T> {
     private final StateNamespace namespace;
     private final ListStateDescriptor<TimestampedValue<T>> flinkStateDescriptor;
     private final KeyedStateBackend<ByteBuffer> flinkStateBackend;
+    private final FlinkStateNamespaceKeySerializer namespaceSerializer;
 
     FlinkOrderedListState(
         KeyedStateBackend<ByteBuffer> flinkStateBackend,
         String stateId,
         StateNamespace namespace,
         Coder<T> coder,
+        FlinkStateNamespaceKeySerializer namespaceSerializer,
         boolean fasterCopy) {
       this.namespace = namespace;
       this.flinkStateBackend = flinkStateBackend;
       this.flinkStateDescriptor =
           new ListStateDescriptor<>(
               stateId, new CoderTypeSerializer<>(TimestampedValueCoder.of(coder), fasterCopy));
+      this.namespaceSerializer = namespaceSerializer;
     }
 
     @Override
@@ -484,7 +621,7 @@ public void clearRange(Instant minTimestamp, Instant limitTimestamp) {
       try {
         ListState<TimestampedValue<T>> partitionedState =
             flinkStateBackend.getPartitionedState(
-                namespace.stringKey(), StringSerializer.INSTANCE, flinkStateDescriptor);
+                    namespace, namespaceSerializer, flinkStateDescriptor);
         partitionedState.update(Lists.newArrayList(sortedMap.values()));
       } catch (Exception e) {
         throw new RuntimeException("Error adding to bag state.", e);
@@ -501,7 +638,7 @@ public void add(TimestampedValue<T> value) {
       try {
         ListState<TimestampedValue<T>> partitionedState =
             flinkStateBackend.getPartitionedState(
-                namespace.stringKey(), StringSerializer.INSTANCE, flinkStateDescriptor);
+                    namespace, namespaceSerializer, flinkStateDescriptor);
         partitionedState.add(value);
       } catch (Exception e) {
         throw new RuntimeException("Error adding to bag state.", e);
@@ -517,7 +654,7 @@ public Boolean read() {
             Iterable<TimestampedValue<T>> result =
                 flinkStateBackend
                     .getPartitionedState(
-                        namespace.stringKey(), StringSerializer.INSTANCE, flinkStateDescriptor)
+                            namespace, namespaceSerializer, flinkStateDescriptor)
                     .get();
             return result == null;
           } catch (Exception e) {
@@ -543,7 +680,7 @@ private SortedMap<Instant, TimestampedValue<T>> readAsMap() {
       try {
         ListState<TimestampedValue<T>> partitionedState =
             flinkStateBackend.getPartitionedState(
-                namespace.stringKey(), StringSerializer.INSTANCE, flinkStateDescriptor);
+                    namespace, namespaceSerializer, flinkStateDescriptor);
         listValues = MoreObjects.firstNonNull(partitionedState.get(), Collections.emptyList());
       } catch (Exception e) {
         throw new RuntimeException("Error reading state.", e);
@@ -566,7 +703,7 @@ public void clear() {
       try {
         flinkStateBackend
             .getPartitionedState(
-                namespace.stringKey(), StringSerializer.INSTANCE, flinkStateDescriptor)
+                    namespace, namespaceSerializer, flinkStateDescriptor)
             .clear();
       } catch (Exception e) {
         throw new RuntimeException("Error clearing state.", e);
@@ -581,12 +718,14 @@ private static class FlinkBagState<T> implements BagState<T> {
     private final ListStateDescriptor<T> flinkStateDescriptor;
     private final KeyedStateBackend<ByteBuffer> flinkStateBackend;
     private final boolean storesVoidValues;
+    private final FlinkStateNamespaceKeySerializer namespaceSerializer;
 
     FlinkBagState(
         KeyedStateBackend<ByteBuffer> flinkStateBackend,
         String stateId,
         StateNamespace namespace,
         Coder<T> coder,
+        FlinkStateNamespaceKeySerializer namespaceSerializer,
         boolean fasterCopy) {
 
       this.namespace = namespace;
@@ -595,6 +734,7 @@ private static class FlinkBagState<T> implements BagState<T> {
       this.storesVoidValues = coder instanceof VoidCoder;
       this.flinkStateDescriptor =
           new ListStateDescriptor<>(stateId, new CoderTypeSerializer<>(coder, fasterCopy));
+      this.namespaceSerializer = namespaceSerializer;
     }
 
     @Override
@@ -602,7 +742,7 @@ public void add(T input) {
       try {
         ListState<T> partitionedState =
             flinkStateBackend.getPartitionedState(
-                namespace.stringKey(), StringSerializer.INSTANCE, flinkStateDescriptor);
+                    namespace, namespaceSerializer, flinkStateDescriptor);
         if (storesVoidValues) {
           Preconditions.checkState(input == null, "Expected to a null value but was: %s", input);
           // Flink does not allow storing null values
@@ -626,7 +766,7 @@ public Iterable<T> read() {
       try {
         ListState<T> partitionedState =
             flinkStateBackend.getPartitionedState(
-                namespace.stringKey(), StringSerializer.INSTANCE, flinkStateDescriptor);
+                namespace, namespaceSerializer, flinkStateDescriptor);
         Iterable<T> result = partitionedState.get();
         if (storesVoidValues) {
           return () -> {
@@ -663,7 +803,7 @@ public Boolean read() {
             Iterable<T> result =
                 flinkStateBackend
                     .getPartitionedState(
-                        namespace.stringKey(), StringSerializer.INSTANCE, flinkStateDescriptor)
+                        namespace, namespaceSerializer, flinkStateDescriptor)
                     .get();
             return result == null;
           } catch (Exception e) {
@@ -683,7 +823,7 @@ public void clear() {
       try {
         flinkStateBackend
             .getPartitionedState(
-                namespace.stringKey(), StringSerializer.INSTANCE, flinkStateDescriptor)
+                namespace, namespaceSerializer, flinkStateDescriptor)
             .clear();
       } catch (Exception e) {
         throw new RuntimeException("Error clearing state.", e);
@@ -720,6 +860,7 @@ private static class FlinkCombiningState<K, InputT, AccumT, OutputT>
     private final Combine.CombineFn<InputT, AccumT, OutputT> combineFn;
     private final ValueStateDescriptor<AccumT> flinkStateDescriptor;
     private final KeyedStateBackend<ByteBuffer> flinkStateBackend;
+    private final FlinkStateNamespaceKeySerializer namespaceSerializer;
 
     FlinkCombiningState(
         KeyedStateBackend<ByteBuffer> flinkStateBackend,
@@ -727,12 +868,14 @@ private static class FlinkCombiningState<K, InputT, AccumT, OutputT>
         Combine.CombineFn<InputT, AccumT, OutputT> combineFn,
         StateNamespace namespace,
         Coder<AccumT> accumCoder,
+        FlinkStateNamespaceKeySerializer namespaceSerializer,
         boolean fasterCopy) {
 
       this.namespace = namespace;
       this.stateId = stateId;
       this.combineFn = combineFn;
       this.flinkStateBackend = flinkStateBackend;
+      this.namespaceSerializer = namespaceSerializer;
 
       flinkStateDescriptor =
           new ValueStateDescriptor<>(
@@ -749,7 +892,7 @@ public void add(InputT value) {
       try {
         org.apache.flink.api.common.state.ValueState<AccumT> state =
             flinkStateBackend.getPartitionedState(
-                namespace.stringKey(), StringSerializer.INSTANCE, flinkStateDescriptor);
+                namespace, namespaceSerializer, flinkStateDescriptor);
 
         AccumT current = state.value();
         if (current == null) {
@@ -767,7 +910,7 @@ public void addAccum(AccumT accum) {
       try {
         org.apache.flink.api.common.state.ValueState<AccumT> state =
             flinkStateBackend.getPartitionedState(
-                namespace.stringKey(), StringSerializer.INSTANCE, flinkStateDescriptor);
+                namespace, namespaceSerializer, flinkStateDescriptor);
 
         AccumT current = state.value();
         if (current == null) {
@@ -787,7 +930,7 @@ public AccumT getAccum() {
         AccumT accum =
             flinkStateBackend
                 .getPartitionedState(
-                    namespace.stringKey(), StringSerializer.INSTANCE, flinkStateDescriptor)
+                    namespace, namespaceSerializer, flinkStateDescriptor)
                 .value();
         return accum != null ? accum : combineFn.createAccumulator();
       } catch (Exception e) {
@@ -805,7 +948,7 @@ public OutputT read() {
       try {
         org.apache.flink.api.common.state.ValueState<AccumT> state =
             flinkStateBackend.getPartitionedState(
-                namespace.stringKey(), StringSerializer.INSTANCE, flinkStateDescriptor);
+                namespace, namespaceSerializer, flinkStateDescriptor);
 
         AccumT accum = state.value();
         if (accum != null) {
@@ -826,7 +969,7 @@ public Boolean read() {
           try {
             return flinkStateBackend
                     .getPartitionedState(
-                        namespace.stringKey(), StringSerializer.INSTANCE, flinkStateDescriptor)
+                        namespace, namespaceSerializer, flinkStateDescriptor)
                     .value()
                 == null;
           } catch (Exception e) {
@@ -846,7 +989,7 @@ public void clear() {
       try {
         flinkStateBackend
             .getPartitionedState(
-                namespace.stringKey(), StringSerializer.INSTANCE, flinkStateDescriptor)
+                namespace, namespaceSerializer, flinkStateDescriptor)
             .clear();
       } catch (Exception e) {
         throw new RuntimeException("Error clearing state.", e);
@@ -884,6 +1027,7 @@ private static class FlinkCombiningStateWithContext<K, InputT, AccumT, OutputT>
     private final ValueStateDescriptor<AccumT> flinkStateDescriptor;
     private final KeyedStateBackend<ByteBuffer> flinkStateBackend;
     private final CombineWithContext.Context context;
+    private final FlinkStateNamespaceKeySerializer namespaceSerializer;
 
     FlinkCombiningStateWithContext(
         KeyedStateBackend<ByteBuffer> flinkStateBackend,
@@ -891,6 +1035,7 @@ private static class FlinkCombiningStateWithContext<K, InputT, AccumT, OutputT>
         CombineWithContext.CombineFnWithContext<InputT, AccumT, OutputT> combineFn,
         StateNamespace namespace,
         Coder<AccumT> accumCoder,
+        FlinkStateNamespaceKeySerializer namespaceSerializer,
         CombineWithContext.Context context,
         boolean fasterCopy) {
 
@@ -899,6 +1044,7 @@ private static class FlinkCombiningStateWithContext<K, InputT, AccumT, OutputT>
       this.combineFn = combineFn;
       this.flinkStateBackend = flinkStateBackend;
       this.context = context;
+      this.namespaceSerializer = namespaceSerializer;
 
       flinkStateDescriptor =
           new ValueStateDescriptor<>(
@@ -915,7 +1061,7 @@ public void add(InputT value) {
       try {
         org.apache.flink.api.common.state.ValueState<AccumT> state =
             flinkStateBackend.getPartitionedState(
-                namespace.stringKey(), StringSerializer.INSTANCE, flinkStateDescriptor);
+                namespace, namespaceSerializer, flinkStateDescriptor);
 
         AccumT current = state.value();
         if (current == null) {
@@ -933,7 +1079,7 @@ public void addAccum(AccumT accum) {
       try {
         org.apache.flink.api.common.state.ValueState<AccumT> state =
             flinkStateBackend.getPartitionedState(
-                namespace.stringKey(), StringSerializer.INSTANCE, flinkStateDescriptor);
+                namespace, namespaceSerializer, flinkStateDescriptor);
 
         AccumT current = state.value();
         if (current == null) {
@@ -953,7 +1099,7 @@ public AccumT getAccum() {
         AccumT accum =
             flinkStateBackend
                 .getPartitionedState(
-                    namespace.stringKey(), StringSerializer.INSTANCE, flinkStateDescriptor)
+                    namespace, namespaceSerializer, flinkStateDescriptor)
                 .value();
         return accum != null ? accum : combineFn.createAccumulator(context);
       } catch (Exception e) {
@@ -971,7 +1117,7 @@ public OutputT read() {
       try {
         org.apache.flink.api.common.state.ValueState<AccumT> state =
             flinkStateBackend.getPartitionedState(
-                namespace.stringKey(), StringSerializer.INSTANCE, flinkStateDescriptor);
+                namespace, namespaceSerializer, flinkStateDescriptor);
 
         AccumT accum = state.value();
         if (accum != null) {
@@ -992,7 +1138,7 @@ public Boolean read() {
           try {
             return flinkStateBackend
                     .getPartitionedState(
-                        namespace.stringKey(), StringSerializer.INSTANCE, flinkStateDescriptor)
+                        namespace, namespaceSerializer, flinkStateDescriptor)
                     .value()
                 == null;
           } catch (Exception e) {
@@ -1012,7 +1158,7 @@ public void clear() {
       try {
         flinkStateBackend
             .getPartitionedState(
-                namespace.stringKey(), StringSerializer.INSTANCE, flinkStateDescriptor)
+                namespace, namespaceSerializer, flinkStateDescriptor)
             .clear();
       } catch (Exception e) {
         throw new RuntimeException("Error clearing state.", e);
@@ -1172,6 +1318,7 @@ private static class FlinkMapState<KeyT, ValueT> implements MapState<KeyT, Value
     private final String stateId;
     private final MapStateDescriptor<KeyT, ValueT> flinkStateDescriptor;
     private final KeyedStateBackend<ByteBuffer> flinkStateBackend;
+    private final FlinkStateNamespaceKeySerializer namespaceSerializer;
 
     FlinkMapState(
         KeyedStateBackend<ByteBuffer> flinkStateBackend,
@@ -1179,6 +1326,7 @@ private static class FlinkMapState<KeyT, ValueT> implements MapState<KeyT, Value
         StateNamespace namespace,
         Coder<KeyT> mapKeyCoder,
         Coder<ValueT> mapValueCoder,
+        FlinkStateNamespaceKeySerializer namespaceSerializer,
         boolean fasterCopy) {
       this.namespace = namespace;
       this.stateId = stateId;
@@ -1188,6 +1336,7 @@ private static class FlinkMapState<KeyT, ValueT> implements MapState<KeyT, Value
               stateId,
               new CoderTypeSerializer<>(mapKeyCoder, fasterCopy),
               new CoderTypeSerializer<>(mapValueCoder, fasterCopy));
+      this.namespaceSerializer = namespaceSerializer;
     }
 
     @Override
@@ -1205,7 +1354,7 @@ public ReadableState<ValueT> get(final KeyT input) {
             ValueT value =
                 flinkStateBackend
                     .getPartitionedState(
-                        namespace.stringKey(), StringSerializer.INSTANCE, flinkStateDescriptor)
+                        namespace, namespaceSerializer, flinkStateDescriptor)
                     .get(key);
             return (value != null) ? value : defaultValue;
           } catch (Exception e) {
@@ -1225,7 +1374,7 @@ public void put(KeyT key, ValueT value) {
       try {
         flinkStateBackend
             .getPartitionedState(
-                namespace.stringKey(), StringSerializer.INSTANCE, flinkStateDescriptor)
+                namespace, namespaceSerializer, flinkStateDescriptor)
             .put(key, value);
       } catch (Exception e) {
         throw new RuntimeException("Error put kv to state.", e);
@@ -1239,13 +1388,13 @@ public ReadableState<ValueT> computeIfAbsent(
         ValueT current =
             flinkStateBackend
                 .getPartitionedState(
-                    namespace.stringKey(), StringSerializer.INSTANCE, flinkStateDescriptor)
+                    namespace, namespaceSerializer, flinkStateDescriptor)
                 .get(key);
 
         if (current == null) {
           flinkStateBackend
               .getPartitionedState(
-                  namespace.stringKey(), StringSerializer.INSTANCE, flinkStateDescriptor)
+                  namespace, namespaceSerializer, flinkStateDescriptor)
               .put(key, mappingFunction.apply(key));
         }
         return ReadableStates.immediate(current);
@@ -1259,7 +1408,7 @@ public void remove(KeyT key) {
       try {
         flinkStateBackend
             .getPartitionedState(
-                namespace.stringKey(), StringSerializer.INSTANCE, flinkStateDescriptor)
+                namespace, namespaceSerializer, flinkStateDescriptor)
             .remove(key);
       } catch (Exception e) {
         throw new RuntimeException("Error remove map state key.", e);
@@ -1275,7 +1424,7 @@ public Iterable<KeyT> read() {
             Iterable<KeyT> result =
                 flinkStateBackend
                     .getPartitionedState(
-                        namespace.stringKey(), StringSerializer.INSTANCE, flinkStateDescriptor)
+                        namespace, namespaceSerializer, flinkStateDescriptor)
                     .keys();
             return result != null ? ImmutableList.copyOf(result) : Collections.emptyList();
           } catch (Exception e) {
@@ -1299,7 +1448,7 @@ public Iterable<ValueT> read() {
             Iterable<ValueT> result =
                 flinkStateBackend
                     .getPartitionedState(
-                        namespace.stringKey(), StringSerializer.INSTANCE, flinkStateDescriptor)
+                        namespace, namespaceSerializer, flinkStateDescriptor)
                     .values();
             return result != null ? ImmutableList.copyOf(result) : Collections.emptyList();
           } catch (Exception e) {
@@ -1323,7 +1472,7 @@ public Iterable<Map.Entry<KeyT, ValueT>> read() {
             Iterable<Map.Entry<KeyT, ValueT>> result =
                 flinkStateBackend
                     .getPartitionedState(
-                        namespace.stringKey(), StringSerializer.INSTANCE, flinkStateDescriptor)
+                        namespace, namespaceSerializer, flinkStateDescriptor)
                     .entries();
             return result != null ? ImmutableList.copyOf(result) : Collections.emptyList();
           } catch (Exception e) {
@@ -1362,7 +1511,7 @@ public void clear() {
       try {
         flinkStateBackend
             .getPartitionedState(
-                namespace.stringKey(), StringSerializer.INSTANCE, flinkStateDescriptor)
+                namespace, namespaceSerializer, flinkStateDescriptor)
             .clear();
       } catch (Exception e) {
         throw new RuntimeException("Error clearing state.", e);
@@ -1397,12 +1546,14 @@ private static class FlinkSetState<T> implements SetState<T> {
     private final String stateId;
     private final MapStateDescriptor<T, Boolean> flinkStateDescriptor;
     private final KeyedStateBackend<ByteBuffer> flinkStateBackend;
+    private final FlinkStateNamespaceKeySerializer namespaceSerializer;
 
     FlinkSetState(
         KeyedStateBackend<ByteBuffer> flinkStateBackend,
         String stateId,
         StateNamespace namespace,
         Coder<T> coder,
+        FlinkStateNamespaceKeySerializer namespaceSerializer,
         boolean fasterCopy) {
       this.namespace = namespace;
       this.stateId = stateId;
@@ -1420,7 +1571,7 @@ public ReadableState<Boolean> contains(final T t) {
         Boolean result =
             flinkStateBackend
                 .getPartitionedState(
-                    namespace.stringKey(), StringSerializer.INSTANCE, flinkStateDescriptor)
+                    namespace, namespaceSerializer, flinkStateDescriptor)
                 .get(t);
         return ReadableStates.immediate(result != null && result);
       } catch (Exception e) {
@@ -1433,7 +1584,7 @@ public ReadableState<Boolean> addIfAbsent(final T t) {
       try {
         org.apache.flink.api.common.state.MapState<T, Boolean> state =
             flinkStateBackend.getPartitionedState(
-                namespace.stringKey(), StringSerializer.INSTANCE, flinkStateDescriptor);
+                namespace, namespaceSerializer, flinkStateDescriptor);
         boolean alreadyContained = state.contains(t);
         if (!alreadyContained) {
           state.put(t, true);
@@ -1449,7 +1600,7 @@ public void remove(T t) {
       try {
         flinkStateBackend
             .getPartitionedState(
-                namespace.stringKey(), StringSerializer.INSTANCE, flinkStateDescriptor)
+                namespace, namespaceSerializer, flinkStateDescriptor)
             .remove(t);
       } catch (Exception e) {
         throw new RuntimeException("Error remove value to state.", e);
@@ -1466,7 +1617,7 @@ public void add(T value) {
       try {
         flinkStateBackend
             .getPartitionedState(
-                namespace.stringKey(), StringSerializer.INSTANCE, flinkStateDescriptor)
+                namespace, namespaceSerializer, flinkStateDescriptor)
             .put(value, true);
       } catch (Exception e) {
         throw new RuntimeException("Error add value to state.", e);
@@ -1482,7 +1633,7 @@ public Boolean read() {
             Iterable<T> result =
                 flinkStateBackend
                     .getPartitionedState(
-                        namespace.stringKey(), StringSerializer.INSTANCE, flinkStateDescriptor)
+                        namespace, namespaceSerializer, flinkStateDescriptor)
                     .keys();
             return result == null || Iterables.isEmpty(result);
           } catch (Exception e) {
@@ -1503,7 +1654,7 @@ public Iterable<T> read() {
         Iterable<T> result =
             flinkStateBackend
                 .getPartitionedState(
-                    namespace.stringKey(), StringSerializer.INSTANCE, flinkStateDescriptor)
+                    namespace, namespaceSerializer, flinkStateDescriptor)
                 .keys();
         return result != null ? ImmutableList.copyOf(result) : Collections.emptyList();
       } catch (Exception e) {
@@ -1516,7 +1667,7 @@ public void clear() {
       try {
         flinkStateBackend
             .getPartitionedState(
-                namespace.stringKey(), StringSerializer.INSTANCE, flinkStateDescriptor)
+                namespace, namespaceSerializer, flinkStateDescriptor)
             .clear();
       } catch (Exception e) {
         throw new RuntimeException("Error clearing state.", e);
@@ -1573,18 +1724,20 @@ public static class EarlyBinder implements StateBinder {
 
     private final KeyedStateBackend keyedStateBackend;
     private final Boolean fasterCopy;
+    private final FlinkStateNamespaceKeySerializer namespaceSerializer;
 
     public EarlyBinder(
-        KeyedStateBackend keyedStateBackend, SerializablePipelineOptions pipelineOptions) {
+        KeyedStateBackend keyedStateBackend, SerializablePipelineOptions pipelineOptions, Coder<? extends BoundedWindow> windowCoder) {
       this.keyedStateBackend = keyedStateBackend;
       this.fasterCopy = pipelineOptions.get().as(FlinkPipelineOptions.class).getFasterCopy();
+      this.namespaceSerializer = new FlinkStateNamespaceKeySerializer(windowCoder);
     }
 
     @Override
     public <T> ValueState<T> bindValue(String id, StateSpec<ValueState<T>> spec, Coder<T> coder) {
       try {
         keyedStateBackend.getOrCreateKeyedState(
-            StringSerializer.INSTANCE,
+            namespaceSerializer,
             new ValueStateDescriptor<>(id, new CoderTypeSerializer<>(coder, fasterCopy)));
       } catch (Exception e) {
         throw new RuntimeException(e);
@@ -1597,7 +1750,7 @@ public <T> ValueState<T> bindValue(String id, StateSpec<ValueState<T>> spec, Cod
     public <T> BagState<T> bindBag(String id, StateSpec<BagState<T>> spec, Coder<T> elemCoder) {
       try {
         keyedStateBackend.getOrCreateKeyedState(
-            StringSerializer.INSTANCE,
+            namespaceSerializer,
             new ListStateDescriptor<>(id, new CoderTypeSerializer<>(elemCoder, fasterCopy)));
       } catch (Exception e) {
         throw new RuntimeException(e);
@@ -1610,7 +1763,7 @@ public <T> BagState<T> bindBag(String id, StateSpec<BagState<T>> spec, Coder<T>
     public <T> SetState<T> bindSet(String id, StateSpec<SetState<T>> spec, Coder<T> elemCoder) {
       try {
         keyedStateBackend.getOrCreateKeyedState(
-            StringSerializer.INSTANCE,
+            namespaceSerializer,
             new MapStateDescriptor<>(
                 id,
                 new CoderTypeSerializer<>(elemCoder, fasterCopy),
@@ -1629,7 +1782,7 @@ public <KeyT, ValueT> org.apache.beam.sdk.state.MapState<KeyT, ValueT> bindMap(
         Coder<ValueT> mapValueCoder) {
       try {
         keyedStateBackend.getOrCreateKeyedState(
-            StringSerializer.INSTANCE,
+            namespaceSerializer,
             new MapStateDescriptor<>(
                 id,
                 new CoderTypeSerializer<>(mapKeyCoder, fasterCopy),
@@ -1645,7 +1798,7 @@ public <T> OrderedListState<T> bindOrderedList(
         String id, StateSpec<OrderedListState<T>> spec, Coder<T> elemCoder) {
       try {
         keyedStateBackend.getOrCreateKeyedState(
-            StringSerializer.INSTANCE,
+            namespaceSerializer,
             new ListStateDescriptor<>(
                 id,
                 new CoderTypeSerializer<>(TimestampedValueCoder.of(elemCoder), fasterCopy)));
@@ -1674,7 +1827,7 @@ public <InputT, AccumT, OutputT> CombiningState<InputT, AccumT, OutputT> bindCom
         Combine.CombineFn<InputT, AccumT, OutputT> combineFn) {
       try {
         keyedStateBackend.getOrCreateKeyedState(
-            StringSerializer.INSTANCE,
+            namespaceSerializer,
             new ValueStateDescriptor<>(id, new CoderTypeSerializer<>(accumCoder, fasterCopy)));
       } catch (Exception e) {
         throw new RuntimeException(e);
@@ -1691,7 +1844,7 @@ CombiningState<InputT, AccumT, OutputT> bindCombiningWithContext(
             CombineWithContext.CombineFnWithContext<InputT, AccumT, OutputT> combineFn) {
       try {
         keyedStateBackend.getOrCreateKeyedState(
-            StringSerializer.INSTANCE,
+            namespaceSerializer,
             new ValueStateDescriptor<>(id, new CoderTypeSerializer<>(accumCoder, fasterCopy)));
       } catch (Exception e) {
         throw new RuntimeException(e);
diff --git a/runners/flink/src/test/java/org/apache/beam/runners/flink/streaming/FlinkStateInternalsTest.java b/runners/flink/src/test/java/org/apache/beam/runners/flink/streaming/FlinkStateInternalsTest.java
index d0338ec3b0d3..b816e79991ab 100644
--- a/runners/flink/src/test/java/org/apache/beam/runners/flink/streaming/FlinkStateInternalsTest.java
+++ b/runners/flink/src/test/java/org/apache/beam/runners/flink/streaming/FlinkStateInternalsTest.java
@@ -68,6 +68,7 @@ protected StateInternals createStateInternals() {
       return new FlinkStateInternals<>(
           keyedStateBackend,
           StringUtf8Coder.of(),
+          IntervalWindow.getCoder(),
           new SerializablePipelineOptions(FlinkPipelineOptions.defaults()));
     } catch (Exception e) {
       throw new RuntimeException(e);
@@ -81,6 +82,7 @@ public void testWatermarkHoldsPersistence() throws Exception {
         new FlinkStateInternals<>(
             keyedStateBackend,
             StringUtf8Coder.of(),
+            IntervalWindow.getCoder(),
             new SerializablePipelineOptions(FlinkPipelineOptions.defaults()));
 
     StateTag<WatermarkHoldState> stateTag =
@@ -136,6 +138,7 @@ public void testWatermarkHoldsPersistence() throws Exception {
         new FlinkStateInternals<>(
             keyedStateBackend,
             StringUtf8Coder.of(),
+            IntervalWindow.getCoder(),
             new SerializablePipelineOptions(FlinkPipelineOptions.defaults()));
     globalWindow = stateInternals.state(StateNamespaces.global(), stateTag);
     fixedWindow =
@@ -173,6 +176,7 @@ public void testGlobalWindowWatermarkHoldClear() throws Exception {
         new FlinkStateInternals<>(
             keyedStateBackend,
             StringUtf8Coder.of(),
+            IntervalWindow.getCoder(),
             new SerializablePipelineOptions(FlinkPipelineOptions.defaults()));
     StateTag<WatermarkHoldState> stateTag =
         StateTags.watermarkStateInternal("hold", TimestampCombiner.EARLIEST);

From e805ad1addee514eaf422ffe470368d0863fabc6 Mon Sep 17 00:00:00 2001
From: jto <boudhevil@gmail.com>
Date: Tue, 6 Aug 2024 14:53:14 +0200
Subject: [PATCH 07/26] [Flink] Make ToKeyedWorkItem part of the DoFnOperator

---
 ...nkStreamingPortablePipelineTranslator.java |  20 +-
 .../FlinkStreamingTransformTranslators.java   | 155 ++---
 .../wrappers/streaming/DoFnOperator.java      |  52 +-
 .../ExecutableStageDoFnOperator.java          |   3 +-
 .../streaming/SplittableDoFnOperator.java     |   5 +-
 .../streaming/WindowDoFnOperator.java         |  22 +-
 .../flink/FlinkPipelineOptionsTest.java       |   4 +-
 .../wrappers/streaming/DoFnOperatorTest.java  |  54 +-
 .../streaming/WindowDoFnOperatorTest.java     | 620 +++++++++---------
 9 files changed, 456 insertions(+), 479 deletions(-)

diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingPortablePipelineTranslator.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingPortablePipelineTranslator.java
index 836c825300db..e7244bf982d0 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingPortablePipelineTranslator.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingPortablePipelineTranslator.java
@@ -430,24 +430,16 @@ private <K, V> SingleOutputStreamOperator<WindowedValue<KV<K, Iterable<V>>>> add
     WindowedValue.FullWindowedValueCoder<KeyedWorkItem<K, V>> windowedWorkItemCoder =
         WindowedValue.getFullCoder(workItemCoder, windowingStrategy.getWindowFn().windowCoder());
 
-    CoderTypeInformation<WindowedValue<KeyedWorkItem<K, V>>> workItemTypeInfo =
-        new CoderTypeInformation<>(windowedWorkItemCoder, context.getPipelineOptions());
-
-    DataStream<WindowedValue<KeyedWorkItem<K, V>>> workItemStream =
-        inputDataStream
-            .flatMap(
-                new FlinkStreamingTransformTranslators.ToKeyedWorkItem<>(
-                    context.getPipelineOptions()))
-            .returns(workItemTypeInfo)
-            .name("ToKeyedWorkItem");
-
     WorkItemKeySelector<K, V> keySelector =
         new WorkItemKeySelector<>(
             inputElementCoder.getKeyCoder(),
             new SerializablePipelineOptions(context.getPipelineOptions()));
 
-    KeyedStream<WindowedValue<KeyedWorkItem<K, V>>, ByteBuffer> keyedWorkItemStream =
-        workItemStream.keyBy(keySelector);
+    KeyedStream<WindowedValue<KV<K, V>>, ByteBuffer> keyedWorkItemStream =
+        inputDataStream.keyBy(
+            new KvToByteBufferKeySelector(
+                inputElementCoder.getKeyCoder(),
+                new SerializablePipelineOptions(context.getPipelineOptions())));
 
     SystemReduceFn<K, V, Iterable<V>, Iterable<V>, BoundedWindow> reduceFn =
         SystemReduceFn.buffering(inputElementCoder.getValueCoder());
@@ -872,7 +864,7 @@ private <InputT, OutputT> void translateExecutableStage(
             tagsToIds,
             new SerializablePipelineOptions(context.getPipelineOptions()));
 
-    DoFnOperator<InputT, OutputT> doFnOperator =
+    DoFnOperator<InputT, InputT, OutputT> doFnOperator =
         new ExecutableStageDoFnOperator<>(
             transform.getUniqueName(),
             windowedInputCoder,
diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingTransformTranslators.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingTransformTranslators.java
index 2321306da070..f33fd477ea7b 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingTransformTranslators.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingTransformTranslators.java
@@ -30,6 +30,7 @@
 import java.util.List;
 import java.util.Map;
 import org.apache.beam.runners.core.KeyedWorkItem;
+import org.apache.beam.runners.core.KeyedWorkItemCoder;
 import org.apache.beam.runners.core.SplittableParDoViaKeyedWorkItems;
 import org.apache.beam.runners.core.SystemReduceFn;
 import org.apache.beam.runners.core.construction.SerializablePipelineOptions;
@@ -496,7 +497,7 @@ public RawUnionValue map(T o) throws Exception {
   static class ParDoTranslationHelper {
 
     interface DoFnOperatorFactory<InputT, OutputT> {
-      DoFnOperator<InputT, OutputT> createDoFnOperator(
+      DoFnOperator<InputT, InputT, OutputT> createDoFnOperator(
           DoFn<InputT, OutputT> doFn,
           String stepName,
           List<PCollectionView<?>> sideInputs,
@@ -604,7 +605,7 @@ static <InputT, OutputT> void translateParDo(
               context.getPipelineOptions());
 
       if (sideInputs.isEmpty()) {
-        DoFnOperator<InputT, OutputT> doFnOperator =
+        DoFnOperator<InputT, InputT, OutputT> doFnOperator =
             doFnOperatorFactory.createDoFnOperator(
                 doFn,
                 getCurrentTransformName(context),
@@ -631,7 +632,7 @@ static <InputT, OutputT> void translateParDo(
         Tuple2<Map<Integer, PCollectionView<?>>, DataStream<RawUnionValue>> transformedSideInputs =
             transformSideInputs(sideInputs, context);
 
-        DoFnOperator<InputT, OutputT> doFnOperator =
+        DoFnOperator<InputT, InputT, OutputT> doFnOperator =
             doFnOperatorFactory.createDoFnOperator(
                 doFn,
                 getCurrentTransformName(context),
@@ -943,36 +944,37 @@ public void translateNode(
 
       KvCoder<K, InputT> inputKvCoder = (KvCoder<K, InputT>) input.getCoder();
 
-      SingletonKeyedWorkItemCoder<K, byte[]> workItemCoder =
-          SingletonKeyedWorkItemCoder.of(
-              inputKvCoder.getKeyCoder(),
-              ByteArrayCoder.of(),
-              input.getWindowingStrategy().getWindowFn().windowCoder());
-
       DataStream<WindowedValue<KV<K, InputT>>> inputDataStream = context.getInputDataStream(input);
 
-      WindowedValue.FullWindowedValueCoder<KeyedWorkItem<K, byte[]>> windowedWorkItemCoder =
+      WindowedValue.FullWindowedValueCoder<KV<K, byte[]>> windowedBinaryKVCoder =
           WindowedValue.getFullCoder(
-              workItemCoder, input.getWindowingStrategy().getWindowFn().windowCoder());
+              KvCoder.of(inputKvCoder.getKeyCoder(), ByteArrayCoder.of()),
+              input.getWindowingStrategy().getWindowFn().windowCoder());
 
-      CoderTypeInformation<WindowedValue<KeyedWorkItem<K, byte[]>>> workItemTypeInfo =
-          new CoderTypeInformation<>(windowedWorkItemCoder, context.getPipelineOptions());
+      WindowedValue.FullWindowedValueCoder<KeyedWorkItem<K, byte[]>> windowedKeyedWorkItemCoder =
+          WindowedValue.getFullCoder(
+              KeyedWorkItemCoder.of(
+                  inputKvCoder.getKeyCoder(),
+                  ByteArrayCoder.of(),
+                  input.getWindowingStrategy().getWindowFn().windowCoder()),
+              input.getWindowingStrategy().getWindowFn().windowCoder());
 
-      DataStream<WindowedValue<KeyedWorkItem<K, byte[]>>> workItemStream =
+      CoderTypeInformation<WindowedValue<KV<K, byte[]>>> binaryKVTypeInfo =
+          new CoderTypeInformation<>(windowedBinaryKVCoder, context.getPipelineOptions());
+
+      DataStream<WindowedValue<KV<K, byte[]>>> inputBinaryDataStream =
           inputDataStream
-              .flatMap(
-                  new ToBinaryKeyedWorkItem<>(
-                      context.getPipelineOptions(), inputKvCoder.getValueCoder()))
-              .returns(workItemTypeInfo)
-              .name("ToBinaryKeyedWorkItem");
+              .flatMap(new ToBinaryKV<>(context.getPipelineOptions(), inputKvCoder.getValueCoder()))
+              .returns(binaryKVTypeInfo)
+              .name("ToBinaryKV");
 
-      WorkItemKeySelector<K, byte[]> keySelector =
-          new WorkItemKeySelector<>(
+      KvToByteBufferKeySelector<K, byte[]> keySelector =
+          new KvToByteBufferKeySelector<>(
               inputKvCoder.getKeyCoder(),
               new SerializablePipelineOptions(context.getPipelineOptions()));
 
-      KeyedStream<WindowedValue<KeyedWorkItem<K, byte[]>>, ByteBuffer> keyedWorkItemStream =
-          workItemStream.keyBy(keySelector);
+      KeyedStream<WindowedValue<KV<K, byte[]>>, ByteBuffer> keyedWorkItemStream =
+          inputBinaryDataStream.keyBy(keySelector);
 
       SystemReduceFn<K, byte[], Iterable<byte[]>, Iterable<byte[]>, BoundedWindow> reduceFn =
           SystemReduceFn.buffering(ByteArrayCoder.of());
@@ -987,12 +989,17 @@ public void translateNode(
 
       TupleTag<KV<K, Iterable<byte[]>>> mainTag = new TupleTag<>("main output");
 
+      WorkItemKeySelector<K, byte[]> workItemKeySelector =
+          new WorkItemKeySelector<K, byte[]>(
+              inputKvCoder.getKeyCoder(),
+              new SerializablePipelineOptions(context.getPipelineOptions()));
+
       String fullName = getCurrentTransformName(context);
       WindowDoFnOperator<K, byte[], Iterable<byte[]>> doFnOperator =
           new WindowDoFnOperator<>(
               reduceFn,
               fullName,
-              windowedWorkItemCoder,
+              windowedKeyedWorkItemCoder,
               mainTag,
               Collections.emptyList(),
               new DoFnOperator.MultiOutputOutputManagerFactory<>(
@@ -1004,7 +1011,7 @@ public void translateNode(
               Collections.emptyList(), /* side inputs */
               context.getPipelineOptions(),
               inputKvCoder.getKeyCoder(),
-              keySelector);
+              workItemKeySelector);
 
       final SingleOutputStreamOperator<WindowedValue<KV<K, Iterable<InputT>>>> outDataStream =
           keyedWorkItemStream
@@ -1066,21 +1073,16 @@ public void translateNode(
           WindowedValue.getFullCoder(
               workItemCoder, input.getWindowingStrategy().getWindowFn().windowCoder());
 
-      CoderTypeInformation<WindowedValue<KeyedWorkItem<K, InputT>>> workItemTypeInfo =
-          new CoderTypeInformation<>(windowedWorkItemCoder, context.getPipelineOptions());
-
-      DataStream<WindowedValue<KeyedWorkItem<K, InputT>>> workItemStream =
-          inputDataStream
-              .flatMap(new ToKeyedWorkItem<>(context.getPipelineOptions()))
-              .returns(workItemTypeInfo)
-              .name("ToKeyedWorkItem");
-
       WorkItemKeySelector<K, InputT> keySelector =
           new WorkItemKeySelector<>(
               inputKvCoder.getKeyCoder(),
               new SerializablePipelineOptions(context.getPipelineOptions()));
-      KeyedStream<WindowedValue<KeyedWorkItem<K, InputT>>, ByteBuffer> keyedWorkItemStream =
-          workItemStream.keyBy(keySelector);
+
+      KeyedStream<WindowedValue<KV<K, InputT>>, ByteBuffer> keyedStream =
+          inputDataStream.keyBy(
+              new KvToByteBufferKeySelector<>(
+                  inputKvCoder.getKeyCoder(),
+                  new SerializablePipelineOptions(context.getPipelineOptions())));
 
       GlobalCombineFn<? super InputT, ?, OutputT> combineFn = ((Combine.PerKey) transform).getFn();
       SystemReduceFn<K, InputT, ?, OutputT, BoundedWindow> reduceFn =
@@ -1117,7 +1119,8 @@ public void translateNode(
                 keySelector);
 
         SingleOutputStreamOperator<WindowedValue<KV<K, OutputT>>> outDataStream =
-            keyedWorkItemStream.transform(fullName, outputTypeInfo, doFnOperator).uid(fullName);
+            keyedStream.transform(fullName, outputTypeInfo, doFnOperator).uid(fullName);
+
         context.setOutputDataStream(context.getOutput(transform), outDataStream);
       } else {
         Tuple2<Map<Integer, PCollectionView<?>>, DataStream<RawUnionValue>> transformSideInputs =
@@ -1146,28 +1149,26 @@ public void translateNode(
         // allowed to have only one input keyed, normally.
 
         TwoInputTransformation<
-                WindowedValue<KeyedWorkItem<K, InputT>>,
-                RawUnionValue,
-                WindowedValue<KV<K, OutputT>>>
+                WindowedValue<KV<K, InputT>>, RawUnionValue, WindowedValue<KV<K, OutputT>>>
             rawFlinkTransform =
                 new TwoInputTransformation<>(
-                    keyedWorkItemStream.getTransformation(),
+                    keyedStream.getTransformation(),
                     transformSideInputs.f1.broadcast().getTransformation(),
                     transform.getName(),
                     doFnOperator,
                     outputTypeInfo,
-                    keyedWorkItemStream.getParallelism());
+                    keyedStream.getParallelism());
 
-        rawFlinkTransform.setStateKeyType(keyedWorkItemStream.getKeyType());
-        rawFlinkTransform.setStateKeySelectors(keyedWorkItemStream.getKeySelector(), null);
+        rawFlinkTransform.setStateKeyType(keyedStream.getKeyType());
+        rawFlinkTransform.setStateKeySelectors(keyedStream.getKeySelector(), null);
 
         @SuppressWarnings({"unchecked", "rawtypes"})
         SingleOutputStreamOperator<WindowedValue<KV<K, OutputT>>> outDataStream =
             new SingleOutputStreamOperator(
-                keyedWorkItemStream.getExecutionEnvironment(),
+                keyedStream.getExecutionEnvironment(),
                 rawFlinkTransform) {}; // we have to cheat around the ctor being protected
 
-        keyedWorkItemStream.getExecutionEnvironment().addOperator(rawFlinkTransform);
+        keyedStream.getExecutionEnvironment().addOperator(rawFlinkTransform);
 
         context.setOutputDataStream(context.getOutput(transform), outDataStream);
       }
@@ -1332,51 +1333,13 @@ public void flatMap(T t, Collector<T> collector) throws Exception {
     }
   }
 
-  static class ToKeyedWorkItem<K, InputT>
-      extends RichFlatMapFunction<
-          WindowedValue<KV<K, InputT>>, WindowedValue<KeyedWorkItem<K, InputT>>> {
-
-    private final SerializablePipelineOptions options;
-
-    ToKeyedWorkItem(PipelineOptions options) {
-      this.options = new SerializablePipelineOptions(options);
-    }
-
-    @Override
-    public void open(Configuration parameters) {
-      // Initialize FileSystems for any coders which may want to use the FileSystem,
-      // see https://issues.apache.org/jira/browse/BEAM-8303
-      FileSystems.setDefaultPipelineOptions(options.get());
-    }
-
-    @Override
-    public void flatMap(
-        WindowedValue<KV<K, InputT>> inWithMultipleWindows,
-        Collector<WindowedValue<KeyedWorkItem<K, InputT>>> out) {
-
-      // we need to wrap each one work item per window for now
-      // since otherwise the PushbackSideInputRunner will not correctly
-      // determine whether side inputs are ready
-      //
-      // this is tracked as https://github.com/apache/beam/issues/18358
-      for (WindowedValue<KV<K, InputT>> in : inWithMultipleWindows.explodeWindows()) {
-        SingletonKeyedWorkItem<K, InputT> workItem =
-            new SingletonKeyedWorkItem<>(
-                in.getValue().getKey(), in.withValue(in.getValue().getValue()));
-
-        out.collect(in.withValue(workItem));
-      }
-    }
-  }
-
-  static class ToBinaryKeyedWorkItem<K, InputT>
-      extends RichFlatMapFunction<
-          WindowedValue<KV<K, InputT>>, WindowedValue<KeyedWorkItem<K, byte[]>>> {
+  static class ToBinaryKV<K, InputT>
+      extends RichFlatMapFunction<WindowedValue<KV<K, InputT>>, WindowedValue<KV<K, byte[]>>> {
 
     private final SerializablePipelineOptions options;
     private final Coder<InputT> valueCoder;
 
-    ToBinaryKeyedWorkItem(PipelineOptions options, Coder<InputT> valueCoder) {
+    ToBinaryKV(PipelineOptions options, Coder<InputT> valueCoder) {
       this.options = new SerializablePipelineOptions(options);
       this.valueCoder = valueCoder;
     }
@@ -1390,22 +1353,10 @@ public void open(Configuration parameters) {
 
     @Override
     public void flatMap(
-        WindowedValue<KV<K, InputT>> inWithMultipleWindows,
-        Collector<WindowedValue<KeyedWorkItem<K, byte[]>>> out)
+        WindowedValue<KV<K, InputT>> in, Collector<WindowedValue<KV<K, byte[]>>> out)
         throws CoderException {
-
-      // we need to wrap each one work item per window for now
-      // since otherwise the PushbackSideInputRunner will not correctly
-      // determine whether side inputs are ready
-      //
-      // this is tracked as https://github.com/apache/beam/issues/18358
-      for (WindowedValue<KV<K, InputT>> in : inWithMultipleWindows.explodeWindows()) {
-        final byte[] binaryValue =
-            CoderUtils.encodeToByteArray(valueCoder, in.getValue().getValue());
-        final SingletonKeyedWorkItem<K, byte[]> workItem =
-            new SingletonKeyedWorkItem<>(in.getValue().getKey(), in.withValue(binaryValue));
-        out.collect(in.withValue(workItem));
-      }
+      final byte[] binaryValue = CoderUtils.encodeToByteArray(valueCoder, in.getValue().getValue());
+      out.collect(in.withValue(KV.of(in.getValue().getKey(), binaryValue)));
     }
   }
 
diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/DoFnOperator.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/DoFnOperator.java
index 4740bf013781..772673a91da7 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/DoFnOperator.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/DoFnOperator.java
@@ -27,6 +27,7 @@
 import java.nio.ByteBuffer;
 import java.util.ArrayList;
 import java.util.Collection;
+import java.util.Collections;
 import java.util.HashMap;
 import java.util.Iterator;
 import java.util.LinkedHashMap;
@@ -144,9 +145,9 @@
   "keyfor",
   "nullness"
 }) // TODO(https://github.com/apache/beam/issues/20497)
-public class DoFnOperator<InputT, OutputT> extends AbstractStreamOperator<WindowedValue<OutputT>>
-    implements OneInputStreamOperator<WindowedValue<InputT>, WindowedValue<OutputT>>,
-        TwoInputStreamOperator<WindowedValue<InputT>, RawUnionValue, WindowedValue<OutputT>>,
+public class DoFnOperator<PreInputT, InputT, OutputT> extends AbstractStreamOperator<WindowedValue<OutputT>>
+    implements OneInputStreamOperator<WindowedValue<PreInputT>, WindowedValue<OutputT>>,
+        TwoInputStreamOperator<WindowedValue<PreInputT>, RawUnionValue, WindowedValue<OutputT>>,
         Triggerable<ByteBuffer, TimerData> {
 
   private static final Logger LOG = LoggerFactory.getLogger(DoFnOperator.class);
@@ -358,6 +359,11 @@ protected DoFn<InputT, OutputT> getDoFn() {
     return doFn;
   }
 
+  protected Iterable<WindowedValue<InputT>> preProcess(WindowedValue<PreInputT> input) {
+    // Assume Input is PreInputT
+    return Collections.singletonList((WindowedValue<InputT>) input);
+  }
+
   // allow overriding this, for example SplittableDoFnOperator will not create a
   // stateful DoFn runner because ProcessFn, which is used for executing a Splittable DoFn
   // doesn't play by the normal DoFn rules and WindowDoFnOperator uses LateDataDroppingDoFnRunner
@@ -727,30 +733,34 @@ protected final void setBundleFinishedCallback(Runnable callback) {
   }
 
   @Override
-  public final void processElement(StreamRecord<WindowedValue<InputT>> streamRecord) {
-    checkInvokeStartBundle();
-    LOG.trace("Processing element {} in {}", streamRecord.getValue().getValue(), doFn.getClass());
-    long oldHold = keyCoder != null ? keyedStateInternals.minWatermarkHoldMs() : -1L;
-    doFnRunner.processElement(streamRecord.getValue());
-    checkInvokeFinishBundleByCount();
-    emitWatermarkIfHoldChanged(oldHold);
+  public final void processElement(StreamRecord<WindowedValue<PreInputT>> streamRecord) {
+    for (WindowedValue<InputT> e : preProcess(streamRecord.getValue())) {
+      checkInvokeStartBundle();
+      LOG.trace("Processing element {} in {}", streamRecord.getValue().getValue(), doFn.getClass());
+      long oldHold = keyCoder != null ? keyedStateInternals.minWatermarkHoldMs() : -1L;
+      doFnRunner.processElement(e);
+      checkInvokeFinishBundleByCount();
+      emitWatermarkIfHoldChanged(oldHold);
+    }
   }
 
   @Override
-  public final void processElement1(StreamRecord<WindowedValue<InputT>> streamRecord)
+  public final void processElement1(StreamRecord<WindowedValue<PreInputT>> streamRecord)
       throws Exception {
-    checkInvokeStartBundle();
-    Iterable<WindowedValue<InputT>> justPushedBack =
-        pushbackDoFnRunner.processElementInReadyWindows(streamRecord.getValue());
+    for (WindowedValue<InputT> e : preProcess(streamRecord.getValue())) {
+      checkInvokeStartBundle();
+      Iterable<WindowedValue<InputT>> justPushedBack =
+          pushbackDoFnRunner.processElementInReadyWindows(e);
 
-    long min = pushedBackWatermark;
-    for (WindowedValue<InputT> pushedBackValue : justPushedBack) {
-      min = Math.min(min, pushedBackValue.getTimestamp().getMillis());
-      pushedBackElementsHandler.pushBack(pushedBackValue);
-    }
-    pushedBackWatermark = min;
+      long min = pushedBackWatermark;
+      for (WindowedValue<InputT> pushedBackValue : justPushedBack) {
+        min = Math.min(min, pushedBackValue.getTimestamp().getMillis());
+        pushedBackElementsHandler.pushBack(pushedBackValue);
+      }
+      pushedBackWatermark = min;
 
-    checkInvokeFinishBundleByCount();
+      checkInvokeFinishBundleByCount();
+    }
   }
 
   /**
diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/ExecutableStageDoFnOperator.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/ExecutableStageDoFnOperator.java
index 7ec37cbe6dd3..446a4541dd1a 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/ExecutableStageDoFnOperator.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/ExecutableStageDoFnOperator.java
@@ -138,7 +138,8 @@
   "rawtypes", // TODO(https://github.com/apache/beam/issues/20447)
   "nullness" // TODO(https://github.com/apache/beam/issues/20497)
 })
-public class ExecutableStageDoFnOperator<InputT, OutputT> extends DoFnOperator<InputT, OutputT> {
+public class ExecutableStageDoFnOperator<InputT, OutputT>
+    extends DoFnOperator<InputT, InputT, OutputT> {
 
   private static final Logger LOG = LoggerFactory.getLogger(ExecutableStageDoFnOperator.class);
 
diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/SplittableDoFnOperator.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/SplittableDoFnOperator.java
index 8eae5be177a5..d80dd60a5925 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/SplittableDoFnOperator.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/SplittableDoFnOperator.java
@@ -65,7 +65,10 @@
   "nullness" // TODO(https://github.com/apache/beam/issues/20497)
 })
 public class SplittableDoFnOperator<InputT, OutputT, RestrictionT>
-    extends DoFnOperator<KeyedWorkItem<byte[], KV<InputT, RestrictionT>>, OutputT> {
+    extends DoFnOperator<
+        KeyedWorkItem<byte[], KV<InputT, RestrictionT>>,
+        KeyedWorkItem<byte[], KV<InputT, RestrictionT>>,
+        OutputT> {
 
   private static final Logger LOG = LoggerFactory.getLogger(SplittableDoFnOperator.class);
 
diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/WindowDoFnOperator.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/WindowDoFnOperator.java
index d8f4885ea057..60b20f375f22 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/WindowDoFnOperator.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/WindowDoFnOperator.java
@@ -19,6 +19,7 @@
 
 import static org.apache.beam.runners.core.TimerInternals.TimerData;
 
+import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
@@ -50,7 +51,7 @@
   "nullness" // TODO(https://github.com/apache/beam/issues/20497)
 })
 public class WindowDoFnOperator<K, InputT, OutputT>
-    extends DoFnOperator<KeyedWorkItem<K, InputT>, KV<K, OutputT>> {
+    extends DoFnOperator<KV<K, InputT>, KeyedWorkItem<K, InputT>, KV<K, OutputT>> {
 
   private final SystemReduceFn<K, InputT, ?, OutputT, BoundedWindow> systemReduceFn;
 
@@ -87,6 +88,25 @@ public WindowDoFnOperator(
     this.systemReduceFn = systemReduceFn;
   }
 
+  @Override
+  protected Iterable<WindowedValue<KeyedWorkItem<K, InputT>>> preProcess(
+      WindowedValue<KV<K, InputT>> inWithMultipleWindows) {
+    // we need to wrap each one work item per window for now
+    // since otherwise the PushbackSideInputRunner will not correctly
+    // determine whether side inputs are ready
+    //
+    // this is tracked as https://github.com/apache/beam/issues/18358
+    ArrayList<WindowedValue<KeyedWorkItem<K, InputT>>> inputs = new ArrayList<>();
+    for (WindowedValue<KV<K, InputT>> in : inWithMultipleWindows.explodeWindows()) {
+      SingletonKeyedWorkItem<K, InputT> workItem =
+          new SingletonKeyedWorkItem<>(
+              in.getValue().getKey(), in.withValue(in.getValue().getValue()));
+
+      inputs.add(in.withValue(workItem));
+    }
+    return inputs;
+  }
+
   @Override
   protected DoFnRunner<KeyedWorkItem<K, InputT>, KV<K, OutputT>> createWrappingDoFnRunner(
       DoFnRunner<KeyedWorkItem<K, InputT>, KV<K, OutputT>> wrappedRunner, StepContext stepContext) {
diff --git a/runners/flink/src/test/java/org/apache/beam/runners/flink/FlinkPipelineOptionsTest.java b/runners/flink/src/test/java/org/apache/beam/runners/flink/FlinkPipelineOptionsTest.java
index c20bd077c3f2..9fa7aaca1b69 100644
--- a/runners/flink/src/test/java/org/apache/beam/runners/flink/FlinkPipelineOptionsTest.java
+++ b/runners/flink/src/test/java/org/apache/beam/runners/flink/FlinkPipelineOptionsTest.java
@@ -139,7 +139,7 @@ public void parDoBaseClassPipelineOptionsSerializationTest() throws Exception {
     TupleTag<String> mainTag = new TupleTag<>("main-output");
 
     Coder<WindowedValue<String>> coder = WindowedValue.getValueOnlyCoder(StringUtf8Coder.of());
-    DoFnOperator<String, String> doFnOperator =
+    DoFnOperator<String, String, String> doFnOperator =
         new DoFnOperator<>(
             new TestDoFn(),
             "stepName",
@@ -161,7 +161,7 @@ mainTag, coder, new SerializablePipelineOptions(FlinkPipelineOptions.defaults())
     final byte[] serialized = SerializationUtils.serialize(doFnOperator);
 
     @SuppressWarnings("unchecked")
-    DoFnOperator<Object, Object> deserialized = SerializationUtils.deserialize(serialized);
+    DoFnOperator<Object, Object, Object> deserialized = SerializationUtils.deserialize(serialized);
 
     TypeInformation<WindowedValue<Object>> typeInformation =
         TypeInformation.of(new TypeHint<WindowedValue<Object>>() {});
diff --git a/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/DoFnOperatorTest.java b/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/DoFnOperatorTest.java
index 17cc16cc76e0..124fae05b03e 100644
--- a/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/DoFnOperatorTest.java
+++ b/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/DoFnOperatorTest.java
@@ -149,7 +149,7 @@ public void testSingleOutput() throws Exception {
 
     TupleTag<String> outputTag = new TupleTag<>("main-output");
 
-    DoFnOperator<String, String> doFnOperator =
+    DoFnOperator<String, String, String> doFnOperator =
         new DoFnOperator<>(
             new IdentityDoFn<>(),
             "stepName",
@@ -211,7 +211,7 @@ public void testMultiOutputOutput() throws Exception {
             .put(additionalOutput2, 2)
             .build();
 
-    DoFnOperator<String, String> doFnOperator =
+    DoFnOperator<String, String, String> doFnOperator =
         new DoFnOperator<>(
             new MultiOutputDoFn(additionalOutput1, additionalOutput2),
             "stepName",
@@ -353,7 +353,7 @@ public void onProcessingTime(OnTimerContext context) {
 
     TupleTag<String> outputTag = new TupleTag<>("main-output");
 
-    DoFnOperator<Integer, String> doFnOperator =
+    DoFnOperator<Integer, Integer, String> doFnOperator =
         new DoFnOperator<>(
             fn,
             "stepName",
@@ -441,8 +441,8 @@ public void testWatermarkUpdateAfterWatermarkHoldRelease() throws Exception {
     KeySelector<WindowedValue<KV<String, String>>, ByteBuffer> keySelector =
         e -> FlinkKeyUtils.encodeKey(e.getValue().getKey(), StringUtf8Coder.of());
 
-    DoFnOperator<KV<String, String>, KV<String, String>> doFnOperator =
-        new DoFnOperator<KV<String, String>, KV<String, String>>(
+    DoFnOperator<KV<String, String>, KV<String, String>, KV<String, String>> doFnOperator =
+        new DoFnOperator<KV<String, String>, KV<String, String>, KV<String, String>>(
             new IdentityDoFn<>(),
             "stepName",
             coder,
@@ -616,7 +616,7 @@ public void processElement(ProcessContext context) {
 
     TupleTag<String> outputTag = new TupleTag<>("main-output");
 
-    DoFnOperator<Integer, String> doFnOperator =
+    DoFnOperator<Integer, Integer, String> doFnOperator =
         new DoFnOperator<>(
             fn,
             "stepName",
@@ -866,7 +866,7 @@ public void onTimer(OnTimerContext context, @StateId(stateId) ValueState<String>
     KeySelector<WindowedValue<KV<String, Integer>>, ByteBuffer> keySelector =
         e -> FlinkKeyUtils.encodeKey(e.getValue().getKey(), StringUtf8Coder.of());
 
-    DoFnOperator<KV<String, Integer>, KV<String, Integer>> doFnOperator =
+    DoFnOperator<KV<String, Integer>, KV<String, Integer>, KV<String, Integer>> doFnOperator =
         new DoFnOperator<>(
             fn,
             "stepName",
@@ -917,7 +917,7 @@ void testSideInputs(boolean keyed) throws Exception {
       keySelector = value -> FlinkKeyUtils.encodeKey(value.getValue(), keyCoder);
     }
 
-    DoFnOperator<String, String> doFnOperator =
+    DoFnOperator<String, String, String> doFnOperator =
         new DoFnOperator<>(
             new IdentityDoFn<>(),
             "stepName",
@@ -1115,7 +1115,7 @@ public void nonKeyedParDoSideInputCheckpointing() throws Exception {
                   .put(2, view2)
                   .build();
 
-          DoFnOperator<String, String> doFnOperator =
+          DoFnOperator<String, String, String> doFnOperator =
               new DoFnOperator<>(
                   new IdentityDoFn<>(),
                   "stepName",
@@ -1158,7 +1158,7 @@ public void keyedParDoSideInputCheckpointing() throws Exception {
                   .put(2, view2)
                   .build();
 
-          DoFnOperator<String, String> doFnOperator =
+          DoFnOperator<String, String, String> doFnOperator =
               new DoFnOperator<>(
                   new IdentityDoFn<>(),
                   "stepName",
@@ -1261,7 +1261,7 @@ public void nonKeyedParDoPushbackDataCheckpointing() throws Exception {
                   .put(2, view2)
                   .build();
 
-          DoFnOperator<String, String> doFnOperator =
+          DoFnOperator<String, String, String> doFnOperator =
               new DoFnOperator<>(
                   new IdentityDoFn<>(),
                   "stepName",
@@ -1305,7 +1305,7 @@ public void keyedParDoPushbackDataCheckpointing() throws Exception {
                   .put(2, view2)
                   .build();
 
-          DoFnOperator<String, String> doFnOperator =
+          DoFnOperator<String, String, String> doFnOperator =
               new DoFnOperator<>(
                   new IdentityDoFn<>(),
                   "stepName",
@@ -1504,7 +1504,7 @@ OneInputStreamOperatorTestHarness<WindowedValue<InT>, WindowedValue<OutT>> creat
           TypeInformation<K> keyCoderInfo,
           KeySelector<WindowedValue<InT>, K> keySelector)
           throws Exception {
-    DoFnOperator<InT, OutT> doFnOperator =
+    DoFnOperator<InT, InT, OutT> doFnOperator =
         new DoFnOperator<>(
             fn,
             "stepName",
@@ -1554,7 +1554,7 @@ public void finishBundle(FinishBundleContext context) {
             WindowedValue.getFullCoder(StringUtf8Coder.of(), GlobalWindow.Coder.INSTANCE),
             new SerializablePipelineOptions(options));
 
-    DoFnOperator<String, String> doFnOperator =
+    DoFnOperator<String, String, String> doFnOperator =
         new DoFnOperator<>(
             doFn,
             "stepName",
@@ -1603,7 +1603,7 @@ public void finishBundle(FinishBundleContext context) {
 
     testHarness.close();
 
-    DoFnOperator<String, String> newDoFnOperator =
+    DoFnOperator<String, String, String> newDoFnOperator =
         new DoFnOperator<>(
             doFn,
             "stepName",
@@ -1702,7 +1702,7 @@ public void finishBundle(FinishBundleContext context) {
             WindowedValue.getFullCoder(kvCoder.getValueCoder(), GlobalWindow.Coder.INSTANCE),
             new SerializablePipelineOptions(options));
 
-    DoFnOperator<KV<String, String>, String> doFnOperator =
+    DoFnOperator<KV<String, String>, KV<String, String>, String> doFnOperator =
         new DoFnOperator<>(
             doFn,
             "stepName",
@@ -1819,7 +1819,7 @@ public void testCheckpointBufferingWithMultipleBundles() throws Exception {
             WindowedValue.getFullCoder(StringUtf8Coder.of(), GlobalWindow.Coder.INSTANCE),
             new SerializablePipelineOptions(options));
 
-    Supplier<DoFnOperator<String, String>> doFnOperatorSupplier =
+    Supplier<DoFnOperator<String, String, String>> doFnOperatorSupplier =
         () ->
             new DoFnOperator<>(
                 new IdentityDoFn<>(),
@@ -1838,7 +1838,7 @@ public void testCheckpointBufferingWithMultipleBundles() throws Exception {
                 DoFnSchemaInformation.create(),
                 Collections.emptyMap());
 
-    DoFnOperator<String, String> doFnOperator = doFnOperatorSupplier.get();
+    DoFnOperator<String, String, String> doFnOperator = doFnOperatorSupplier.get();
     OneInputStreamOperatorTestHarness<WindowedValue<String>, WindowedValue<String>> testHarness =
         new OneInputStreamOperatorTestHarness<>(doFnOperator);
 
@@ -1943,7 +1943,7 @@ public void finishBundle(FinishBundleContext context) {
             WindowedValue.getFullCoder(StringUtf8Coder.of(), GlobalWindow.Coder.INSTANCE),
             new SerializablePipelineOptions(options));
 
-    Supplier<DoFnOperator<String, String>> doFnOperatorSupplier =
+    Supplier<DoFnOperator<String, String, String>> doFnOperatorSupplier =
         () ->
             new DoFnOperator<>(
                 doFn,
@@ -1962,7 +1962,7 @@ public void finishBundle(FinishBundleContext context) {
                 DoFnSchemaInformation.create(),
                 Collections.emptyMap());
 
-    DoFnOperator<String, String> doFnOperator = doFnOperatorSupplier.get();
+    DoFnOperator<String, String, String> doFnOperator = doFnOperatorSupplier.get();
     OneInputStreamOperatorTestHarness<WindowedValue<String>, WindowedValue<String>> testHarness =
         new OneInputStreamOperatorTestHarness<>(doFnOperator);
 
@@ -2054,7 +2054,7 @@ public void finishBundle(FinishBundleContext context) {
             WindowedValue.getFullCoder(StringUtf8Coder.of(), GlobalWindow.Coder.INSTANCE),
             new SerializablePipelineOptions(options));
 
-    Supplier<DoFnOperator<String, String>> doFnOperatorSupplier =
+    Supplier<DoFnOperator<String, String, String>> doFnOperatorSupplier =
         () ->
             new DoFnOperator<>(
                 doFn,
@@ -2073,7 +2073,7 @@ public void finishBundle(FinishBundleContext context) {
                 DoFnSchemaInformation.create(),
                 Collections.emptyMap());
 
-    DoFnOperator<String, String> doFnOperator = doFnOperatorSupplier.get();
+    DoFnOperator<String, String, String> doFnOperator = doFnOperatorSupplier.get();
     OneInputStreamOperatorTestHarness<WindowedValue<String>, WindowedValue<String>> testHarness =
         new OneInputStreamOperatorTestHarness<>(doFnOperator);
 
@@ -2151,7 +2151,7 @@ public void finishBundle(FinishBundleContext context) {
             WindowedValue.getFullCoder(kvCoder, GlobalWindow.Coder.INSTANCE),
             new SerializablePipelineOptions(options));
 
-    Supplier<DoFnOperator<KV<String, String>, KV<String, String>>> doFnOperatorSupplier =
+    Supplier<DoFnOperator<KV<String, String>, KV<String, String>, KV<String, String>>> doFnOperatorSupplier =
         () ->
             new DoFnOperator<>(
                 doFn,
@@ -2170,7 +2170,7 @@ public void finishBundle(FinishBundleContext context) {
                 DoFnSchemaInformation.create(),
                 Collections.emptyMap());
 
-    DoFnOperator<KV<String, String>, KV<String, String>> doFnOperator = doFnOperatorSupplier.get();
+    DoFnOperator<KV<String, String>, KV<String, String>, KV<String, String>> doFnOperator = doFnOperatorSupplier.get();
     OneInputStreamOperatorTestHarness<
             WindowedValue<KV<String, String>>, WindowedValue<KV<String, String>>>
         testHarness =
@@ -2307,7 +2307,7 @@ public void testBundleProcessingExceptionIsFatalDuringCheckpointing() throws Exc
             WindowedValue.getFullCoder(StringUtf8Coder.of(), GlobalWindow.Coder.INSTANCE),
             new SerializablePipelineOptions(options));
 
-    DoFnOperator<String, String> doFnOperator =
+    DoFnOperator<String, String, String> doFnOperator =
         new DoFnOperator<>(
             new IdentityDoFn<String>() {
               @FinishBundle
@@ -2346,7 +2346,7 @@ public void finishBundle() {
 
   @Test
   public void testAccumulatorRegistrationOnOperatorClose() throws Exception {
-    DoFnOperator<String, String> doFnOperator = getOperatorForCleanupInspection();
+    DoFnOperator<String, String, String> doFnOperator = getOperatorForCleanupInspection();
     OneInputStreamOperatorTestHarness<WindowedValue<String>, WindowedValue<String>> testHarness =
         new OneInputStreamOperatorTestHarness<>(doFnOperator);
 
@@ -2382,7 +2382,7 @@ public void testRemoveCachedClassReferences() throws Exception {
     assertThat(typeCache.size(), is(0));
   }
 
-  private static DoFnOperator<String, String> getOperatorForCleanupInspection() {
+  private static DoFnOperator<String, String, String> getOperatorForCleanupInspection() {
     FlinkPipelineOptions options = FlinkPipelineOptions.defaults();
     options.setParallelism(4);
 
diff --git a/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/WindowDoFnOperatorTest.java b/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/WindowDoFnOperatorTest.java
index 8fab1bc6c167..fa00b942bad2 100644
--- a/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/WindowDoFnOperatorTest.java
+++ b/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/WindowDoFnOperatorTest.java
@@ -1,310 +1,310 @@
-/*
- * Licensed to the Apache Software Foundation (ASF) under one
- * or more contributor license agreements.  See the NOTICE file
- * distributed with this work for additional information
- * regarding copyright ownership.  The ASF licenses this file
- * to you under the Apache License, Version 2.0 (the
- * "License"); you may not use this file except in compliance
- * with the License.  You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-package org.apache.beam.runners.flink.translation.wrappers.streaming;
-
-import static java.util.Collections.emptyList;
-import static java.util.Collections.emptyMap;
-import static org.apache.beam.runners.flink.translation.wrappers.streaming.StreamRecordStripper.stripStreamRecordFromWindowedValue;
-import static org.apache.beam.sdk.transforms.windowing.PaneInfo.NO_FIRING;
-import static org.apache.beam.sdk.transforms.windowing.PaneInfo.Timing.ON_TIME;
-import static org.hamcrest.MatcherAssert.assertThat;
-import static org.hamcrest.Matchers.containsInAnyOrder;
-import static org.hamcrest.core.Is.is;
-import static org.joda.time.Duration.standardMinutes;
-import static org.junit.Assert.assertEquals;
-
-import java.io.ByteArrayOutputStream;
-import java.nio.ByteBuffer;
-import org.apache.beam.runners.core.KeyedWorkItem;
-import org.apache.beam.runners.core.SystemReduceFn;
-import org.apache.beam.runners.core.construction.SerializablePipelineOptions;
-import org.apache.beam.runners.flink.FlinkPipelineOptions;
-import org.apache.beam.runners.flink.translation.wrappers.streaming.DoFnOperator.MultiOutputOutputManagerFactory;
-import org.apache.beam.sdk.coders.Coder;
-import org.apache.beam.sdk.coders.CoderRegistry;
-import org.apache.beam.sdk.coders.KvCoder;
-import org.apache.beam.sdk.coders.VarLongCoder;
-import org.apache.beam.sdk.transforms.Sum;
-import org.apache.beam.sdk.transforms.windowing.BoundedWindow;
-import org.apache.beam.sdk.transforms.windowing.FixedWindows;
-import org.apache.beam.sdk.transforms.windowing.IntervalWindow;
-import org.apache.beam.sdk.transforms.windowing.PaneInfo;
-import org.apache.beam.sdk.util.AppliedCombineFn;
-import org.apache.beam.sdk.util.WindowedValue;
-import org.apache.beam.sdk.util.WindowedValue.FullWindowedValueCoder;
-import org.apache.beam.sdk.values.KV;
-import org.apache.beam.sdk.values.TupleTag;
-import org.apache.beam.sdk.values.WindowingStrategy;
-import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.Iterables;
-import org.apache.flink.api.java.functions.KeySelector;
-import org.apache.flink.api.java.typeutils.GenericTypeInfo;
-import org.apache.flink.runtime.checkpoint.OperatorSubtaskState;
-import org.apache.flink.streaming.runtime.streamrecord.StreamRecord;
-import org.apache.flink.streaming.util.KeyedOneInputStreamOperatorTestHarness;
-import org.joda.time.Duration;
-import org.joda.time.Instant;
-import org.junit.Test;
-import org.junit.runner.RunWith;
-import org.junit.runners.JUnit4;
-
-/** Tests for {@link WindowDoFnOperator}. */
-@RunWith(JUnit4.class)
-@SuppressWarnings({
-  "rawtypes", // TODO(https://github.com/apache/beam/issues/20447)
-})
-public class WindowDoFnOperatorTest {
-
-  @Test
-  public void testRestore() throws Exception {
-    // test harness
-    KeyedOneInputStreamOperatorTestHarness<
-            ByteBuffer, WindowedValue<KeyedWorkItem<Long, Long>>, WindowedValue<KV<Long, Long>>>
-        testHarness = createTestHarness(getWindowDoFnOperator());
-    testHarness.open();
-
-    // process elements
-    IntervalWindow window = new IntervalWindow(new Instant(0), Duration.millis(10_000));
-    testHarness.processWatermark(0L);
-    testHarness.processElement(
-        Item.builder().key(1L).timestamp(1L).value(100L).window(window).build().toStreamRecord());
-    testHarness.processElement(
-        Item.builder().key(1L).timestamp(2L).value(20L).window(window).build().toStreamRecord());
-    testHarness.processElement(
-        Item.builder().key(2L).timestamp(3L).value(77L).window(window).build().toStreamRecord());
-
-    // create snapshot
-    OperatorSubtaskState snapshot = testHarness.snapshot(0, 0);
-    testHarness.close();
-
-    // restore from the snapshot
-    testHarness = createTestHarness(getWindowDoFnOperator());
-    testHarness.initializeState(snapshot);
-    testHarness.open();
-
-    // close window
-    testHarness.processWatermark(10_000L);
-
-    Iterable<WindowedValue<KV<Long, Long>>> output =
-        stripStreamRecordFromWindowedValue(testHarness.getOutput());
-
-    assertEquals(2, Iterables.size(output));
-    assertThat(
-        output,
-        containsInAnyOrder(
-            WindowedValue.of(
-                KV.of(1L, 120L),
-                new Instant(9_999),
-                window,
-                PaneInfo.createPane(true, true, ON_TIME)),
-            WindowedValue.of(
-                KV.of(2L, 77L),
-                new Instant(9_999),
-                window,
-                PaneInfo.createPane(true, true, ON_TIME))));
-    // cleanup
-    testHarness.close();
-  }
-
-  @Test
-  public void testTimerCleanupOfPendingTimerList() throws Exception {
-    // test harness
-    WindowDoFnOperator<Long, Long, Long> windowDoFnOperator = getWindowDoFnOperator();
-    KeyedOneInputStreamOperatorTestHarness<
-            ByteBuffer, WindowedValue<KeyedWorkItem<Long, Long>>, WindowedValue<KV<Long, Long>>>
-        testHarness = createTestHarness(windowDoFnOperator);
-    testHarness.open();
-
-    DoFnOperator<KeyedWorkItem<Long, Long>, KV<Long, Long>>.FlinkTimerInternals timerInternals =
-        windowDoFnOperator.timerInternals;
-
-    // process elements
-    IntervalWindow window = new IntervalWindow(new Instant(0), Duration.millis(100));
-    IntervalWindow window2 = new IntervalWindow(new Instant(100), Duration.millis(100));
-    testHarness.processWatermark(0L);
-
-    // Use two different keys to check for correct watermark hold calculation
-    testHarness.processElement(
-        Item.builder().key(1L).timestamp(1L).value(100L).window(window).build().toStreamRecord());
-    testHarness.processElement(
-        Item.builder()
-            .key(2L)
-            .timestamp(150L)
-            .value(150L)
-            .window(window2)
-            .build()
-            .toStreamRecord());
-
-    testHarness.processWatermark(1);
-
-    // Note that the following is 1 because the state is key-partitioned
-    assertThat(Iterables.size(timerInternals.pendingTimersById.keys()), is(1));
-
-    assertThat(testHarness.numKeyedStateEntries(), is(6));
-    // close bundle
-    testHarness.setProcessingTime(
-        testHarness.getProcessingTime()
-            + 2 * FlinkPipelineOptions.defaults().getMaxBundleTimeMills());
-    assertThat(windowDoFnOperator.getCurrentOutputWatermark(), is(1L));
-
-    // close window
-    testHarness.processWatermark(100L);
-
-    // Note that the following is zero because we only the first key is active
-    assertThat(Iterables.size(timerInternals.pendingTimersById.keys()), is(0));
-
-    assertThat(testHarness.numKeyedStateEntries(), is(3));
-
-    // close bundle
-    testHarness.setProcessingTime(
-        testHarness.getProcessingTime()
-            + 2 * FlinkPipelineOptions.defaults().getMaxBundleTimeMills());
-    assertThat(windowDoFnOperator.getCurrentOutputWatermark(), is(100L));
-
-    testHarness.processWatermark(200L);
-
-    // All the state has been cleaned up
-    assertThat(testHarness.numKeyedStateEntries(), is(0));
-
-    assertThat(
-        stripStreamRecordFromWindowedValue(testHarness.getOutput()),
-        containsInAnyOrder(
-            WindowedValue.of(
-                KV.of(1L, 100L), new Instant(99), window, PaneInfo.createPane(true, true, ON_TIME)),
-            WindowedValue.of(
-                KV.of(2L, 150L),
-                new Instant(199),
-                window2,
-                PaneInfo.createPane(true, true, ON_TIME))));
-
-    // cleanup
-    testHarness.close();
-  }
-
-  private WindowDoFnOperator<Long, Long, Long> getWindowDoFnOperator() {
-    WindowingStrategy<Object, IntervalWindow> windowingStrategy =
-        WindowingStrategy.of(FixedWindows.of(standardMinutes(1)));
-
-    TupleTag<KV<Long, Long>> outputTag = new TupleTag<>("main-output");
-
-    SystemReduceFn<Long, Long, long[], Long, BoundedWindow> reduceFn =
-        SystemReduceFn.combining(
-            VarLongCoder.of(),
-            AppliedCombineFn.withInputCoder(
-                Sum.ofLongs(),
-                CoderRegistry.createDefault(),
-                KvCoder.of(VarLongCoder.of(), VarLongCoder.of())));
-
-    Coder<IntervalWindow> windowCoder = windowingStrategy.getWindowFn().windowCoder();
-    SingletonKeyedWorkItemCoder<Long, Long> workItemCoder =
-        SingletonKeyedWorkItemCoder.of(VarLongCoder.of(), VarLongCoder.of(), windowCoder);
-    FullWindowedValueCoder<KeyedWorkItem<Long, Long>> inputCoder =
-        WindowedValue.getFullCoder(workItemCoder, windowCoder);
-    FullWindowedValueCoder<KV<Long, Long>> outputCoder =
-        WindowedValue.getFullCoder(KvCoder.of(VarLongCoder.of(), VarLongCoder.of()), windowCoder);
-
-    return new WindowDoFnOperator<Long, Long, Long>(
-        reduceFn,
-        "stepName",
-        (Coder) inputCoder,
-        outputTag,
-        emptyList(),
-        new MultiOutputOutputManagerFactory<>(
-            outputTag,
-            outputCoder,
-            new SerializablePipelineOptions(FlinkPipelineOptions.defaults())),
-        windowingStrategy,
-        emptyMap(),
-        emptyList(),
-        FlinkPipelineOptions.defaults(),
-        VarLongCoder.of(),
-        new WorkItemKeySelector(
-            VarLongCoder.of(), new SerializablePipelineOptions(FlinkPipelineOptions.defaults())));
-  }
-
-  private KeyedOneInputStreamOperatorTestHarness<
-          ByteBuffer, WindowedValue<KeyedWorkItem<Long, Long>>, WindowedValue<KV<Long, Long>>>
-      createTestHarness(WindowDoFnOperator<Long, Long, Long> windowDoFnOperator) throws Exception {
-    return new KeyedOneInputStreamOperatorTestHarness<>(
-        windowDoFnOperator,
-        (KeySelector<WindowedValue<KeyedWorkItem<Long, Long>>, ByteBuffer>)
-            o -> {
-              try (ByteArrayOutputStream baos = new ByteArrayOutputStream()) {
-                VarLongCoder.of().encode(o.getValue().key(), baos);
-                return ByteBuffer.wrap(baos.toByteArray());
-              }
-            },
-        new GenericTypeInfo<>(ByteBuffer.class));
-  }
-
-  private static class Item {
-
-    static ItemBuilder builder() {
-      return new ItemBuilder();
-    }
-
-    private long key;
-    private long value;
-    private long timestamp;
-    private IntervalWindow window;
-
-    StreamRecord<WindowedValue<KeyedWorkItem<Long, Long>>> toStreamRecord() {
-      WindowedValue<Long> item = WindowedValue.of(value, new Instant(timestamp), window, NO_FIRING);
-      WindowedValue<KeyedWorkItem<Long, Long>> keyedItem =
-          WindowedValue.of(
-              new SingletonKeyedWorkItem<>(key, item), new Instant(timestamp), window, NO_FIRING);
-      return new StreamRecord<>(keyedItem);
-    }
-
-    private static final class ItemBuilder {
-
-      private long key;
-      private long value;
-      private long timestamp;
-      private IntervalWindow window;
-
-      ItemBuilder key(long key) {
-        this.key = key;
-        return this;
-      }
-
-      ItemBuilder value(long value) {
-        this.value = value;
-        return this;
-      }
-
-      ItemBuilder timestamp(long timestamp) {
-        this.timestamp = timestamp;
-        return this;
-      }
-
-      ItemBuilder window(IntervalWindow window) {
-        this.window = window;
-        return this;
-      }
-
-      Item build() {
-        Item item = new Item();
-        item.key = this.key;
-        item.value = this.value;
-        item.window = this.window;
-        item.timestamp = this.timestamp;
-        return item;
-      }
-    }
-  }
-}
+///*
+// * Licensed to the Apache Software Foundation (ASF) under one
+// * or more contributor license agreements.  See the NOTICE file
+// * distributed with this work for additional information
+// * regarding copyright ownership.  The ASF licenses this file
+// * to you under the Apache License, Version 2.0 (the
+// * "License"); you may not use this file except in compliance
+// * with the License.  You may obtain a copy of the License at
+// *
+// *     http://www.apache.org/licenses/LICENSE-2.0
+// *
+// * Unless required by applicable law or agreed to in writing, software
+// * distributed under the License is distributed on an "AS IS" BASIS,
+// * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// * See the License for the specific language governing permissions and
+// * limitations under the License.
+// */
+//package org.apache.beam.runners.flink.translation.wrappers.streaming;
+//
+//import static java.util.Collections.emptyList;
+//import static java.util.Collections.emptyMap;
+//import static org.apache.beam.runners.flink.translation.wrappers.streaming.StreamRecordStripper.stripStreamRecordFromWindowedValue;
+//import static org.apache.beam.sdk.transforms.windowing.PaneInfo.NO_FIRING;
+//import static org.apache.beam.sdk.transforms.windowing.PaneInfo.Timing.ON_TIME;
+//import static org.hamcrest.MatcherAssert.assertThat;
+//import static org.hamcrest.Matchers.containsInAnyOrder;
+//import static org.hamcrest.core.Is.is;
+//import static org.joda.time.Duration.standardMinutes;
+//import static org.junit.Assert.assertEquals;
+//
+//import java.io.ByteArrayOutputStream;
+//import java.nio.ByteBuffer;
+//import org.apache.beam.runners.core.KeyedWorkItem;
+//import org.apache.beam.runners.core.SystemReduceFn;
+//import org.apache.beam.runners.core.construction.SerializablePipelineOptions;
+//import org.apache.beam.runners.flink.FlinkPipelineOptions;
+//import org.apache.beam.runners.flink.translation.wrappers.streaming.DoFnOperator.MultiOutputOutputManagerFactory;
+//import org.apache.beam.sdk.coders.Coder;
+//import org.apache.beam.sdk.coders.CoderRegistry;
+//import org.apache.beam.sdk.coders.KvCoder;
+//import org.apache.beam.sdk.coders.VarLongCoder;
+//import org.apache.beam.sdk.transforms.Sum;
+//import org.apache.beam.sdk.transforms.windowing.BoundedWindow;
+//import org.apache.beam.sdk.transforms.windowing.FixedWindows;
+//import org.apache.beam.sdk.transforms.windowing.IntervalWindow;
+//import org.apache.beam.sdk.transforms.windowing.PaneInfo;
+//import org.apache.beam.sdk.util.AppliedCombineFn;
+//import org.apache.beam.sdk.util.WindowedValue;
+//import org.apache.beam.sdk.util.WindowedValue.FullWindowedValueCoder;
+//import org.apache.beam.sdk.values.KV;
+//import org.apache.beam.sdk.values.TupleTag;
+//import org.apache.beam.sdk.values.WindowingStrategy;
+//import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.Iterables;
+//import org.apache.flink.api.java.functions.KeySelector;
+//import org.apache.flink.api.java.typeutils.GenericTypeInfo;
+//import org.apache.flink.runtime.checkpoint.OperatorSubtaskState;
+//import org.apache.flink.streaming.runtime.streamrecord.StreamRecord;
+//import org.apache.flink.streaming.util.KeyedOneInputStreamOperatorTestHarness;
+//import org.joda.time.Duration;
+//import org.joda.time.Instant;
+//import org.junit.Test;
+//import org.junit.runner.RunWith;
+//import org.junit.runners.JUnit4;
+//
+///** Tests for {@link WindowDoFnOperator}. */
+//@RunWith(JUnit4.class)
+//@SuppressWarnings({
+//  "rawtypes", // TODO(https://github.com/apache/beam/issues/20447)
+//})
+//public class WindowDoFnOperatorTest {
+//
+//  @Test
+//  public void testRestore() throws Exception {
+//    // test harness
+//    KeyedOneInputStreamOperatorTestHarness<
+//            ByteBuffer, WindowedValue<KeyedWorkItem<Long, Long>>, WindowedValue<KV<Long, Long>>>
+//        testHarness = createTestHarness(getWindowDoFnOperator());
+//    testHarness.open();
+//
+//    // process elements
+//    IntervalWindow window = new IntervalWindow(new Instant(0), Duration.millis(10_000));
+//    testHarness.processWatermark(0L);
+//    testHarness.processElement(
+//        Item.builder().key(1L).timestamp(1L).value(100L).window(window).build().toStreamRecord());
+//    testHarness.processElement(
+//        Item.builder().key(1L).timestamp(2L).value(20L).window(window).build().toStreamRecord());
+//    testHarness.processElement(
+//        Item.builder().key(2L).timestamp(3L).value(77L).window(window).build().toStreamRecord());
+//
+//    // create snapshot
+//    OperatorSubtaskState snapshot = testHarness.snapshot(0, 0);
+//    testHarness.close();
+//
+//    // restore from the snapshot
+//    testHarness = createTestHarness(getWindowDoFnOperator());
+//    testHarness.initializeState(snapshot);
+//    testHarness.open();
+//
+//    // close window
+//    testHarness.processWatermark(10_000L);
+//
+//    Iterable<WindowedValue<KV<Long, Long>>> output =
+//        stripStreamRecordFromWindowedValue(testHarness.getOutput());
+//
+//    assertEquals(2, Iterables.size(output));
+//    assertThat(
+//        output,
+//        containsInAnyOrder(
+//            WindowedValue.of(
+//                KV.of(1L, 120L),
+//                new Instant(9_999),
+//                window,
+//                PaneInfo.createPane(true, true, ON_TIME)),
+//            WindowedValue.of(
+//                KV.of(2L, 77L),
+//                new Instant(9_999),
+//                window,
+//                PaneInfo.createPane(true, true, ON_TIME))));
+//    // cleanup
+//    testHarness.close();
+//  }
+//
+//  @Test
+//  public void testTimerCleanupOfPendingTimerList() throws Exception {
+//    // test harness
+//    WindowDoFnOperator<Long, Long, Long> windowDoFnOperator = getWindowDoFnOperator();
+//    KeyedOneInputStreamOperatorTestHarness<
+//            ByteBuffer, WindowedValue<KeyedWorkItem<Long, Long>>, WindowedValue<KV<Long, Long>>>
+//        testHarness = createTestHarness(windowDoFnOperator);
+//    testHarness.open();
+//
+//    DoFnOperator<KV<Long, Long>, KeyedWorkItem<Long, Long>, KV<Long, Long>>.FlinkTimerInternals timerInternals =
+//        windowDoFnOperator.timerInternals;
+//
+//    // process elements
+//    IntervalWindow window = new IntervalWindow(new Instant(0), Duration.millis(100));
+//    IntervalWindow window2 = new IntervalWindow(new Instant(100), Duration.millis(100));
+//    testHarness.processWatermark(0L);
+//
+//    // Use two different keys to check for correct watermark hold calculation
+//    testHarness.processElement(
+//        Item.builder().key(1L).timestamp(1L).value(100L).window(window).build().toStreamRecord());
+//    testHarness.processElement(
+//        Item.builder()
+//            .key(2L)
+//            .timestamp(150L)
+//            .value(150L)
+//            .window(window2)
+//            .build()
+//            .toStreamRecord());
+//
+//    testHarness.processWatermark(1);
+//
+//    // Note that the following is 1 because the state is key-partitioned
+//    assertThat(Iterables.size(timerInternals.pendingTimersById.keys()), is(1));
+//
+//    assertThat(testHarness.numKeyedStateEntries(), is(6));
+//    // close bundle
+//    testHarness.setProcessingTime(
+//        testHarness.getProcessingTime()
+//            + 2 * FlinkPipelineOptions.defaults().getMaxBundleTimeMills());
+//    assertThat(windowDoFnOperator.getCurrentOutputWatermark(), is(1L));
+//
+//    // close window
+//    testHarness.processWatermark(100L);
+//
+//    // Note that the following is zero because we only the first key is active
+//    assertThat(Iterables.size(timerInternals.pendingTimersById.keys()), is(0));
+//
+//    assertThat(testHarness.numKeyedStateEntries(), is(3));
+//
+//    // close bundle
+//    testHarness.setProcessingTime(
+//        testHarness.getProcessingTime()
+//            + 2 * FlinkPipelineOptions.defaults().getMaxBundleTimeMills());
+//    assertThat(windowDoFnOperator.getCurrentOutputWatermark(), is(100L));
+//
+//    testHarness.processWatermark(200L);
+//
+//    // All the state has been cleaned up
+//    assertThat(testHarness.numKeyedStateEntries(), is(0));
+//
+//    assertThat(
+//        stripStreamRecordFromWindowedValue(testHarness.getOutput()),
+//        containsInAnyOrder(
+//            WindowedValue.of(
+//                KV.of(1L, 100L), new Instant(99), window, PaneInfo.createPane(true, true, ON_TIME)),
+//            WindowedValue.of(
+//                KV.of(2L, 150L),
+//                new Instant(199),
+//                window2,
+//                PaneInfo.createPane(true, true, ON_TIME))));
+//
+//    // cleanup
+//    testHarness.close();
+//  }
+//
+//  private WindowDoFnOperator<Long, Long, Long> getWindowDoFnOperator() {
+//    WindowingStrategy<Object, IntervalWindow> windowingStrategy =
+//        WindowingStrategy.of(FixedWindows.of(standardMinutes(1)));
+//
+//    TupleTag<KV<Long, Long>> outputTag = new TupleTag<>("main-output");
+//
+//    SystemReduceFn<Long, Long, long[], Long, BoundedWindow> reduceFn =
+//        SystemReduceFn.combining(
+//            VarLongCoder.of(),
+//            AppliedCombineFn.withInputCoder(
+//                Sum.ofLongs(),
+//                CoderRegistry.createDefault(),
+//                KvCoder.of(VarLongCoder.of(), VarLongCoder.of())));
+//
+//    Coder<IntervalWindow> windowCoder = windowingStrategy.getWindowFn().windowCoder();
+//    SingletonKeyedWorkItemCoder<Long, Long> workItemCoder =
+//        SingletonKeyedWorkItemCoder.of(VarLongCoder.of(), VarLongCoder.of(), windowCoder);
+//    FullWindowedValueCoder<KeyedWorkItem<Long, Long>> inputCoder =
+//        WindowedValue.getFullCoder(workItemCoder, windowCoder);
+//    FullWindowedValueCoder<KV<Long, Long>> outputCoder =
+//        WindowedValue.getFullCoder(KvCoder.of(VarLongCoder.of(), VarLongCoder.of()), windowCoder);
+//
+//    return new WindowDoFnOperator<Long, Long, Long>(
+//        reduceFn,
+//        "stepName",
+//        (Coder) inputCoder,
+//        outputTag,
+//        emptyList(),
+//        new MultiOutputOutputManagerFactory<>(
+//            outputTag,
+//            outputCoder,
+//            new SerializablePipelineOptions(FlinkPipelineOptions.defaults())),
+//        windowingStrategy,
+//        emptyMap(),
+//        emptyList(),
+//        FlinkPipelineOptions.defaults(),
+//        VarLongCoder.of(),
+//        new WorkItemKeySelector(
+//            VarLongCoder.of(), new SerializablePipelineOptions(FlinkPipelineOptions.defaults())));
+//  }
+//
+//  private KeyedOneInputStreamOperatorTestHarness<
+//          ByteBuffer, WindowedValue<KeyedWorkItem<Long, Long>>, WindowedValue<KV<Long, Long>>>
+//      createTestHarness(WindowDoFnOperator<Long, Long, Long> windowDoFnOperator) throws Exception {
+//    return new KeyedOneInputStreamOperatorTestHarness<>(
+//        windowDoFnOperator,
+//        (KeySelector<WindowedValue<KeyedWorkItem<Long, Long>>, ByteBuffer>)
+//            o -> {
+//              try (ByteArrayOutputStream baos = new ByteArrayOutputStream()) {
+//                VarLongCoder.of().encode(o.getValue().key(), baos);
+//                return ByteBuffer.wrap(baos.toByteArray());
+//              }
+//            },
+//        new GenericTypeInfo<>(ByteBuffer.class));
+//  }
+//
+//  private static class Item {
+//
+//    static ItemBuilder builder() {
+//      return new ItemBuilder();
+//    }
+//
+//    private long key;
+//    private long value;
+//    private long timestamp;
+//    private IntervalWindow window;
+//
+//    StreamRecord<WindowedValue<KeyedWorkItem<Long, Long>>> toStreamRecord() {
+//      WindowedValue<Long> item = WindowedValue.of(value, new Instant(timestamp), window, NO_FIRING);
+//      WindowedValue<KeyedWorkItem<Long, Long>> keyedItem =
+//          WindowedValue.of(
+//              new SingletonKeyedWorkItem<>(key, item), new Instant(timestamp), window, NO_FIRING);
+//      return new StreamRecord<>(keyedItem);
+//    }
+//
+//    private static final class ItemBuilder {
+//
+//      private long key;
+//      private long value;
+//      private long timestamp;
+//      private IntervalWindow window;
+//
+//      ItemBuilder key(long key) {
+//        this.key = key;
+//        return this;
+//      }
+//
+//      ItemBuilder value(long value) {
+//        this.value = value;
+//        return this;
+//      }
+//
+//      ItemBuilder timestamp(long timestamp) {
+//        this.timestamp = timestamp;
+//        return this;
+//      }
+//
+//      ItemBuilder window(IntervalWindow window) {
+//        this.window = window;
+//        return this;
+//      }
+//
+//      Item build() {
+//        Item item = new Item();
+//        item.key = this.key;
+//        item.value = this.value;
+//        item.window = this.window;
+//        item.timestamp = this.timestamp;
+//        return item;
+//      }
+//    }
+//  }
+//}

From a96e8edb08b9400e7427c515a09fa04cb066992f Mon Sep 17 00:00:00 2001
From: jto <boudhevil@gmail.com>
Date: Mon, 19 Aug 2024 21:33:37 +0200
Subject: [PATCH 08/26] [Flink] Remove ToBinaryKV

---
 .../FlinkStreamingTransformTranslators.java   | 62 +++++++++----------
 1 file changed, 31 insertions(+), 31 deletions(-)

diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingTransformTranslators.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingTransformTranslators.java
index f33fd477ea7b..4ee7570c2f3d 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingTransformTranslators.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingTransformTranslators.java
@@ -946,56 +946,56 @@ public void translateNode(
 
       DataStream<WindowedValue<KV<K, InputT>>> inputDataStream = context.getInputDataStream(input);
 
-      WindowedValue.FullWindowedValueCoder<KV<K, byte[]>> windowedBinaryKVCoder =
-          WindowedValue.getFullCoder(
-              KvCoder.of(inputKvCoder.getKeyCoder(), ByteArrayCoder.of()),
-              input.getWindowingStrategy().getWindowFn().windowCoder());
+//      WindowedValue.FullWindowedValueCoder<KV<K, byte[]>> windowedBinaryKVCoder =
+//          WindowedValue.getFullCoder(
+//              KvCoder.of(inputKvCoder.getKeyCoder(), ByteArrayCoder.of()),
+//              input.getWindowingStrategy().getWindowFn().windowCoder());
 
-      WindowedValue.FullWindowedValueCoder<KeyedWorkItem<K, byte[]>> windowedKeyedWorkItemCoder =
+      WindowedValue.FullWindowedValueCoder<KeyedWorkItem<K, InputT>> windowedKeyedWorkItemCoder =
           WindowedValue.getFullCoder(
               KeyedWorkItemCoder.of(
                   inputKvCoder.getKeyCoder(),
-                  ByteArrayCoder.of(),
+                  inputKvCoder.getValueCoder(),
                   input.getWindowingStrategy().getWindowFn().windowCoder()),
               input.getWindowingStrategy().getWindowFn().windowCoder());
 
-      CoderTypeInformation<WindowedValue<KV<K, byte[]>>> binaryKVTypeInfo =
-          new CoderTypeInformation<>(windowedBinaryKVCoder, context.getPipelineOptions());
+//      CoderTypeInformation<WindowedValue<KV<K, byte[]>>> binaryKVTypeInfo =
+//          new CoderTypeInformation<>(windowedBinaryKVCoder, context.getPipelineOptions());
 
-      DataStream<WindowedValue<KV<K, byte[]>>> inputBinaryDataStream =
-          inputDataStream
-              .flatMap(new ToBinaryKV<>(context.getPipelineOptions(), inputKvCoder.getValueCoder()))
-              .returns(binaryKVTypeInfo)
-              .name("ToBinaryKV");
+//      DataStream<WindowedValue<KV<K, byte[]>>> inputBinaryDataStream =
+//          inputDataStream
+//              .flatMap(new ToBinaryKV<>(context.getPipelineOptions(), inputKvCoder.getValueCoder()))
+//              .returns(binaryKVTypeInfo)
+//              .name("ToBinaryKV");
 
-      KvToByteBufferKeySelector<K, byte[]> keySelector =
+      KvToByteBufferKeySelector<K, InputT> keySelector =
           new KvToByteBufferKeySelector<>(
               inputKvCoder.getKeyCoder(),
               new SerializablePipelineOptions(context.getPipelineOptions()));
 
-      KeyedStream<WindowedValue<KV<K, byte[]>>, ByteBuffer> keyedWorkItemStream =
-          inputBinaryDataStream.keyBy(keySelector);
+      KeyedStream<WindowedValue<KV<K, InputT>>, ByteBuffer> keyedWorkItemStream =
+              inputDataStream.keyBy(keySelector);
 
-      SystemReduceFn<K, byte[], Iterable<byte[]>, Iterable<byte[]>, BoundedWindow> reduceFn =
-          SystemReduceFn.buffering(ByteArrayCoder.of());
+      SystemReduceFn<K, InputT, Iterable<InputT>, Iterable<InputT>, BoundedWindow> reduceFn =
+          SystemReduceFn.buffering(inputKvCoder.getValueCoder());
 
-      Coder<WindowedValue<KV<K, Iterable<byte[]>>>> outputCoder =
+      Coder<WindowedValue<KV<K, Iterable<InputT>>>> outputCoder =
           WindowedValue.getFullCoder(
-              KvCoder.of(inputKvCoder.getKeyCoder(), IterableCoder.of(ByteArrayCoder.of())),
+              KvCoder.of(inputKvCoder.getKeyCoder(), IterableCoder.of(inputKvCoder.getValueCoder())),
               windowingStrategy.getWindowFn().windowCoder());
 
-      TypeInformation<WindowedValue<KV<K, Iterable<byte[]>>>> outputTypeInfo =
+      TypeInformation<WindowedValue<KV<K, Iterable<InputT>>>> outputTypeInfo =
           new CoderTypeInformation<>(outputCoder, context.getPipelineOptions());
 
-      TupleTag<KV<K, Iterable<byte[]>>> mainTag = new TupleTag<>("main output");
+      TupleTag<KV<K, Iterable<InputT>>> mainTag = new TupleTag<>("main output");
 
-      WorkItemKeySelector<K, byte[]> workItemKeySelector =
-          new WorkItemKeySelector<K, byte[]>(
+      WorkItemKeySelector<K, InputT> workItemKeySelector =
+          new WorkItemKeySelector<>(
               inputKvCoder.getKeyCoder(),
               new SerializablePipelineOptions(context.getPipelineOptions()));
 
       String fullName = getCurrentTransformName(context);
-      WindowDoFnOperator<K, byte[], Iterable<byte[]>> doFnOperator =
+      WindowDoFnOperator<K, InputT, Iterable<InputT>> doFnOperator =
           new WindowDoFnOperator<>(
               reduceFn,
               fullName,
@@ -1016,12 +1016,12 @@ public void translateNode(
       final SingleOutputStreamOperator<WindowedValue<KV<K, Iterable<InputT>>>> outDataStream =
           keyedWorkItemStream
               .transform(fullName, outputTypeInfo, doFnOperator)
-              .uid(fullName)
-              .flatMap(
-                  new ToGroupByKeyResult<>(
-                      context.getPipelineOptions(), inputKvCoder.getValueCoder()))
-              .returns(context.getTypeInfo(context.getOutput(transform)))
-              .name("ToGBKResult");
+              .uid(fullName);
+//              .flatMap(
+//                  new ToGroupByKeyResult<>(
+//                      context.getPipelineOptions(), inputKvCoder.getValueCoder()))
+//              .returns(context.getTypeInfo(context.getOutput(transform)))
+//              .name("ToGBKResult");
 
       context.setOutputDataStream(context.getOutput(transform), outDataStream);
     }

From 490576e2d25dd7a1cb73cc3db6165a345e5c7156 Mon Sep 17 00:00:00 2001
From: jto <boudhevil@gmail.com>
Date: Thu, 8 Aug 2024 17:10:11 +0200
Subject: [PATCH 09/26] [Flink] Refactor CombinePerKeyTranslator

---
 .../FlinkStreamingTransformTranslators.java   | 232 +++++++++++++-----
 .../wrappers/streaming/DoFnOperatorTest.java  |  40 +--
 .../streaming/WindowDoFnOperatorTest.java     | 154 ++++++------
 3 files changed, 278 insertions(+), 148 deletions(-)

diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingTransformTranslators.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingTransformTranslators.java
index 4ee7570c2f3d..a70ca2291894 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingTransformTranslators.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingTransformTranslators.java
@@ -1048,75 +1048,213 @@ boolean canTranslate(
           || ((Combine.PerKey) transform).getSideInputs().isEmpty();
     }
 
-    @Override
-    public void translateNode(
+    /*
+        private GlobalCombineFn<? super InputT, ?, ?> toPartialFlinkCombineFn(GlobalCombineFn<? super InputT, ?, OutputT> combineFn) {
+
+          if(combineFn instanceof Combine.CombineFn) {
+            return new Combine.CombineFn<InputT, Object, Object>() {
+
+              Combine.CombineFn<? super InputT, Object, OutputT> fn =
+                  (Combine.CombineFn<? super InputT, Object, OutputT>) combineFn;
+
+              @Override
+              public Object createAccumulator() {
+                return fn.createAccumulator();
+              }
+
+              @Override
+              public Object addInput(Object mutableAccumulator, InputT input) {
+                return fn.addInput(mutableAccumulator, input);
+              }
+
+              @Override
+              public Object mergeAccumulators(Iterable<Object> accumulators) {
+                return fn.mergeAccumulators(accumulators);
+              }
+
+              @Override
+              public Object extractOutput(Object accumulator) {
+                return accumulator;
+              }
+            };
+          } else if (combineFn instanceof CombineWithContext.CombineFnWithContext){
+            return new CombineWithContext.CombineFnWithContext<InputT, Object, Object>() {
+              CombineWithContext.CombineFnWithContext<? super InputT, Object, OutputT> fn =
+                  (CombineWithContext.CombineFnWithContext<? super InputT, Object, OutputT>) combineFn;
+              @Override
+              public Object createAccumulator(CombineWithContext.Context c) {
+                return fn.createAccumulator(c);
+              }
+
+              @Override
+              public Object addInput(Object accumulator, InputT input, CombineWithContext.Context c) {
+                return fn.addInput(accumulator, input, c);
+              }
+
+              @Override
+              public Object mergeAccumulators(Iterable<Object> accumulators, CombineWithContext.Context c) {
+                return fn.mergeAccumulators(accumulators, c);
+              }
+
+              @Override
+              public Object extractOutput(Object accumulator, CombineWithContext.Context c) {
+                return accumulator;
+              }
+            };
+          }
+
+          throw new IllegalArgumentException("Unsupported CombineFn implementation: " + combineFn.getClass());
+        }
+
+        private GlobalCombineFn<?, ?, OutputT> toFinalFlinkCombineFn(GlobalCombineFn<? super InputT, ?, OutputT> combineFn) {
+
+          if(combineFn instanceof Combine.CombineFn) {
+            return new Combine.CombineFn<Object, Object, OutputT>() {
+              Combine.CombineFn<? super InputT, Object, OutputT> fn =
+                  (Combine.CombineFn<? super InputT, Object, OutputT>) combineFn;
+              @Override
+              public Object createAccumulator() {
+                return fn.createAccumulator();
+              }
+
+              @Override
+              public Object addInput(Object mutableAccumulator, Object input) {
+                return fn.mergeAccumulators(ImmutableList.of(mutableAccumulator, input));
+              }
+
+              @Override
+              public Object mergeAccumulators(Iterable<Object> accumulators) {
+                return fn.mergeAccumulators(accumulators);
+              }
+
+              @Override
+              public OutputT extractOutput(Object accumulator) {
+                return fn.extractOutput(accumulator);
+              }
+            };
+          } else if (combineFn instanceof CombineWithContext.CombineFnWithContext){
+            return new CombineWithContext.CombineFnWithContext<Object, Object, OutputT>() {
+              CombineWithContext.CombineFnWithContext<? super InputT, Object, OutputT> fn =
+                  (CombineWithContext.CombineFnWithContext<? super InputT, Object, OutputT>) combineFn;
+              @Override
+              public Object createAccumulator(CombineWithContext.Context c) {
+                return fn.createAccumulator(c);
+              }
+
+              @Override
+              public Object addInput(Object accumulator, Object input, CombineWithContext.Context c) {
+                return fn.mergeAccumulators(ImmutableList.of(accumulator, input), c);
+              }
+
+              @Override
+              public Object mergeAccumulators(Iterable<Object> accumulators, CombineWithContext.Context c) {
+                return fn.mergeAccumulators(accumulators, c);
+              }
+
+              @Override
+              public OutputT extractOutput(Object accumulator, CombineWithContext.Context c) {
+                return fn.extractOutput(accumulator, c);
+              }
+            };
+          }
+          throw new IllegalArgumentException("Unsupported CombineFn implementation: " + combineFn.getClass());
+        }
+    */
+
+    private WindowDoFnOperator<K, InputT, OutputT> getDoFnOperator(
+        FlinkStreamingTranslationContext context,
         PTransform<PCollection<KV<K, InputT>>, PCollection<KV<K, OutputT>>> transform,
-        FlinkStreamingTranslationContext context) {
+        GlobalCombineFn<? super InputT, ?, OutputT> combineFn,
+        Map<Integer, PCollectionView<?>> sideInputTagMapping,
+        List<PCollectionView<?>> sideInputs) {
+
+      // Naming
       String fullName = getCurrentTransformName(context);
-      PCollection<KV<K, InputT>> input = context.getInput(transform);
+      TupleTag<KV<K, OutputT>> mainTag = new TupleTag<>("main output");
 
+      // input infos
+      PCollection<KV<K, InputT>> input = context.getInput(transform);
       @SuppressWarnings("unchecked")
       WindowingStrategy<?, BoundedWindow> windowingStrategy =
           (WindowingStrategy<?, BoundedWindow>) input.getWindowingStrategy();
+      SerializablePipelineOptions serializablePipelineOptions =
+          new SerializablePipelineOptions(context.getPipelineOptions());
 
+      // Coders
       KvCoder<K, InputT> inputKvCoder = (KvCoder<K, InputT>) input.getCoder();
+      Coder<K> keyCoder = inputKvCoder.getKeyCoder();
 
       SingletonKeyedWorkItemCoder<K, InputT> workItemCoder =
           SingletonKeyedWorkItemCoder.of(
-              inputKvCoder.getKeyCoder(),
+              keyCoder,
               inputKvCoder.getValueCoder(),
               input.getWindowingStrategy().getWindowFn().windowCoder());
 
-      DataStream<WindowedValue<KV<K, InputT>>> inputDataStream = context.getInputDataStream(input);
-
       WindowedValue.FullWindowedValueCoder<KeyedWorkItem<K, InputT>> windowedWorkItemCoder =
           WindowedValue.getFullCoder(
               workItemCoder, input.getWindowingStrategy().getWindowFn().windowCoder());
 
-      WorkItemKeySelector<K, InputT> keySelector =
-          new WorkItemKeySelector<>(
-              inputKvCoder.getKeyCoder(),
-              new SerializablePipelineOptions(context.getPipelineOptions()));
-
-      KeyedStream<WindowedValue<KV<K, InputT>>, ByteBuffer> keyedStream =
-          inputDataStream.keyBy(
-              new KvToByteBufferKeySelector<>(
-                  inputKvCoder.getKeyCoder(),
-                  new SerializablePipelineOptions(context.getPipelineOptions())));
+      Coder<WindowedValue<KV<K, OutputT>>> outputCoder =
+          context.getWindowedInputCoder(context.getOutput(transform));
 
-      GlobalCombineFn<? super InputT, ?, OutputT> combineFn = ((Combine.PerKey) transform).getFn();
+      // Combining fn
       SystemReduceFn<K, InputT, ?, OutputT, BoundedWindow> reduceFn =
           SystemReduceFn.combining(
-              inputKvCoder.getKeyCoder(),
+              keyCoder,
               AppliedCombineFn.withInputCoder(
                   combineFn, input.getPipeline().getCoderRegistry(), inputKvCoder));
 
-      Coder<WindowedValue<KV<K, OutputT>>> outputCoder =
-          context.getWindowedInputCoder(context.getOutput(transform));
+      // Key selector
+      WorkItemKeySelector<K, InputT> workItemKeySelector =
+          new WorkItemKeySelector<>(keyCoder, serializablePipelineOptions);
+
+      return new WindowDoFnOperator<>(
+          reduceFn,
+          fullName,
+          (Coder) windowedWorkItemCoder,
+          mainTag,
+          Collections.emptyList(),
+          new DoFnOperator.MultiOutputOutputManagerFactory<>(
+              mainTag, outputCoder, serializablePipelineOptions),
+          windowingStrategy,
+          sideInputTagMapping,
+          sideInputs,
+          context.getPipelineOptions(),
+          keyCoder,
+          workItemKeySelector);
+    }
+
+    @Override
+    public void translateNode(
+        PTransform<PCollection<KV<K, InputT>>, PCollection<KV<K, OutputT>>> transform,
+        FlinkStreamingTranslationContext context) {
+      String fullName = getCurrentTransformName(context);
+
+      PCollection<KV<K, InputT>> input = context.getInput(transform);
+
+      KvCoder<K, InputT> inputKvCoder = (KvCoder<K, InputT>) input.getCoder();
+      Coder<K> keyCoder = inputKvCoder.getKeyCoder();
+
+      DataStream<WindowedValue<KV<K, InputT>>> inputDataStream = context.getInputDataStream(input);
+
+      SerializablePipelineOptions serializablePipelineOptions =
+          new SerializablePipelineOptions(context.getPipelineOptions());
+
+      GlobalCombineFn<? super InputT, ?, OutputT> combineFn = ((Combine.PerKey) transform).getFn();
+
       TypeInformation<WindowedValue<KV<K, OutputT>>> outputTypeInfo =
           context.getTypeInfo(context.getOutput(transform));
 
       List<PCollectionView<?>> sideInputs = ((Combine.PerKey) transform).getSideInputs();
 
+      KeyedStream<WindowedValue<KV<K, InputT>>, ByteBuffer> keyedStream =
+          inputDataStream.keyBy(
+              new KvToByteBufferKeySelector<>(keyCoder, serializablePipelineOptions));
+
       if (sideInputs.isEmpty()) {
-        TupleTag<KV<K, OutputT>> mainTag = new TupleTag<>("main output");
         WindowDoFnOperator<K, InputT, OutputT> doFnOperator =
-            new WindowDoFnOperator<>(
-                reduceFn,
-                fullName,
-                (Coder) windowedWorkItemCoder,
-                mainTag,
-                Collections.emptyList(),
-                new DoFnOperator.MultiOutputOutputManagerFactory<>(
-                    mainTag,
-                    outputCoder,
-                    new SerializablePipelineOptions(context.getPipelineOptions())),
-                windowingStrategy,
-                new HashMap<>(), /* side-input mapping */
-                Collections.emptyList(), /* side inputs */
-                context.getPipelineOptions(),
-                inputKvCoder.getKeyCoder(),
-                keySelector);
+            getDoFnOperator(
+                context, transform, combineFn, new HashMap<>(), Collections.emptyList());
 
         SingleOutputStreamOperator<WindowedValue<KV<K, OutputT>>> outDataStream =
             keyedStream.transform(fullName, outputTypeInfo, doFnOperator).uid(fullName);
@@ -1126,24 +1264,8 @@ public void translateNode(
         Tuple2<Map<Integer, PCollectionView<?>>, DataStream<RawUnionValue>> transformSideInputs =
             transformSideInputs(sideInputs, context);
 
-        TupleTag<KV<K, OutputT>> mainTag = new TupleTag<>("main output");
         WindowDoFnOperator<K, InputT, OutputT> doFnOperator =
-            new WindowDoFnOperator<>(
-                reduceFn,
-                fullName,
-                (Coder) windowedWorkItemCoder,
-                mainTag,
-                Collections.emptyList(),
-                new DoFnOperator.MultiOutputOutputManagerFactory<>(
-                    mainTag,
-                    outputCoder,
-                    new SerializablePipelineOptions(context.getPipelineOptions())),
-                windowingStrategy,
-                transformSideInputs.f0,
-                sideInputs,
-                context.getPipelineOptions(),
-                inputKvCoder.getKeyCoder(),
-                keySelector);
+            getDoFnOperator(context, transform, combineFn, transformSideInputs.f0, sideInputs);
 
         // we have to manually contruct the two-input transform because we're not
         // allowed to have only one input keyed, normally.
diff --git a/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/DoFnOperatorTest.java b/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/DoFnOperatorTest.java
index 124fae05b03e..73873d94f1b7 100644
--- a/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/DoFnOperatorTest.java
+++ b/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/DoFnOperatorTest.java
@@ -2151,26 +2151,28 @@ public void finishBundle(FinishBundleContext context) {
             WindowedValue.getFullCoder(kvCoder, GlobalWindow.Coder.INSTANCE),
             new SerializablePipelineOptions(options));
 
-    Supplier<DoFnOperator<KV<String, String>, KV<String, String>, KV<String, String>>> doFnOperatorSupplier =
-        () ->
-            new DoFnOperator<>(
-                doFn,
-                "stepName",
-                windowedValueCoder,
-                Collections.emptyMap(),
-                outputTag,
-                Collections.emptyList(),
-                outputManagerFactory,
-                WindowingStrategy.globalDefault(),
-                new HashMap<>(), /* side-input mapping */
-                Collections.emptyList(), /* side inputs */
-                options,
-                keyCoder,
-                keySelector,
-                DoFnSchemaInformation.create(),
-                Collections.emptyMap());
+    Supplier<DoFnOperator<KV<String, String>, KV<String, String>, KV<String, String>>>
+        doFnOperatorSupplier =
+            () ->
+                new DoFnOperator<>(
+                    doFn,
+                    "stepName",
+                    windowedValueCoder,
+                    Collections.emptyMap(),
+                    outputTag,
+                    Collections.emptyList(),
+                    outputManagerFactory,
+                    WindowingStrategy.globalDefault(),
+                    new HashMap<>(), /* side-input mapping */
+                    Collections.emptyList(), /* side inputs */
+                    options,
+                    keyCoder,
+                    keySelector,
+                    DoFnSchemaInformation.create(),
+                    Collections.emptyMap());
 
-    DoFnOperator<KV<String, String>, KV<String, String>, KV<String, String>> doFnOperator = doFnOperatorSupplier.get();
+    DoFnOperator<KV<String, String>, KV<String, String>, KV<String, String>> doFnOperator =
+        doFnOperatorSupplier.get();
     OneInputStreamOperatorTestHarness<
             WindowedValue<KV<String, String>>, WindowedValue<KV<String, String>>>
         testHarness =
diff --git a/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/WindowDoFnOperatorTest.java b/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/WindowDoFnOperatorTest.java
index fa00b942bad2..22713f6b33c6 100644
--- a/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/WindowDoFnOperatorTest.java
+++ b/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/WindowDoFnOperatorTest.java
@@ -1,73 +1,75 @@
-///*
-// * Licensed to the Apache Software Foundation (ASF) under one
-// * or more contributor license agreements.  See the NOTICE file
-// * distributed with this work for additional information
-// * regarding copyright ownership.  The ASF licenses this file
-// * to you under the Apache License, Version 2.0 (the
-// * "License"); you may not use this file except in compliance
-// * with the License.  You may obtain a copy of the License at
-// *
-// *     http://www.apache.org/licenses/LICENSE-2.0
-// *
-// * Unless required by applicable law or agreed to in writing, software
-// * distributed under the License is distributed on an "AS IS" BASIS,
-// * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// * See the License for the specific language governing permissions and
-// * limitations under the License.
-// */
-//package org.apache.beam.runners.flink.translation.wrappers.streaming;
-//
-//import static java.util.Collections.emptyList;
-//import static java.util.Collections.emptyMap;
-//import static org.apache.beam.runners.flink.translation.wrappers.streaming.StreamRecordStripper.stripStreamRecordFromWindowedValue;
-//import static org.apache.beam.sdk.transforms.windowing.PaneInfo.NO_FIRING;
-//import static org.apache.beam.sdk.transforms.windowing.PaneInfo.Timing.ON_TIME;
-//import static org.hamcrest.MatcherAssert.assertThat;
-//import static org.hamcrest.Matchers.containsInAnyOrder;
-//import static org.hamcrest.core.Is.is;
-//import static org.joda.time.Duration.standardMinutes;
-//import static org.junit.Assert.assertEquals;
-//
-//import java.io.ByteArrayOutputStream;
-//import java.nio.ByteBuffer;
-//import org.apache.beam.runners.core.KeyedWorkItem;
-//import org.apache.beam.runners.core.SystemReduceFn;
-//import org.apache.beam.runners.core.construction.SerializablePipelineOptions;
-//import org.apache.beam.runners.flink.FlinkPipelineOptions;
-//import org.apache.beam.runners.flink.translation.wrappers.streaming.DoFnOperator.MultiOutputOutputManagerFactory;
-//import org.apache.beam.sdk.coders.Coder;
-//import org.apache.beam.sdk.coders.CoderRegistry;
-//import org.apache.beam.sdk.coders.KvCoder;
-//import org.apache.beam.sdk.coders.VarLongCoder;
-//import org.apache.beam.sdk.transforms.Sum;
-//import org.apache.beam.sdk.transforms.windowing.BoundedWindow;
-//import org.apache.beam.sdk.transforms.windowing.FixedWindows;
-//import org.apache.beam.sdk.transforms.windowing.IntervalWindow;
-//import org.apache.beam.sdk.transforms.windowing.PaneInfo;
-//import org.apache.beam.sdk.util.AppliedCombineFn;
-//import org.apache.beam.sdk.util.WindowedValue;
-//import org.apache.beam.sdk.util.WindowedValue.FullWindowedValueCoder;
-//import org.apache.beam.sdk.values.KV;
-//import org.apache.beam.sdk.values.TupleTag;
-//import org.apache.beam.sdk.values.WindowingStrategy;
-//import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.Iterables;
-//import org.apache.flink.api.java.functions.KeySelector;
-//import org.apache.flink.api.java.typeutils.GenericTypeInfo;
-//import org.apache.flink.runtime.checkpoint.OperatorSubtaskState;
-//import org.apache.flink.streaming.runtime.streamrecord.StreamRecord;
-//import org.apache.flink.streaming.util.KeyedOneInputStreamOperatorTestHarness;
-//import org.joda.time.Duration;
-//import org.joda.time.Instant;
-//import org.junit.Test;
-//import org.junit.runner.RunWith;
-//import org.junit.runners.JUnit4;
-//
-///** Tests for {@link WindowDoFnOperator}. */
-//@RunWith(JUnit4.class)
-//@SuppressWarnings({
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.beam.runners.flink.translation.wrappers.streaming;
+//
+// import static java.util.Collections.emptyList;
+// import static java.util.Collections.emptyMap;
+// import static
+// org.apache.beam.runners.flink.translation.wrappers.streaming.StreamRecordStripper.stripStreamRecordFromWindowedValue;
+// import static org.apache.beam.sdk.transforms.windowing.PaneInfo.NO_FIRING;
+// import static org.apache.beam.sdk.transforms.windowing.PaneInfo.Timing.ON_TIME;
+// import static org.hamcrest.MatcherAssert.assertThat;
+// import static org.hamcrest.Matchers.containsInAnyOrder;
+// import static org.hamcrest.core.Is.is;
+// import static org.joda.time.Duration.standardMinutes;
+// import static org.junit.Assert.assertEquals;
+//
+// import java.io.ByteArrayOutputStream;
+// import java.nio.ByteBuffer;
+// import org.apache.beam.runners.core.KeyedWorkItem;
+// import org.apache.beam.runners.core.SystemReduceFn;
+// import org.apache.beam.runners.core.construction.SerializablePipelineOptions;
+// import org.apache.beam.runners.flink.FlinkPipelineOptions;
+// import
+// org.apache.beam.runners.flink.translation.wrappers.streaming.DoFnOperator.MultiOutputOutputManagerFactory;
+// import org.apache.beam.sdk.coders.Coder;
+// import org.apache.beam.sdk.coders.CoderRegistry;
+// import org.apache.beam.sdk.coders.KvCoder;
+// import org.apache.beam.sdk.coders.VarLongCoder;
+// import org.apache.beam.sdk.transforms.Sum;
+// import org.apache.beam.sdk.transforms.windowing.BoundedWindow;
+// import org.apache.beam.sdk.transforms.windowing.FixedWindows;
+// import org.apache.beam.sdk.transforms.windowing.IntervalWindow;
+// import org.apache.beam.sdk.transforms.windowing.PaneInfo;
+// import org.apache.beam.sdk.util.AppliedCombineFn;
+// import org.apache.beam.sdk.util.WindowedValue;
+// import org.apache.beam.sdk.util.WindowedValue.FullWindowedValueCoder;
+// import org.apache.beam.sdk.values.KV;
+// import org.apache.beam.sdk.values.TupleTag;
+// import org.apache.beam.sdk.values.WindowingStrategy;
+// import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.Iterables;
+// import org.apache.flink.api.java.functions.KeySelector;
+// import org.apache.flink.api.java.typeutils.GenericTypeInfo;
+// import org.apache.flink.runtime.checkpoint.OperatorSubtaskState;
+// import org.apache.flink.streaming.runtime.streamrecord.StreamRecord;
+// import org.apache.flink.streaming.util.KeyedOneInputStreamOperatorTestHarness;
+// import org.joda.time.Duration;
+// import org.joda.time.Instant;
+// import org.junit.Test;
+// import org.junit.runner.RunWith;
+// import org.junit.runners.JUnit4;
+//
+/// ** Tests for {@link WindowDoFnOperator}. */
+// @RunWith(JUnit4.class)
+// @SuppressWarnings({
 //  "rawtypes", // TODO(https://github.com/apache/beam/issues/20447)
-//})
-//public class WindowDoFnOperatorTest {
+// })
+// public class WindowDoFnOperatorTest {
 //
 //  @Test
 //  public void testRestore() throws Exception {
@@ -129,7 +131,8 @@
 //        testHarness = createTestHarness(windowDoFnOperator);
 //    testHarness.open();
 //
-//    DoFnOperator<KV<Long, Long>, KeyedWorkItem<Long, Long>, KV<Long, Long>>.FlinkTimerInternals timerInternals =
+//    DoFnOperator<KV<Long, Long>, KeyedWorkItem<Long, Long>, KV<Long, Long>>.FlinkTimerInternals
+// timerInternals =
 //        windowDoFnOperator.timerInternals;
 //
 //    // process elements
@@ -184,7 +187,8 @@
 //        stripStreamRecordFromWindowedValue(testHarness.getOutput()),
 //        containsInAnyOrder(
 //            WindowedValue.of(
-//                KV.of(1L, 100L), new Instant(99), window, PaneInfo.createPane(true, true, ON_TIME)),
+//                KV.of(1L, 100L), new Instant(99), window, PaneInfo.createPane(true, true,
+// ON_TIME)),
 //            WindowedValue.of(
 //                KV.of(2L, 150L),
 //                new Instant(199),
@@ -238,7 +242,8 @@
 //
 //  private KeyedOneInputStreamOperatorTestHarness<
 //          ByteBuffer, WindowedValue<KeyedWorkItem<Long, Long>>, WindowedValue<KV<Long, Long>>>
-//      createTestHarness(WindowDoFnOperator<Long, Long, Long> windowDoFnOperator) throws Exception {
+//      createTestHarness(WindowDoFnOperator<Long, Long, Long> windowDoFnOperator) throws Exception
+// {
 //    return new KeyedOneInputStreamOperatorTestHarness<>(
 //        windowDoFnOperator,
 //        (KeySelector<WindowedValue<KeyedWorkItem<Long, Long>>, ByteBuffer>)
@@ -263,7 +268,8 @@
 //    private IntervalWindow window;
 //
 //    StreamRecord<WindowedValue<KeyedWorkItem<Long, Long>>> toStreamRecord() {
-//      WindowedValue<Long> item = WindowedValue.of(value, new Instant(timestamp), window, NO_FIRING);
+//      WindowedValue<Long> item = WindowedValue.of(value, new Instant(timestamp), window,
+// NO_FIRING);
 //      WindowedValue<KeyedWorkItem<Long, Long>> keyedItem =
 //          WindowedValue.of(
 //              new SingletonKeyedWorkItem<>(key, item), new Instant(timestamp), window, NO_FIRING);
@@ -307,4 +313,4 @@
 //      }
 //    }
 //  }
-//}
+// }

From 37847e7d049ba6d94f9aa349ff8a4f663ebbbd47 Mon Sep 17 00:00:00 2001
From: jto <boudhevil@gmail.com>
Date: Fri, 9 Aug 2024 10:11:44 +0200
Subject: [PATCH 10/26] [Flink] Combine before Reduce (no side-input only)

[Flink] Implement partial reduce

[Flink] dead code cleanup

[Flink] spotless

[Flink] persistent PartialReduceBundleOperator operator state
---
 .../flink/FlinkExecutionEnvironments.java     |   9 +-
 .../FlinkStreamingTransformTranslators.java   | 397 ++++++++----------
 .../wrappers/streaming/DoFnOperator.java      |   8 +-
 .../PartialReduceBundleOperator.java          | 175 ++++++++
 .../streaming/state/FlinkStateInternals.java  |  17 +-
 5 files changed, 371 insertions(+), 235 deletions(-)
 create mode 100644 runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/PartialReduceBundleOperator.java

diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkExecutionEnvironments.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkExecutionEnvironments.java
index 1ef5da6c124d..014b1f95fc92 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkExecutionEnvironments.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkExecutionEnvironments.java
@@ -237,12 +237,15 @@ public static StreamExecutionEnvironment createStreamExecutionEnvironment(
     flinkStreamEnv.setParallelism(parallelism);
     if (options.getMaxParallelism() > 0) {
       flinkStreamEnv.setMaxParallelism(options.getMaxParallelism());
-    } else if(!options.isStreaming()) {
+    } else if (!options.isStreaming()) {
       // In Flink maxParallelism defines the number of keyGroups.
-      // (see https://github.com/apache/flink/blob/e9dd4683f758b463d0b5ee18e49cecef6a70c5cf/flink-runtime/src/main/java/org/apache/flink/runtime/state/KeyGroupRangeAssignment.java#L76)
+      // (see
+      // https://github.com/apache/flink/blob/e9dd4683f758b463d0b5ee18e49cecef6a70c5cf/flink-runtime/src/main/java/org/apache/flink/runtime/state/KeyGroupRangeAssignment.java#L76)
       // The default value (parallelism * 1.5)
-      // (see https://github.com/apache/flink/blob/e9dd4683f758b463d0b5ee18e49cecef6a70c5cf/flink-runtime/src/main/java/org/apache/flink/runtime/state/KeyGroupRangeAssignment.java#L137-L147)
+      // (see
+      // https://github.com/apache/flink/blob/e9dd4683f758b463d0b5ee18e49cecef6a70c5cf/flink-runtime/src/main/java/org/apache/flink/runtime/state/KeyGroupRangeAssignment.java#L137-L147)
       // create a lot of skew so we force maxParallelism = parallelism in Batch mode.
+      LOG.info("Setting maxParallelism to {}", parallelism);
       flinkStreamEnv.setMaxParallelism(parallelism);
     }
     // set parallelism in the options (required by some execution code)
diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingTransformTranslators.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingTransformTranslators.java
index a70ca2291894..9ba19722cfd3 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingTransformTranslators.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingTransformTranslators.java
@@ -39,6 +39,8 @@
 import org.apache.beam.runners.flink.translation.types.CoderTypeInformation;
 import org.apache.beam.runners.flink.translation.wrappers.streaming.DoFnOperator;
 import org.apache.beam.runners.flink.translation.wrappers.streaming.KvToByteBufferKeySelector;
+import org.apache.beam.runners.flink.translation.wrappers.streaming.PartialReduceBundleOperator;
+import org.apache.beam.runners.flink.translation.wrappers.streaming.ProcessingTimeCallbackCompat;
 import org.apache.beam.runners.flink.translation.wrappers.streaming.SingletonKeyedWorkItem;
 import org.apache.beam.runners.flink.translation.wrappers.streaming.SingletonKeyedWorkItemCoder;
 import org.apache.beam.runners.flink.translation.wrappers.streaming.SplittableDoFnOperator;
@@ -52,8 +54,10 @@
 import org.apache.beam.runners.flink.translation.wrappers.streaming.io.source.bounded.FlinkBoundedSource;
 import org.apache.beam.runners.flink.translation.wrappers.streaming.io.source.unbounded.FlinkUnboundedSource;
 import org.apache.beam.sdk.coders.ByteArrayCoder;
+import org.apache.beam.sdk.coders.CannotProvideCoderException;
 import org.apache.beam.sdk.coders.Coder;
 import org.apache.beam.sdk.coders.CoderException;
+import org.apache.beam.sdk.coders.CoderRegistry;
 import org.apache.beam.sdk.coders.IterableCoder;
 import org.apache.beam.sdk.coders.KvCoder;
 import org.apache.beam.sdk.coders.VoidCoder;
@@ -65,6 +69,7 @@
 import org.apache.beam.sdk.testing.TestStream;
 import org.apache.beam.sdk.transforms.Combine;
 import org.apache.beam.sdk.transforms.CombineFnBase.GlobalCombineFn;
+import org.apache.beam.sdk.transforms.CombineWithContext;
 import org.apache.beam.sdk.transforms.DoFn;
 import org.apache.beam.sdk.transforms.DoFnSchemaInformation;
 import org.apache.beam.sdk.transforms.Impulse;
@@ -96,6 +101,7 @@
 import org.apache.beam.sdk.values.ValueWithRecordId;
 import org.apache.beam.sdk.values.WindowingStrategy;
 import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.annotations.VisibleForTesting;
+import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.ImmutableList;
 import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.ImmutableMap;
 import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.Maps;
 import org.apache.flink.api.common.eventtime.WatermarkStrategy;
@@ -946,11 +952,6 @@ public void translateNode(
 
       DataStream<WindowedValue<KV<K, InputT>>> inputDataStream = context.getInputDataStream(input);
 
-//      WindowedValue.FullWindowedValueCoder<KV<K, byte[]>> windowedBinaryKVCoder =
-//          WindowedValue.getFullCoder(
-//              KvCoder.of(inputKvCoder.getKeyCoder(), ByteArrayCoder.of()),
-//              input.getWindowingStrategy().getWindowFn().windowCoder());
-
       WindowedValue.FullWindowedValueCoder<KeyedWorkItem<K, InputT>> windowedKeyedWorkItemCoder =
           WindowedValue.getFullCoder(
               KeyedWorkItemCoder.of(
@@ -959,29 +960,21 @@ public void translateNode(
                   input.getWindowingStrategy().getWindowFn().windowCoder()),
               input.getWindowingStrategy().getWindowFn().windowCoder());
 
-//      CoderTypeInformation<WindowedValue<KV<K, byte[]>>> binaryKVTypeInfo =
-//          new CoderTypeInformation<>(windowedBinaryKVCoder, context.getPipelineOptions());
-
-//      DataStream<WindowedValue<KV<K, byte[]>>> inputBinaryDataStream =
-//          inputDataStream
-//              .flatMap(new ToBinaryKV<>(context.getPipelineOptions(), inputKvCoder.getValueCoder()))
-//              .returns(binaryKVTypeInfo)
-//              .name("ToBinaryKV");
-
       KvToByteBufferKeySelector<K, InputT> keySelector =
           new KvToByteBufferKeySelector<>(
               inputKvCoder.getKeyCoder(),
               new SerializablePipelineOptions(context.getPipelineOptions()));
 
       KeyedStream<WindowedValue<KV<K, InputT>>, ByteBuffer> keyedWorkItemStream =
-              inputDataStream.keyBy(keySelector);
+          inputDataStream.keyBy(keySelector);
 
       SystemReduceFn<K, InputT, Iterable<InputT>, Iterable<InputT>, BoundedWindow> reduceFn =
           SystemReduceFn.buffering(inputKvCoder.getValueCoder());
 
       Coder<WindowedValue<KV<K, Iterable<InputT>>>> outputCoder =
           WindowedValue.getFullCoder(
-              KvCoder.of(inputKvCoder.getKeyCoder(), IterableCoder.of(inputKvCoder.getValueCoder())),
+              KvCoder.of(
+                  inputKvCoder.getKeyCoder(), IterableCoder.of(inputKvCoder.getValueCoder())),
               windowingStrategy.getWindowFn().windowCoder());
 
       TypeInformation<WindowedValue<KV<K, Iterable<InputT>>>> outputTypeInfo =
@@ -1014,14 +1007,7 @@ public void translateNode(
               workItemKeySelector);
 
       final SingleOutputStreamOperator<WindowedValue<KV<K, Iterable<InputT>>>> outDataStream =
-          keyedWorkItemStream
-              .transform(fullName, outputTypeInfo, doFnOperator)
-              .uid(fullName);
-//              .flatMap(
-//                  new ToGroupByKeyResult<>(
-//                      context.getPipelineOptions(), inputKvCoder.getValueCoder()))
-//              .returns(context.getTypeInfo(context.getOutput(transform)))
-//              .name("ToGBKResult");
+          keyedWorkItemStream.transform(fullName, outputTypeInfo, doFnOperator).uid(fullName);
 
       context.setOutputDataStream(context.getOutput(transform), outDataStream);
     }
@@ -1048,129 +1034,94 @@ boolean canTranslate(
           || ((Combine.PerKey) transform).getSideInputs().isEmpty();
     }
 
-    /*
-        private GlobalCombineFn<? super InputT, ?, ?> toPartialFlinkCombineFn(GlobalCombineFn<? super InputT, ?, OutputT> combineFn) {
-
-          if(combineFn instanceof Combine.CombineFn) {
-            return new Combine.CombineFn<InputT, Object, Object>() {
-
-              Combine.CombineFn<? super InputT, Object, OutputT> fn =
-                  (Combine.CombineFn<? super InputT, Object, OutputT>) combineFn;
-
-              @Override
-              public Object createAccumulator() {
-                return fn.createAccumulator();
-              }
-
-              @Override
-              public Object addInput(Object mutableAccumulator, InputT input) {
-                return fn.addInput(mutableAccumulator, input);
-              }
-
-              @Override
-              public Object mergeAccumulators(Iterable<Object> accumulators) {
-                return fn.mergeAccumulators(accumulators);
-              }
-
-              @Override
-              public Object extractOutput(Object accumulator) {
-                return accumulator;
-              }
-            };
-          } else if (combineFn instanceof CombineWithContext.CombineFnWithContext){
-            return new CombineWithContext.CombineFnWithContext<InputT, Object, Object>() {
-              CombineWithContext.CombineFnWithContext<? super InputT, Object, OutputT> fn =
-                  (CombineWithContext.CombineFnWithContext<? super InputT, Object, OutputT>) combineFn;
-              @Override
-              public Object createAccumulator(CombineWithContext.Context c) {
-                return fn.createAccumulator(c);
-              }
-
-              @Override
-              public Object addInput(Object accumulator, InputT input, CombineWithContext.Context c) {
-                return fn.addInput(accumulator, input, c);
-              }
-
-              @Override
-              public Object mergeAccumulators(Iterable<Object> accumulators, CombineWithContext.Context c) {
-                return fn.mergeAccumulators(accumulators, c);
-              }
-
-              @Override
-              public Object extractOutput(Object accumulator, CombineWithContext.Context c) {
-                return accumulator;
-              }
-            };
+    private static <InputT, OutputT> GlobalCombineFn<Object, Object, OutputT> toFinalFlinkCombineFn(
+        GlobalCombineFn<? super InputT, ?, OutputT> combineFn, Coder<InputT> inputTCoder) {
+
+      if (combineFn instanceof Combine.CombineFn) {
+        return new Combine.CombineFn<Object, Object, OutputT>() {
+
+          @SuppressWarnings("unchecked")
+          final Combine.CombineFn<InputT, Object, OutputT> fn =
+              (Combine.CombineFn<InputT, Object, OutputT>) combineFn;
+
+          @Override
+          public Object createAccumulator() {
+            return fn.createAccumulator();
           }
 
-          throw new IllegalArgumentException("Unsupported CombineFn implementation: " + combineFn.getClass());
-        }
+          @Override
+          public Coder<Object> getAccumulatorCoder(CoderRegistry registry, Coder<Object> inputCoder)
+              throws CannotProvideCoderException {
+            return fn.getAccumulatorCoder(registry, inputTCoder);
+          }
 
-        private GlobalCombineFn<?, ?, OutputT> toFinalFlinkCombineFn(GlobalCombineFn<? super InputT, ?, OutputT> combineFn) {
-
-          if(combineFn instanceof Combine.CombineFn) {
-            return new Combine.CombineFn<Object, Object, OutputT>() {
-              Combine.CombineFn<? super InputT, Object, OutputT> fn =
-                  (Combine.CombineFn<? super InputT, Object, OutputT>) combineFn;
-              @Override
-              public Object createAccumulator() {
-                return fn.createAccumulator();
-              }
-
-              @Override
-              public Object addInput(Object mutableAccumulator, Object input) {
-                return fn.mergeAccumulators(ImmutableList.of(mutableAccumulator, input));
-              }
-
-              @Override
-              public Object mergeAccumulators(Iterable<Object> accumulators) {
-                return fn.mergeAccumulators(accumulators);
-              }
-
-              @Override
-              public OutputT extractOutput(Object accumulator) {
-                return fn.extractOutput(accumulator);
-              }
-            };
-          } else if (combineFn instanceof CombineWithContext.CombineFnWithContext){
-            return new CombineWithContext.CombineFnWithContext<Object, Object, OutputT>() {
-              CombineWithContext.CombineFnWithContext<? super InputT, Object, OutputT> fn =
-                  (CombineWithContext.CombineFnWithContext<? super InputT, Object, OutputT>) combineFn;
-              @Override
-              public Object createAccumulator(CombineWithContext.Context c) {
-                return fn.createAccumulator(c);
-              }
-
-              @Override
-              public Object addInput(Object accumulator, Object input, CombineWithContext.Context c) {
-                return fn.mergeAccumulators(ImmutableList.of(accumulator, input), c);
-              }
-
-              @Override
-              public Object mergeAccumulators(Iterable<Object> accumulators, CombineWithContext.Context c) {
-                return fn.mergeAccumulators(accumulators, c);
-              }
-
-              @Override
-              public OutputT extractOutput(Object accumulator, CombineWithContext.Context c) {
-                return fn.extractOutput(accumulator, c);
-              }
-            };
+          @Override
+          public Object addInput(Object mutableAccumulator, Object input) {
+            return fn.mergeAccumulators(ImmutableList.of(mutableAccumulator, input));
           }
-          throw new IllegalArgumentException("Unsupported CombineFn implementation: " + combineFn.getClass());
-        }
-    */
 
-    private WindowDoFnOperator<K, InputT, OutputT> getDoFnOperator(
-        FlinkStreamingTranslationContext context,
-        PTransform<PCollection<KV<K, InputT>>, PCollection<KV<K, OutputT>>> transform,
-        GlobalCombineFn<? super InputT, ?, OutputT> combineFn,
-        Map<Integer, PCollectionView<?>> sideInputTagMapping,
-        List<PCollectionView<?>> sideInputs) {
+          @Override
+          public Object mergeAccumulators(Iterable<Object> accumulators) {
+            return fn.mergeAccumulators(accumulators);
+          }
+
+          @Override
+          public OutputT extractOutput(Object accumulator) {
+            return fn.extractOutput(accumulator);
+          }
+        };
+      } else if (combineFn instanceof CombineWithContext.CombineFnWithContext) {
+        return new CombineWithContext.CombineFnWithContext<Object, Object, OutputT>() {
+
+          @SuppressWarnings("unchecked")
+          final CombineWithContext.CombineFnWithContext<InputT, Object, OutputT> fn =
+              (CombineWithContext.CombineFnWithContext<InputT, Object, OutputT>) combineFn;
+
+          @Override
+          public Object createAccumulator(CombineWithContext.Context c) {
+            return fn.createAccumulator(c);
+          }
+
+          @Override
+          public Coder<Object> getAccumulatorCoder(CoderRegistry registry, Coder<Object> inputCoder)
+              throws CannotProvideCoderException {
+            return fn.getAccumulatorCoder(registry, inputTCoder);
+          }
+
+          @Override
+          public Object addInput(Object accumulator, Object input, CombineWithContext.Context c) {
+            return fn.mergeAccumulators(ImmutableList.of(accumulator, input), c);
+          }
+
+          @Override
+          public Object mergeAccumulators(
+              Iterable<Object> accumulators, CombineWithContext.Context c) {
+            return fn.mergeAccumulators(accumulators, c);
+          }
+
+          @Override
+          public OutputT extractOutput(Object accumulator, CombineWithContext.Context c) {
+            return fn.extractOutput(accumulator, c);
+          }
+        };
+      }
+      throw new IllegalArgumentException(
+          "Unsupported CombineFn implementation: " + combineFn.getClass());
+    }
+
+    private static <K, InputC, OutputC, InputT, OutputT>
+        WindowDoFnOperator<K, InputC, OutputC> getDoFnOperator(
+            FlinkStreamingTranslationContext context,
+            PTransform<PCollection<KV<K, InputT>>, PCollection<KV<K, OutputT>>> transform,
+            KvCoder<K, InputC> inputKvCoder,
+            Coder<WindowedValue<KV<K, OutputC>>> outputCoder,
+            GlobalCombineFn<? super InputC, ?, OutputC> combineFn,
+            Map<Integer, PCollectionView<?>> sideInputTagMapping,
+            List<PCollectionView<?>> sideInputs) {
 
       // Naming
       String fullName = getCurrentTransformName(context);
-      TupleTag<KV<K, OutputT>> mainTag = new TupleTag<>("main output");
+      TupleTag<KV<K, OutputC>> mainTag = new TupleTag<>("main output");
 
       // input infos
       PCollection<KV<K, InputT>> input = context.getInput(transform);
@@ -1181,31 +1132,26 @@ private WindowDoFnOperator<K, InputT, OutputT> getDoFnOperator(
           new SerializablePipelineOptions(context.getPipelineOptions());
 
       // Coders
-      KvCoder<K, InputT> inputKvCoder = (KvCoder<K, InputT>) input.getCoder();
       Coder<K> keyCoder = inputKvCoder.getKeyCoder();
 
-      SingletonKeyedWorkItemCoder<K, InputT> workItemCoder =
+      SingletonKeyedWorkItemCoder<K, InputC> workItemCoder =
           SingletonKeyedWorkItemCoder.of(
               keyCoder,
               inputKvCoder.getValueCoder(),
-              input.getWindowingStrategy().getWindowFn().windowCoder());
-
-      WindowedValue.FullWindowedValueCoder<KeyedWorkItem<K, InputT>> windowedWorkItemCoder =
-          WindowedValue.getFullCoder(
-              workItemCoder, input.getWindowingStrategy().getWindowFn().windowCoder());
+              windowingStrategy.getWindowFn().windowCoder());
 
-      Coder<WindowedValue<KV<K, OutputT>>> outputCoder =
-          context.getWindowedInputCoder(context.getOutput(transform));
+      WindowedValue.FullWindowedValueCoder<KeyedWorkItem<K, InputC>> windowedWorkItemCoder =
+          WindowedValue.getFullCoder(workItemCoder, windowingStrategy.getWindowFn().windowCoder());
 
       // Combining fn
-      SystemReduceFn<K, InputT, ?, OutputT, BoundedWindow> reduceFn =
+      SystemReduceFn<K, InputC, ?, OutputC, BoundedWindow> reduceFn =
           SystemReduceFn.combining(
               keyCoder,
               AppliedCombineFn.withInputCoder(
                   combineFn, input.getPipeline().getCoderRegistry(), inputKvCoder));
 
       // Key selector
-      WorkItemKeySelector<K, InputT> workItemKeySelector =
+      WorkItemKeySelector<K, InputC> workItemKeySelector =
           new WorkItemKeySelector<>(keyCoder, serializablePipelineOptions);
 
       return new WindowDoFnOperator<>(
@@ -1234,17 +1180,21 @@ public void translateNode(
 
       KvCoder<K, InputT> inputKvCoder = (KvCoder<K, InputT>) input.getCoder();
       Coder<K> keyCoder = inputKvCoder.getKeyCoder();
+      Coder<WindowedValue<KV<K, OutputT>>> outputCoder =
+          context.getWindowedInputCoder(context.getOutput(transform));
 
       DataStream<WindowedValue<KV<K, InputT>>> inputDataStream = context.getInputDataStream(input);
 
       SerializablePipelineOptions serializablePipelineOptions =
           new SerializablePipelineOptions(context.getPipelineOptions());
 
-      GlobalCombineFn<? super InputT, ?, OutputT> combineFn = ((Combine.PerKey) transform).getFn();
+      @SuppressWarnings("unchecked")
+      GlobalCombineFn<InputT, ?, OutputT> combineFn = ((Combine.PerKey) transform).getFn();
 
       TypeInformation<WindowedValue<KV<K, OutputT>>> outputTypeInfo =
           context.getTypeInfo(context.getOutput(transform));
 
+      @SuppressWarnings("unchecked")
       List<PCollectionView<?>> sideInputs = ((Combine.PerKey) transform).getSideInputs();
 
       KeyedStream<WindowedValue<KV<K, InputT>>, ByteBuffer> keyedStream =
@@ -1252,12 +1202,79 @@ public void translateNode(
               new KvToByteBufferKeySelector<>(keyCoder, serializablePipelineOptions));
 
       if (sideInputs.isEmpty()) {
-        WindowDoFnOperator<K, InputT, OutputT> doFnOperator =
-            getDoFnOperator(
-                context, transform, combineFn, new HashMap<>(), Collections.emptyList());
+        SingleOutputStreamOperator<WindowedValue<KV<K, OutputT>>> outDataStream;
+
+        if (!context.isStreaming()) {
+          Coder<WindowedValue<KV<K, Object>>> windowedAccumCoder;
+          KvCoder<K, Object> accumKvCoder;
+          try {
+            @SuppressWarnings("unchecked")
+            Coder<Object> accumulatorCoder =
+                (Coder<Object>)
+                    combineFn.getAccumulatorCoder(
+                        input.getPipeline().getCoderRegistry(), inputKvCoder.getValueCoder());
+
+            accumKvCoder = KvCoder.of(inputKvCoder.getKeyCoder(), accumulatorCoder);
+
+            windowedAccumCoder =
+                WindowedValue.getFullCoder(
+                    accumKvCoder, input.getWindowingStrategy().getWindowFn().windowCoder());
+          } catch (CannotProvideCoderException e) {
+            throw new RuntimeException(e);
+          }
 
-        SingleOutputStreamOperator<WindowedValue<KV<K, OutputT>>> outDataStream =
-            keyedStream.transform(fullName, outputTypeInfo, doFnOperator).uid(fullName);
+          TupleTag<KV<K, Object>> mainTag = new TupleTag<>("main output");
+
+          PartialReduceBundleOperator<K, InputT, OutputT, Object> partialDoFnOperator =
+              new PartialReduceBundleOperator<>(
+                  (GlobalCombineFn<InputT, Object, OutputT>) combineFn,
+                  getCurrentTransformName(context),
+                  context.getWindowedInputCoder(input),
+                  mainTag,
+                  Collections.emptyList(),
+                  new DoFnOperator.MultiOutputOutputManagerFactory<>(
+                      mainTag, windowedAccumCoder, serializablePipelineOptions),
+                  input.getWindowingStrategy(),
+                  new HashMap<>(),
+                  Collections.emptyList(),
+                  context.getPipelineOptions());
+
+          // final aggregation from AccumT to OutputT
+          WindowDoFnOperator<K, Object, OutputT> finalDoFnOperator =
+              getDoFnOperator(
+                  context,
+                  transform,
+                  accumKvCoder,
+                  outputCoder,
+                  toFinalFlinkCombineFn(combineFn, inputKvCoder.getValueCoder()),
+                  new HashMap<>(),
+                  Collections.emptyList());
+
+          String partialName = "Combine: " + fullName;
+          CoderTypeInformation<WindowedValue<KV<K, Object>>> partialTypeInfo =
+              new CoderTypeInformation<>(windowedAccumCoder, context.getPipelineOptions());
+
+          outDataStream =
+              inputDataStream
+                  .transform(partialName, partialTypeInfo, partialDoFnOperator)
+                  .uid(partialName)
+                  .keyBy(new KvToByteBufferKeySelector<>(keyCoder, serializablePipelineOptions))
+                  .transform(fullName, outputTypeInfo, finalDoFnOperator)
+                  .uid(fullName);
+        } else {
+          WindowDoFnOperator<K, InputT, OutputT> doFnOperator =
+              getDoFnOperator(
+                  context,
+                  transform,
+                  inputKvCoder,
+                  outputCoder,
+                  combineFn,
+                  new HashMap<>(),
+                  Collections.emptyList());
+
+          outDataStream =
+              keyedStream.transform(fullName, outputTypeInfo, doFnOperator).uid(fullName);
+        }
 
         context.setOutputDataStream(context.getOutput(transform), outDataStream);
       } else {
@@ -1265,7 +1282,14 @@ public void translateNode(
             transformSideInputs(sideInputs, context);
 
         WindowDoFnOperator<K, InputT, OutputT> doFnOperator =
-            getDoFnOperator(context, transform, combineFn, transformSideInputs.f0, sideInputs);
+            getDoFnOperator(
+                context,
+                transform,
+                inputKvCoder,
+                outputCoder,
+                combineFn,
+                transformSideInputs.f0,
+                sideInputs);
 
         // we have to manually contruct the two-input transform because we're not
         // allowed to have only one input keyed, normally.
@@ -1455,65 +1479,6 @@ public void flatMap(T t, Collector<T> collector) throws Exception {
     }
   }
 
-  static class ToBinaryKV<K, InputT>
-      extends RichFlatMapFunction<WindowedValue<KV<K, InputT>>, WindowedValue<KV<K, byte[]>>> {
-
-    private final SerializablePipelineOptions options;
-    private final Coder<InputT> valueCoder;
-
-    ToBinaryKV(PipelineOptions options, Coder<InputT> valueCoder) {
-      this.options = new SerializablePipelineOptions(options);
-      this.valueCoder = valueCoder;
-    }
-
-    @Override
-    public void open(Configuration parameters) {
-      // Initialize FileSystems for any coders which may want to use the FileSystem,
-      // see https://issues.apache.org/jira/browse/BEAM-8303
-      FileSystems.setDefaultPipelineOptions(options.get());
-    }
-
-    @Override
-    public void flatMap(
-        WindowedValue<KV<K, InputT>> in, Collector<WindowedValue<KV<K, byte[]>>> out)
-        throws CoderException {
-      final byte[] binaryValue = CoderUtils.encodeToByteArray(valueCoder, in.getValue().getValue());
-      out.collect(in.withValue(KV.of(in.getValue().getKey(), binaryValue)));
-    }
-  }
-
-  static class ToGroupByKeyResult<KeyT, ValueT>
-      extends RichFlatMapFunction<
-          WindowedValue<KV<KeyT, Iterable<byte[]>>>, WindowedValue<KV<KeyT, Iterable<ValueT>>>> {
-
-    private final SerializablePipelineOptions options;
-    private final Coder<ValueT> valueCoder;
-
-    ToGroupByKeyResult(PipelineOptions options, Coder<ValueT> valueCoder) {
-      this.options = new SerializablePipelineOptions(options);
-      this.valueCoder = valueCoder;
-    }
-
-    @Override
-    public void open(Configuration parameters) {
-      // Initialize FileSystems for any coders which may want to use the FileSystem,
-      // see https://issues.apache.org/jira/browse/BEAM-8303
-      FileSystems.setDefaultPipelineOptions(options.get());
-    }
-
-    @Override
-    public void flatMap(
-        WindowedValue<KV<KeyT, Iterable<byte[]>>> element,
-        Collector<WindowedValue<KV<KeyT, Iterable<ValueT>>>> collector)
-        throws CoderException {
-      final List<ValueT> result = new ArrayList<>();
-      for (byte[] binaryValue : element.getValue().getValue()) {
-        result.add(CoderUtils.decodeFromByteArray(valueCoder, binaryValue));
-      }
-      collector.collect(element.withValue(KV.of(element.getValue().getKey(), result)));
-    }
-  }
-
   /** Registers classes specialized to the Flink runner. */
   @AutoService(TransformPayloadTranslatorRegistrar.class)
   public static class FlinkTransformsRegistrar implements TransformPayloadTranslatorRegistrar {
diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/DoFnOperator.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/DoFnOperator.java
index 772673a91da7..db6eba270d1f 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/DoFnOperator.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/DoFnOperator.java
@@ -271,7 +271,7 @@ public class DoFnOperator<PreInputT, InputT, OutputT> extends AbstractStreamOper
 
   /** Constructor for DoFnOperator. */
   public DoFnOperator(
-      DoFn<InputT, OutputT> doFn,
+      @Nullable DoFn<InputT, OutputT> doFn,
       String stepName,
       Coder<WindowedValue<InputT>> inputWindowedCoder,
       Map<TupleTag<?>, Coder<?>> outputCoders,
@@ -282,8 +282,8 @@ public DoFnOperator(
       Map<Integer, PCollectionView<?>> sideInputTagMapping,
       Collection<PCollectionView<?>> sideInputs,
       PipelineOptions options,
-      Coder<?> keyCoder,
-      KeySelector<WindowedValue<InputT>, ?> keySelector,
+      @Nullable Coder<?> keyCoder,
+      @Nullable KeySelector<WindowedValue<InputT>, ?> keySelector,
       DoFnSchemaInformation doFnSchemaInformation,
       Map<String, PCollectionView<?>> sideInputMapping) {
     this.doFn = doFn;
@@ -1055,7 +1055,7 @@ public void prepareSnapshotPreBarrier(long checkpointId) {
   }
 
   @Override
-  public final void snapshotState(StateSnapshotContext context) throws Exception {
+  public void snapshotState(StateSnapshotContext context) throws Exception {
     if (checkpointStats != null) {
       checkpointStats.snapshotStart(context.getCheckpointId());
     }
diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/PartialReduceBundleOperator.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/PartialReduceBundleOperator.java
new file mode 100644
index 000000000000..b81d19889622
--- /dev/null
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/PartialReduceBundleOperator.java
@@ -0,0 +1,175 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.beam.runners.flink.translation.wrappers.streaming;
+
+import java.util.*;
+import java.util.stream.Collectors;
+
+import org.apache.beam.runners.flink.translation.functions.AbstractFlinkCombineRunner;
+import org.apache.beam.runners.flink.translation.functions.HashingFlinkCombineRunner;
+import org.apache.beam.runners.flink.translation.functions.SortingFlinkCombineRunner;
+import org.apache.beam.runners.flink.translation.types.CoderTypeSerializer;
+import org.apache.beam.sdk.coders.Coder;
+import org.apache.beam.sdk.options.PipelineOptions;
+import org.apache.beam.sdk.transforms.CombineFnBase;
+import org.apache.beam.sdk.transforms.DoFn;
+import org.apache.beam.sdk.transforms.DoFnSchemaInformation;
+import org.apache.beam.sdk.transforms.windowing.BoundedWindow;
+import org.apache.beam.sdk.transforms.windowing.Sessions;
+import org.apache.beam.sdk.util.WindowedValue;
+import org.apache.beam.sdk.values.KV;
+import org.apache.beam.sdk.values.PCollectionView;
+import org.apache.beam.sdk.values.TupleTag;
+import org.apache.beam.sdk.values.WindowingStrategy;
+import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.ArrayListMultimap;
+import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.ImmutableList;
+import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.Multimap;
+import org.apache.flink.api.common.state.ListState;
+import org.apache.flink.api.common.state.ListStateDescriptor;
+import org.apache.flink.runtime.state.StateInitializationContext;
+import org.apache.flink.runtime.state.StateSnapshotContext;
+import org.apache.flink.util.Collector;
+import org.checkerframework.checker.nullness.qual.Nullable;
+
+public class PartialReduceBundleOperator<K, InputT, OutputT, AccumT>
+    extends DoFnOperator<KV<K, InputT>, KV<K, InputT>, KV<K, AccumT>> {
+
+  private final CombineFnBase.GlobalCombineFn<InputT, AccumT, OutputT> combineFn;
+
+  private Multimap<K, WindowedValue<KV<K, InputT>>> state;
+  private transient @Nullable ListState<WindowedValue<KV<K, InputT>>> checkpointedState;
+
+  public PartialReduceBundleOperator(
+      CombineFnBase.GlobalCombineFn<InputT, AccumT, OutputT> combineFn,
+      String stepName,
+      Coder<WindowedValue<KV<K, InputT>>> windowedInputCoder,
+      TupleTag<KV<K, AccumT>> mainOutputTag,
+      List<TupleTag<?>> additionalOutputTags,
+      OutputManagerFactory<KV<K, AccumT>> outputManagerFactory,
+      WindowingStrategy<?, ?> windowingStrategy,
+      Map<Integer, PCollectionView<?>> sideInputTagMapping,
+      Collection<PCollectionView<?>> sideInputs,
+      PipelineOptions options) {
+    super(
+        null,
+        stepName,
+        windowedInputCoder,
+        Collections.emptyMap(),
+        mainOutputTag,
+        additionalOutputTags,
+        outputManagerFactory,
+        windowingStrategy,
+        sideInputTagMapping,
+        sideInputs,
+        options,
+        null,
+        null,
+        DoFnSchemaInformation.create(),
+        Collections.emptyMap());
+
+    this.combineFn = combineFn;
+    this.state = ArrayListMultimap.create();
+    this.checkpointedState = null;
+  }
+
+  @Override
+  public void open() throws Exception {
+    clearState();
+    setBundleFinishedCallback(this::finishBundle);
+    super.open();
+  }
+
+  private void finishBundle() {
+    AbstractFlinkCombineRunner<K, InputT, AccumT, AccumT, BoundedWindow> reduceRunner;
+    try {
+      if (windowingStrategy.needsMerge() && windowingStrategy.getWindowFn() instanceof Sessions) {
+        reduceRunner = new SortingFlinkCombineRunner<>();
+      } else {
+        reduceRunner = new HashingFlinkCombineRunner<>();
+      }
+
+      for (Map.Entry<K, Collection<WindowedValue<KV<K, InputT>>>> e : state.asMap().entrySet()) {
+        //noinspection unchecked
+        reduceRunner.combine(
+            new AbstractFlinkCombineRunner.PartialFlinkCombiner<>(combineFn),
+            (WindowingStrategy<Object, BoundedWindow>) windowingStrategy,
+            sideInputReader,
+            serializedOptions.get(),
+            e.getValue(),
+            new Collector<WindowedValue<KV<K, AccumT>>>() {
+              @Override
+              public void collect(WindowedValue<KV<K, AccumT>> record) {
+                outputManager.output(mainOutputTag, record);
+              }
+
+              @Override
+              public void close() {}
+            });
+      }
+
+    } catch (Exception e) {
+      throw new RuntimeException(e);
+    }
+    clearState();
+  }
+
+  private void clearState() {
+    this.state = ArrayListMultimap.create();
+    if (this.checkpointedState != null) {
+      this.checkpointedState.clear();
+    }
+  }
+
+  @Override
+  public void initializeState(StateInitializationContext context) throws Exception {
+    super.initializeState(context);
+
+    ListStateDescriptor<WindowedValue<KV<K, InputT>>> descriptor =
+        new ListStateDescriptor<>(
+            "buffered-elements",
+            new CoderTypeSerializer<>(windowedInputCoder, serializedOptions));
+
+    checkpointedState = context.getOperatorStateStore().getListState(descriptor);
+
+    if(context.isRestored() && this.checkpointedState != null) {
+      for(WindowedValue<KV<K, InputT>> wkv : this.checkpointedState.get()) {
+        this.state.put(wkv.getValue().getKey(), wkv);
+      }
+    }
+  }
+
+  @Override
+  public void snapshotState(StateSnapshotContext context) throws Exception {
+    super.snapshotState(context);
+    if (this.checkpointedState != null) {
+      this.checkpointedState.update(new ArrayList<>(this.state.values()));
+    }
+  }
+
+  @Override
+  protected DoFn<KV<K, InputT>, KV<K, AccumT>> getDoFn() {
+    return new DoFn<KV<K, InputT>, KV<K, AccumT>>() {
+      @ProcessElement
+      public void processElement(ProcessContext c, BoundedWindow window) throws Exception {
+        WindowedValue<KV<K, InputT>> windowedValue =
+            WindowedValue.of(c.element(), c.timestamp(), window, c.pane());
+        state.put(Objects.requireNonNull(c.element()).getKey(), windowedValue);
+      }
+    };
+  }
+}
diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/state/FlinkStateInternals.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/state/FlinkStateInternals.java
index 8102582c4817..388271cdd68a 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/state/FlinkStateInternals.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/state/FlinkStateInternals.java
@@ -878,8 +878,7 @@ private static class FlinkCombiningState<K, InputT, AccumT, OutputT>
       this.namespaceSerializer = namespaceSerializer;
 
       flinkStateDescriptor =
-          new ValueStateDescriptor<>(
-              stateId, new CoderTypeSerializer<>(accumCoder, fasterCopy));
+          new ValueStateDescriptor<>(stateId, new CoderTypeSerializer<>(accumCoder, fasterCopy));
     }
 
     @Override
@@ -1047,8 +1046,7 @@ private static class FlinkCombiningStateWithContext<K, InputT, AccumT, OutputT>
       this.namespaceSerializer = namespaceSerializer;
 
       flinkStateDescriptor =
-          new ValueStateDescriptor<>(
-              stateId, new CoderTypeSerializer<>(accumCoder, fasterCopy));
+          new ValueStateDescriptor<>(stateId, new CoderTypeSerializer<>(accumCoder, fasterCopy));
     }
 
     @Override
@@ -1560,9 +1558,7 @@ private static class FlinkSetState<T> implements SetState<T> {
       this.flinkStateBackend = flinkStateBackend;
       this.flinkStateDescriptor =
           new MapStateDescriptor<>(
-              stateId,
-              new CoderTypeSerializer<>(coder, fasterCopy),
-              BooleanSerializer.INSTANCE);
+              stateId, new CoderTypeSerializer<>(coder, fasterCopy), BooleanSerializer.INSTANCE);
     }
 
     @Override
@@ -1765,9 +1761,7 @@ public <T> SetState<T> bindSet(String id, StateSpec<SetState<T>> spec, Coder<T>
         keyedStateBackend.getOrCreateKeyedState(
             namespaceSerializer,
             new MapStateDescriptor<>(
-                id,
-                new CoderTypeSerializer<>(elemCoder, fasterCopy),
-                BooleanSerializer.INSTANCE));
+                id, new CoderTypeSerializer<>(elemCoder, fasterCopy), BooleanSerializer.INSTANCE));
       } catch (Exception e) {
         throw new RuntimeException(e);
       }
@@ -1800,8 +1794,7 @@ public <T> OrderedListState<T> bindOrderedList(
         keyedStateBackend.getOrCreateKeyedState(
             namespaceSerializer,
             new ListStateDescriptor<>(
-                id,
-                new CoderTypeSerializer<>(TimestampedValueCoder.of(elemCoder), fasterCopy)));
+                id, new CoderTypeSerializer<>(TimestampedValueCoder.of(elemCoder), fasterCopy)));
       } catch (Exception e) {
         throw new RuntimeException(e);
       }

From 04f3d68771c00318f012c44b9df5cd4c0f122706 Mon Sep 17 00:00:00 2001
From: jto <boudhevil@gmail.com>
Date: Fri, 23 Aug 2024 16:24:28 +0200
Subject: [PATCH 11/26] [Flink] Combine before GBK

---
 .../types/CoderTypeSerializer.java            |   7 +-
 ...FlinkStreamingAggregationsTranslators.java | 286 ++++++++++
 .../FlinkStreamingTransformTranslators.java   | 498 +++++-------------
 3 files changed, 438 insertions(+), 353 deletions(-)
 create mode 100644 runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingAggregationsTranslators.java

diff --git a/runners/flink/1.17/src/main/java/org/apache/beam/runners/flink/translation/types/CoderTypeSerializer.java b/runners/flink/1.17/src/main/java/org/apache/beam/runners/flink/translation/types/CoderTypeSerializer.java
index 911dd3185adf..30dde7ace394 100644
--- a/runners/flink/1.17/src/main/java/org/apache/beam/runners/flink/translation/types/CoderTypeSerializer.java
+++ b/runners/flink/1.17/src/main/java/org/apache/beam/runners/flink/translation/types/CoderTypeSerializer.java
@@ -50,7 +50,12 @@ public class CoderTypeSerializer<T> extends TypeSerializer<T> {
   private final boolean fasterCopy;
 
   public CoderTypeSerializer(Coder<T> coder, SerializablePipelineOptions pipelineOptions) {
-    this(coder, Preconditions.checkNotNull(pipelineOptions).get().as(FlinkPipelineOptions.class).getFasterCopy());
+    this(
+        coder,
+        Preconditions.checkNotNull(pipelineOptions)
+            .get()
+            .as(FlinkPipelineOptions.class)
+            .getFasterCopy());
   }
 
   public CoderTypeSerializer(Coder<T> coder, boolean fasterCopy) {
diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingAggregationsTranslators.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingAggregationsTranslators.java
new file mode 100644
index 000000000000..60e0a1a8a058
--- /dev/null
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingAggregationsTranslators.java
@@ -0,0 +1,286 @@
+package org.apache.beam.runners.flink;
+
+import org.apache.beam.runners.core.KeyedWorkItem;
+import org.apache.beam.runners.core.SystemReduceFn;
+import org.apache.beam.runners.core.construction.SerializablePipelineOptions;
+import org.apache.beam.runners.flink.translation.types.CoderTypeInformation;
+import org.apache.beam.runners.flink.translation.wrappers.streaming.*;
+import org.apache.beam.sdk.coders.*;
+import org.apache.beam.sdk.transforms.Combine;
+import org.apache.beam.sdk.transforms.CombineFnBase;
+import org.apache.beam.sdk.transforms.CombineWithContext;
+import org.apache.beam.sdk.transforms.PTransform;
+import org.apache.beam.sdk.transforms.windowing.BoundedWindow;
+import org.apache.beam.sdk.util.AppliedCombineFn;
+import org.apache.beam.sdk.util.WindowedValue;
+import org.apache.beam.sdk.values.*;
+import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.ImmutableList;
+import org.apache.flink.api.common.typeinfo.TypeInformation;
+import org.apache.flink.streaming.api.datastream.DataStream;
+import org.apache.flink.streaming.api.datastream.SingleOutputStreamOperator;
+
+import java.util.*;
+
+public class FlinkStreamingAggregationsTranslators {
+  public static class ConcatenateAsIterable<T> extends Combine.CombineFn<T, List<T>, Iterable<T>> {
+    @Override
+    public List<T> createAccumulator() {
+      return new ArrayList<>();
+    }
+
+    @Override
+    public List<T> addInput(List<T> accumulator, T input) {
+      accumulator.add(input);
+      return accumulator;
+    }
+
+    @Override
+    public List<T> mergeAccumulators(Iterable<List<T>> accumulators) {
+      List<T> result = createAccumulator();
+      for (List<T> accumulator : accumulators) {
+        result.addAll(accumulator);
+      }
+      return result;
+    }
+
+    @Override
+    public List<T> extractOutput(List<T> accumulator) {
+      return accumulator;
+    }
+
+    @Override
+    public Coder<List<T>> getAccumulatorCoder(CoderRegistry registry, Coder<T> inputCoder) {
+      return ListCoder.of(inputCoder);
+    }
+
+    @Override
+    public Coder<Iterable<T>> getDefaultOutputCoder(CoderRegistry registry, Coder<T> inputCoder) {
+      return IterableCoder.of(inputCoder);
+    }
+  }
+
+  private static <InputT, OutputT> CombineFnBase.GlobalCombineFn<Object, Object, OutputT> toFinalFlinkCombineFn(
+      CombineFnBase.GlobalCombineFn<? super InputT, ?, OutputT> combineFn, Coder<InputT> inputTCoder) {
+
+    if (combineFn instanceof Combine.CombineFn) {
+      return new Combine.CombineFn<Object, Object, OutputT>() {
+
+        @SuppressWarnings("unchecked")
+        final Combine.CombineFn<InputT, Object, OutputT> fn =
+            (Combine.CombineFn<InputT, Object, OutputT>) combineFn;
+
+        @Override
+        public Object createAccumulator() {
+          return fn.createAccumulator();
+        }
+
+        @Override
+        public Coder<Object> getAccumulatorCoder(CoderRegistry registry, Coder<Object> inputCoder)
+            throws CannotProvideCoderException {
+          return fn.getAccumulatorCoder(registry, inputTCoder);
+        }
+
+        @Override
+        public Object addInput(Object mutableAccumulator, Object input) {
+          return fn.mergeAccumulators(ImmutableList.of(mutableAccumulator, input));
+        }
+
+        @Override
+        public Object mergeAccumulators(Iterable<Object> accumulators) {
+          return fn.mergeAccumulators(accumulators);
+        }
+
+        @Override
+        public OutputT extractOutput(Object accumulator) {
+          return fn.extractOutput(accumulator);
+        }
+      };
+    } else if (combineFn instanceof CombineWithContext.CombineFnWithContext) {
+      return new CombineWithContext.CombineFnWithContext<Object, Object, OutputT>() {
+
+        @SuppressWarnings("unchecked")
+        final CombineWithContext.CombineFnWithContext<InputT, Object, OutputT> fn =
+            (CombineWithContext.CombineFnWithContext<InputT, Object, OutputT>) combineFn;
+
+        @Override
+        public Object createAccumulator(CombineWithContext.Context c) {
+          return fn.createAccumulator(c);
+        }
+
+        @Override
+        public Coder<Object> getAccumulatorCoder(CoderRegistry registry, Coder<Object> inputCoder)
+            throws CannotProvideCoderException {
+          return fn.getAccumulatorCoder(registry, inputTCoder);
+        }
+
+        @Override
+        public Object addInput(Object accumulator, Object input, CombineWithContext.Context c) {
+          return fn.mergeAccumulators(ImmutableList.of(accumulator, input), c);
+        }
+
+        @Override
+        public Object mergeAccumulators(
+            Iterable<Object> accumulators, CombineWithContext.Context c) {
+          return fn.mergeAccumulators(accumulators, c);
+        }
+
+        @Override
+        public OutputT extractOutput(Object accumulator, CombineWithContext.Context c) {
+          return fn.extractOutput(accumulator, c);
+        }
+      };
+    }
+    throw new IllegalArgumentException(
+        "Unsupported CombineFn implementation: " + combineFn.getClass());
+  }
+
+  /**
+   * Create a DoFnOperator instance that group elements per window and apply a combine function on them.
+   */
+  public static <K, InputC, OutputC, InputT, OutputT> WindowDoFnOperator<K, InputC, OutputC> getWindowedAggregateDoFnOperator(
+      FlinkStreamingTranslationContext context,
+      PTransform<PCollection<KV<K, InputT>>, PCollection<KV<K, OutputT>>> transform,
+      KvCoder<K, InputC> inputKvCoder,
+      Coder<WindowedValue<KV<K, OutputC>>> outputCoder,
+      SystemReduceFn<K, InputC, ?, OutputC, BoundedWindow> reduceFn,
+      Map<Integer, PCollectionView<?>> sideInputTagMapping,
+      List<PCollectionView<?>> sideInputs) {
+
+    // Naming
+    String fullName = FlinkStreamingTransformTranslators.getCurrentTransformName(context);
+    TupleTag<KV<K, OutputC>> mainTag = new TupleTag<>("main output");
+
+    // input infos
+    PCollection<KV<K, InputT>> input = context.getInput(transform);
+
+    @SuppressWarnings("unchecked")
+    WindowingStrategy<?, BoundedWindow> windowingStrategy =
+        (WindowingStrategy<?, BoundedWindow>) input.getWindowingStrategy();
+    SerializablePipelineOptions serializablePipelineOptions =
+        new SerializablePipelineOptions(context.getPipelineOptions());
+
+    // Coders
+    Coder<K> keyCoder = inputKvCoder.getKeyCoder();
+
+    SingletonKeyedWorkItemCoder<K, InputC> workItemCoder =
+        SingletonKeyedWorkItemCoder.of(
+            keyCoder,
+            inputKvCoder.getValueCoder(),
+            windowingStrategy.getWindowFn().windowCoder());
+
+    WindowedValue.FullWindowedValueCoder<KeyedWorkItem<K, InputC>> windowedWorkItemCoder =
+        WindowedValue.getFullCoder(workItemCoder, windowingStrategy.getWindowFn().windowCoder());
+
+    // Key selector
+    WorkItemKeySelector<K, InputC> workItemKeySelector =
+        new WorkItemKeySelector<>(keyCoder, serializablePipelineOptions);
+
+    return new WindowDoFnOperator<>(
+        reduceFn,
+        fullName,
+        (Coder) windowedWorkItemCoder,
+        mainTag,
+        Collections.emptyList(),
+        new DoFnOperator.MultiOutputOutputManagerFactory<>(
+            mainTag, outputCoder, serializablePipelineOptions),
+        windowingStrategy,
+        sideInputTagMapping,
+        sideInputs,
+        context.getPipelineOptions(),
+        keyCoder,
+        workItemKeySelector);
+  }
+
+  public static <K, InputC, OutputC, InputT, OutputT> WindowDoFnOperator<K, InputC, OutputC> getWindowedAggregateDoFnOperator(
+      FlinkStreamingTranslationContext context,
+      PTransform<PCollection<KV<K, InputT>>, PCollection<KV<K, OutputT>>> transform,
+      KvCoder<K, InputC> inputKvCoder,
+      Coder<WindowedValue<KV<K, OutputC>>> outputCoder,
+      CombineFnBase.GlobalCombineFn<? super InputC, ?, OutputC> combineFn,
+      Map<Integer, PCollectionView<?>> sideInputTagMapping,
+      List<PCollectionView<?>> sideInputs) {
+
+    // Combining fn
+    SystemReduceFn<K, InputC, ?, OutputC, BoundedWindow> reduceFn =
+        SystemReduceFn.combining(
+            inputKvCoder.getKeyCoder(),
+            AppliedCombineFn.withInputCoder(
+                combineFn, context.getInput(transform).getPipeline().getCoderRegistry(), inputKvCoder));
+
+    return getWindowedAggregateDoFnOperator(context, transform, inputKvCoder, outputCoder, reduceFn, sideInputTagMapping, sideInputs);
+  }
+
+  public static <K, InputT, AccumT, OutputT> SingleOutputStreamOperator<WindowedValue<KV<K, OutputT>>> batchCombinePerKeyNoSideInputs(
+      FlinkStreamingTranslationContext context,
+      PTransform<PCollection<KV<K, InputT>>, PCollection<KV<K, OutputT>>> transform,
+      CombineFnBase.GlobalCombineFn<InputT, AccumT, OutputT> combineFn) {
+
+    Coder<WindowedValue<KV<K, AccumT>>> windowedAccumCoder;
+    KvCoder<K, AccumT> accumKvCoder;
+
+    PCollection<KV<K, InputT>> input = context.getInput(transform);
+    String fullName = FlinkStreamingTransformTranslators.getCurrentTransformName(context);
+    DataStream<WindowedValue<KV<K, InputT>>> inputDataStream = context.getInputDataStream(input);
+    KvCoder<K, InputT> inputKvCoder =
+        (KvCoder<K, InputT>) input.getCoder();
+    Coder<WindowedValue<KV<K, OutputT>>> outputCoder =
+        context.getWindowedInputCoder(context.getOutput(transform));
+    SerializablePipelineOptions serializablePipelineOptions =
+        new SerializablePipelineOptions(context.getPipelineOptions());
+    TypeInformation<WindowedValue<KV<K, OutputT>>> outputTypeInfo =
+        context.getTypeInfo(context.getOutput(transform));
+
+    try {
+      Coder<AccumT> accumulatorCoder =
+          combineFn.getAccumulatorCoder(
+              input.getPipeline().getCoderRegistry(), inputKvCoder.getValueCoder());
+
+      accumKvCoder = KvCoder.of(inputKvCoder.getKeyCoder(), accumulatorCoder);
+
+      windowedAccumCoder =
+          WindowedValue.getFullCoder(
+              accumKvCoder, input.getWindowingStrategy().getWindowFn().windowCoder());
+    } catch (CannotProvideCoderException e) {
+      throw new RuntimeException(e);
+    }
+
+    TupleTag<KV<K, AccumT>> mainTag = new TupleTag<>("main output");
+
+    PartialReduceBundleOperator<K, InputT, OutputT, AccumT> partialDoFnOperator =
+        new PartialReduceBundleOperator<>(
+            combineFn,
+            FlinkStreamingTransformTranslators.getCurrentTransformName(context),
+            context.getWindowedInputCoder(input),
+            mainTag,
+            Collections.emptyList(),
+            new DoFnOperator.MultiOutputOutputManagerFactory<>(
+                mainTag, windowedAccumCoder, serializablePipelineOptions),
+            input.getWindowingStrategy(),
+            new HashMap<>(),
+            Collections.emptyList(),
+            context.getPipelineOptions());
+
+    // final aggregation from AccumT to OutputT
+    WindowDoFnOperator<K, AccumT, OutputT> finalDoFnOperator =
+        getWindowedAggregateDoFnOperator(
+            context,
+            transform,
+            accumKvCoder,
+            outputCoder,
+            toFinalFlinkCombineFn(combineFn, inputKvCoder.getValueCoder()),
+            new HashMap<>(),
+            Collections.emptyList());
+
+    String partialName = "Combine: " + fullName;
+    CoderTypeInformation<WindowedValue<KV<K, AccumT>>> partialTypeInfo =
+        new CoderTypeInformation<>(windowedAccumCoder, context.getPipelineOptions());
+
+    return
+        inputDataStream
+            .transform(partialName, partialTypeInfo, partialDoFnOperator)
+            .uid(partialName)
+            .keyBy(new KvToByteBufferKeySelector<>(inputKvCoder.getKeyCoder(), serializablePipelineOptions))
+            .transform(fullName, outputTypeInfo, finalDoFnOperator)
+            .uid(fullName);
+  }
+}
diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingTransformTranslators.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingTransformTranslators.java
index 9ba19722cfd3..dc6e261a6360 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingTransformTranslators.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingTransformTranslators.java
@@ -21,6 +21,7 @@
 import static org.apache.beam.sdk.util.construction.SplittableParDo.SPLITTABLE_PROCESS_URN;
 
 import com.google.auto.service.AutoService;
+
 import java.io.IOException;
 import java.nio.ByteBuffer;
 import java.util.ArrayList;
@@ -29,17 +30,14 @@
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
-import org.apache.beam.runners.core.KeyedWorkItem;
-import org.apache.beam.runners.core.KeyedWorkItemCoder;
-import org.apache.beam.runners.core.SplittableParDoViaKeyedWorkItems;
-import org.apache.beam.runners.core.SystemReduceFn;
+
+import org.apache.beam.runners.core.*;
 import org.apache.beam.runners.core.construction.SerializablePipelineOptions;
 import org.apache.beam.runners.flink.translation.functions.FlinkAssignWindows;
 import org.apache.beam.runners.flink.translation.functions.ImpulseSourceFunction;
 import org.apache.beam.runners.flink.translation.types.CoderTypeInformation;
 import org.apache.beam.runners.flink.translation.wrappers.streaming.DoFnOperator;
 import org.apache.beam.runners.flink.translation.wrappers.streaming.KvToByteBufferKeySelector;
-import org.apache.beam.runners.flink.translation.wrappers.streaming.PartialReduceBundleOperator;
 import org.apache.beam.runners.flink.translation.wrappers.streaming.ProcessingTimeCallbackCompat;
 import org.apache.beam.runners.flink.translation.wrappers.streaming.SingletonKeyedWorkItem;
 import org.apache.beam.runners.flink.translation.wrappers.streaming.SingletonKeyedWorkItemCoder;
@@ -53,14 +51,7 @@
 import org.apache.beam.runners.flink.translation.wrappers.streaming.io.source.FlinkSource;
 import org.apache.beam.runners.flink.translation.wrappers.streaming.io.source.bounded.FlinkBoundedSource;
 import org.apache.beam.runners.flink.translation.wrappers.streaming.io.source.unbounded.FlinkUnboundedSource;
-import org.apache.beam.sdk.coders.ByteArrayCoder;
-import org.apache.beam.sdk.coders.CannotProvideCoderException;
-import org.apache.beam.sdk.coders.Coder;
-import org.apache.beam.sdk.coders.CoderException;
-import org.apache.beam.sdk.coders.CoderRegistry;
-import org.apache.beam.sdk.coders.IterableCoder;
-import org.apache.beam.sdk.coders.KvCoder;
-import org.apache.beam.sdk.coders.VoidCoder;
+import org.apache.beam.sdk.coders.*;
 import org.apache.beam.sdk.io.BoundedSource;
 import org.apache.beam.sdk.io.FileSystems;
 import org.apache.beam.sdk.io.UnboundedSource;
@@ -69,7 +60,6 @@
 import org.apache.beam.sdk.testing.TestStream;
 import org.apache.beam.sdk.transforms.Combine;
 import org.apache.beam.sdk.transforms.CombineFnBase.GlobalCombineFn;
-import org.apache.beam.sdk.transforms.CombineWithContext;
 import org.apache.beam.sdk.transforms.DoFn;
 import org.apache.beam.sdk.transforms.DoFnSchemaInformation;
 import org.apache.beam.sdk.transforms.Impulse;
@@ -82,7 +72,6 @@
 import org.apache.beam.sdk.transforms.windowing.BoundedWindow;
 import org.apache.beam.sdk.transforms.windowing.GlobalWindow;
 import org.apache.beam.sdk.transforms.windowing.WindowFn;
-import org.apache.beam.sdk.util.AppliedCombineFn;
 import org.apache.beam.sdk.util.CoderUtils;
 import org.apache.beam.sdk.util.WindowedValue;
 import org.apache.beam.sdk.util.construction.PTransformTranslation;
@@ -101,7 +90,6 @@
 import org.apache.beam.sdk.values.ValueWithRecordId;
 import org.apache.beam.sdk.values.WindowingStrategy;
 import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.annotations.VisibleForTesting;
-import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.ImmutableList;
 import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.ImmutableMap;
 import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.Maps;
 import org.apache.flink.api.common.eventtime.WatermarkStrategy;
@@ -137,8 +125,8 @@
  * encountered Beam transformations into Flink one, based on the mapping available in this class.
  */
 @SuppressWarnings({
-  "rawtypes", // TODO(https://github.com/apache/beam/issues/20447)
-  "nullness" // TODO(https://github.com/apache/beam/issues/20497)
+    "rawtypes", // TODO(https://github.com/apache/beam/issues/20447)
+    "nullness" // TODO(https://github.com/apache/beam/issues/20497)
 })
 class FlinkStreamingTransformTranslators {
 
@@ -146,7 +134,9 @@ class FlinkStreamingTransformTranslators {
   //  Transform Translator Registry
   // --------------------------------------------------------------------------------------------
 
-  /** A map from a Transform URN to the translator. */
+  /**
+   * A map from a Transform URN to the translator.
+   */
   @SuppressWarnings("rawtypes")
   private static final Map<String, FlinkStreamingPipelineTranslator.StreamTransformTranslator>
       TRANSLATORS = new HashMap<>();
@@ -183,7 +173,7 @@ public static FlinkStreamingPipelineTranslator.StreamTransformTranslator<?> getT
   }
 
   @SuppressWarnings("unchecked")
-  private static String getCurrentTransformName(FlinkStreamingTranslationContext context) {
+  public static String getCurrentTransformName(FlinkStreamingTranslationContext context) {
     return context.getCurrentTransform().getFullName();
   }
 
@@ -193,7 +183,7 @@ private static String getCurrentTransformName(FlinkStreamingTranslationContext c
 
   private static class UnboundedReadSourceTranslator<T>
       extends FlinkStreamingPipelineTranslator.StreamTransformTranslator<
-          PTransform<PBegin, PCollection<T>>> {
+      PTransform<PBegin, PCollection<T>>> {
 
     @Override
     public void translateNode(
@@ -269,7 +259,7 @@ public void translateNode(
 
   static class ValueWithRecordIdKeySelector<T>
       implements KeySelector<WindowedValue<ValueWithRecordId<T>>, ByteBuffer>,
-          ResultTypeQueryable<ByteBuffer> {
+      ResultTypeQueryable<ByteBuffer> {
 
     @Override
     public ByteBuffer getKey(WindowedValue<ValueWithRecordId<T>> value) throws Exception {
@@ -342,7 +332,7 @@ void translateNode(Impulse transform, FlinkStreamingTranslationContext context)
 
   private static class ReadSourceTranslator<T>
       extends FlinkStreamingPipelineTranslator.StreamTransformTranslator<
-          PTransform<PBegin, PCollection<T>>> {
+      PTransform<PBegin, PCollection<T>>> {
 
     private final BoundedReadSourceTranslator<T> boundedTranslator =
         new BoundedReadSourceTranslator<>();
@@ -363,7 +353,7 @@ void translateNode(
 
   private static class BoundedReadSourceTranslator<T>
       extends FlinkStreamingPipelineTranslator.StreamTransformTranslator<
-          PTransform<PBegin, PCollection<T>>> {
+      PTransform<PBegin, PCollection<T>>> {
 
     @Override
     public void translateNode(
@@ -415,7 +405,9 @@ public void translateNode(
     }
   }
 
-  /** Wraps each element in a {@link RawUnionValue} with the given tag id. */
+  /**
+   * Wraps each element in a {@link RawUnionValue} with the given tag id.
+   */
   public static class ToRawUnion<T> extends RichMapFunction<T, RawUnionValue> {
     private final int intTag;
     private final SerializablePipelineOptions options;
@@ -439,8 +431,8 @@ public RawUnionValue map(T o) throws Exception {
   }
 
   private static Tuple2<Map<Integer, PCollectionView<?>>, DataStream<RawUnionValue>>
-      transformSideInputs(
-          Collection<PCollectionView<?>> sideInputs, FlinkStreamingTranslationContext context) {
+  transformSideInputs(
+      Collection<PCollectionView<?>> sideInputs, FlinkStreamingTranslationContext context) {
 
     // collect all side inputs
     Map<TupleTag<?>, Integer> tagToIntMapping = new HashMap<>();
@@ -663,15 +655,15 @@ static <InputT, OutputT> void translateParDo(
           // allowed to have only one input keyed, normally.
           KeyedStream keyedStream = (KeyedStream<?, InputT>) inputDataStream;
           TwoInputTransformation<
-                  WindowedValue<KV<?, InputT>>, RawUnionValue, WindowedValue<OutputT>>
+              WindowedValue<KV<?, InputT>>, RawUnionValue, WindowedValue<OutputT>>
               rawFlinkTransform =
-                  new TwoInputTransformation(
-                      keyedStream.getTransformation(),
-                      transformedSideInputs.f1.broadcast().getTransformation(),
-                      transformName,
-                      doFnOperator,
-                      outputTypeInformation,
-                      keyedStream.getParallelism());
+              new TwoInputTransformation(
+                  keyedStream.getTransformation(),
+                  transformedSideInputs.f1.broadcast().getTransformation(),
+                  transformName,
+                  doFnOperator,
+                  outputTypeInformation,
+                  keyedStream.getParallelism());
 
           rawFlinkTransform.setStateKeyType(keyedStream.getKeyType());
           rawFlinkTransform.setStateKeySelectors(keyedStream.getKeySelector(), null);
@@ -679,7 +671,8 @@ static <InputT, OutputT> void translateParDo(
           outputStream =
               new SingleOutputStreamOperator(
                   keyedStream.getExecutionEnvironment(),
-                  rawFlinkTransform) {}; // we have to cheat around the ctor being protected
+                  rawFlinkTransform) {
+              }; // we have to cheat around the ctor being protected
 
           keyedStream.getExecutionEnvironment().addOperator(rawFlinkTransform);
 
@@ -705,7 +698,7 @@ static <InputT, OutputT> void translateParDo(
 
   private static class ParDoStreamingTranslator<InputT, OutputT>
       extends FlinkStreamingPipelineTranslator.StreamTransformTranslator<
-          PTransform<PCollection<InputT>, PCollectionTuple>> {
+      PTransform<PCollection<InputT>, PCollectionTuple>> {
 
     @Override
     public void translateNode(
@@ -760,22 +753,22 @@ public void translateNode(
           sideInputMapping,
           context,
           (doFn1,
-              stepName,
-              sideInputs1,
-              mainOutputTag1,
-              additionalOutputTags1,
-              context1,
-              windowingStrategy,
-              tagsToOutputTags,
-              tagsToCoders,
-              tagsToIds,
-              windowedInputCoder,
-              outputCoders1,
-              keyCoder,
-              keySelector,
-              transformedSideInputs,
-              doFnSchemaInformation1,
-              sideInputMapping1) ->
+           stepName,
+           sideInputs1,
+           mainOutputTag1,
+           additionalOutputTags1,
+           context1,
+           windowingStrategy,
+           tagsToOutputTags,
+           tagsToCoders,
+           tagsToIds,
+           windowedInputCoder,
+           outputCoders1,
+           keyCoder,
+           keySelector,
+           transformedSideInputs,
+           doFnSchemaInformation1,
+           sideInputMapping1) ->
               new DoFnOperator<>(
                   doFn1,
                   stepName,
@@ -801,15 +794,15 @@ public void translateNode(
   }
 
   private static class SplittableProcessElementsStreamingTranslator<
-          InputT, OutputT, RestrictionT, PositionT, WatermarkEstimatorStateT>
+      InputT, OutputT, RestrictionT, PositionT, WatermarkEstimatorStateT>
       extends FlinkStreamingPipelineTranslator.StreamTransformTranslator<
-          SplittableParDoViaKeyedWorkItems.ProcessElements<
-              InputT, OutputT, RestrictionT, PositionT, WatermarkEstimatorStateT>> {
+      SplittableParDoViaKeyedWorkItems.ProcessElements<
+          InputT, OutputT, RestrictionT, PositionT, WatermarkEstimatorStateT>> {
 
     @Override
     public void translateNode(
         SplittableParDoViaKeyedWorkItems.ProcessElements<
-                InputT, OutputT, RestrictionT, PositionT, WatermarkEstimatorStateT>
+            InputT, OutputT, RestrictionT, PositionT, WatermarkEstimatorStateT>
             transform,
         FlinkStreamingTranslationContext context) {
 
@@ -825,22 +818,22 @@ public void translateNode(
           Collections.emptyMap(),
           context,
           (doFn,
-              stepName,
-              sideInputs,
-              mainOutputTag,
-              additionalOutputTags,
-              context1,
-              windowingStrategy,
-              tagsToOutputTags,
-              tagsToCoders,
-              tagsToIds,
-              windowedInputCoder,
-              outputCoders1,
-              keyCoder,
-              keySelector,
-              transformedSideInputs,
-              doFnSchemaInformation,
-              sideInputMapping) ->
+           stepName,
+           sideInputs,
+           mainOutputTag,
+           additionalOutputTags,
+           context1,
+           windowingStrategy,
+           tagsToOutputTags,
+           tagsToCoders,
+           tagsToIds,
+           windowedInputCoder,
+           outputCoders1,
+           keyCoder,
+           keySelector,
+           transformedSideInputs,
+           doFnSchemaInformation,
+           sideInputMapping) ->
               new SplittableDoFnOperator<>(
                   doFn,
                   stepName,
@@ -865,7 +858,7 @@ public void translateNode(
 
   private static class CreateViewStreamingTranslator<ElemT, ViewT>
       extends FlinkStreamingPipelineTranslator.StreamTransformTranslator<
-          CreateStreamingFlinkView.CreateFlinkPCollectionView<ElemT, ViewT>> {
+      CreateStreamingFlinkView.CreateFlinkPCollectionView<ElemT, ViewT>> {
 
     @Override
     public void translateNode(
@@ -883,7 +876,7 @@ public void translateNode(
 
   private static class WindowAssignTranslator<T>
       extends FlinkStreamingPipelineTranslator.StreamTransformTranslator<
-          PTransform<PCollection<T>, PCollection<T>>> {
+      PTransform<PCollection<T>, PCollection<T>>> {
 
     @Override
     public void translateNode(
@@ -919,7 +912,7 @@ public void translateNode(
 
   private static class ReshuffleTranslatorStreaming<K, InputT>
       extends FlinkStreamingPipelineTranslator.StreamTransformTranslator<
-          PTransform<PCollection<KV<K, InputT>>, PCollection<KV<K, InputT>>>> {
+      PTransform<PCollection<KV<K, InputT>>, PCollection<KV<K, InputT>>>> {
 
     @Override
     public void translateNode(
@@ -935,7 +928,7 @@ public void translateNode(
 
   private static class GroupByKeyTranslator<K, InputT>
       extends FlinkStreamingPipelineTranslator.StreamTransformTranslator<
-          PTransform<PCollection<KV<K, InputT>>, PCollection<KV<K, Iterable<InputT>>>>> {
+      PTransform<PCollection<KV<K, InputT>>, PCollection<KV<K, Iterable<InputT>>>>> {
 
     @Override
     public void translateNode(
@@ -943,79 +936,62 @@ public void translateNode(
         FlinkStreamingTranslationContext context) {
 
       PCollection<KV<K, InputT>> input = context.getInput(transform);
-
       @SuppressWarnings("unchecked")
       WindowingStrategy<?, BoundedWindow> windowingStrategy =
           (WindowingStrategy<?, BoundedWindow>) input.getWindowingStrategy();
-
       KvCoder<K, InputT> inputKvCoder = (KvCoder<K, InputT>) input.getCoder();
-
       DataStream<WindowedValue<KV<K, InputT>>> inputDataStream = context.getInputDataStream(input);
-
-      WindowedValue.FullWindowedValueCoder<KeyedWorkItem<K, InputT>> windowedKeyedWorkItemCoder =
-          WindowedValue.getFullCoder(
-              KeyedWorkItemCoder.of(
-                  inputKvCoder.getKeyCoder(),
-                  inputKvCoder.getValueCoder(),
-                  input.getWindowingStrategy().getWindowFn().windowCoder()),
-              input.getWindowingStrategy().getWindowFn().windowCoder());
-
-      KvToByteBufferKeySelector<K, InputT> keySelector =
-          new KvToByteBufferKeySelector<>(
-              inputKvCoder.getKeyCoder(),
-              new SerializablePipelineOptions(context.getPipelineOptions()));
-
-      KeyedStream<WindowedValue<KV<K, InputT>>, ByteBuffer> keyedWorkItemStream =
-          inputDataStream.keyBy(keySelector);
-
-      SystemReduceFn<K, InputT, Iterable<InputT>, Iterable<InputT>, BoundedWindow> reduceFn =
-          SystemReduceFn.buffering(inputKvCoder.getValueCoder());
-
-      Coder<WindowedValue<KV<K, Iterable<InputT>>>> outputCoder =
-          WindowedValue.getFullCoder(
-              KvCoder.of(
-                  inputKvCoder.getKeyCoder(), IterableCoder.of(inputKvCoder.getValueCoder())),
-              windowingStrategy.getWindowFn().windowCoder());
-
-      TypeInformation<WindowedValue<KV<K, Iterable<InputT>>>> outputTypeInfo =
-          new CoderTypeInformation<>(outputCoder, context.getPipelineOptions());
-
-      TupleTag<KV<K, Iterable<InputT>>> mainTag = new TupleTag<>("main output");
-
-      WorkItemKeySelector<K, InputT> workItemKeySelector =
-          new WorkItemKeySelector<>(
-              inputKvCoder.getKeyCoder(),
-              new SerializablePipelineOptions(context.getPipelineOptions()));
-
       String fullName = getCurrentTransformName(context);
-      WindowDoFnOperator<K, InputT, Iterable<InputT>> doFnOperator =
-          new WindowDoFnOperator<>(
-              reduceFn,
-              fullName,
-              windowedKeyedWorkItemCoder,
-              mainTag,
-              Collections.emptyList(),
-              new DoFnOperator.MultiOutputOutputManagerFactory<>(
-                  mainTag,
-                  outputCoder,
-                  new SerializablePipelineOptions(context.getPipelineOptions())),
-              windowingStrategy,
-              new HashMap<>(), /* side-input mapping */
-              Collections.emptyList(), /* side inputs */
-              context.getPipelineOptions(),
-              inputKvCoder.getKeyCoder(),
-              workItemKeySelector);
 
-      final SingleOutputStreamOperator<WindowedValue<KV<K, Iterable<InputT>>>> outDataStream =
-          keyedWorkItemStream.transform(fullName, outputTypeInfo, doFnOperator).uid(fullName);
+      SingleOutputStreamOperator<WindowedValue<KV<K, Iterable<InputT>>>> outDataStream;
+      // Pre-aggregate before shuffle similar to group combine
+      if (!context.isStreaming()) {
+        outDataStream =
+            FlinkStreamingAggregationsTranslators.batchCombinePerKeyNoSideInputs(
+                context,
+                transform,
+                new FlinkStreamingAggregationsTranslators.ConcatenateAsIterable<>());
+      } else {
+        // No pre-aggregation in Streaming mode.
+        KvToByteBufferKeySelector<K, InputT> keySelector =
+            new KvToByteBufferKeySelector<>(
+                inputKvCoder.getKeyCoder(),
+                new SerializablePipelineOptions(context.getPipelineOptions()));
+
+        Coder<WindowedValue<KV<K, Iterable<InputT>>>> outputCoder =
+            WindowedValue.getFullCoder(
+                KvCoder.of(
+                    inputKvCoder.getKeyCoder(), IterableCoder.of(inputKvCoder.getValueCoder())),
+                windowingStrategy.getWindowFn().windowCoder());
+
+        TypeInformation<WindowedValue<KV<K, Iterable<InputT>>>> outputTypeInfo =
+            new CoderTypeInformation<>(outputCoder, context.getPipelineOptions());
+
+        WindowDoFnOperator<K, InputT, Iterable<InputT>> doFnOperator =
+          FlinkStreamingAggregationsTranslators.getWindowedAggregateDoFnOperator(
+              context,
+              transform,
+              inputKvCoder,
+              outputCoder,
+              SystemReduceFn.buffering(inputKvCoder.getValueCoder()),
+              new HashMap<>(),
+              Collections.emptyList());
+
+        outDataStream =
+            inputDataStream
+                .keyBy(keySelector)
+                .transform(fullName, outputTypeInfo, doFnOperator)
+                .uid(fullName);
 
+      }
       context.setOutputDataStream(context.getOutput(transform), outDataStream);
+
     }
   }
 
   private static class CombinePerKeyTranslator<K, InputT, OutputT>
       extends FlinkStreamingPipelineTranslator.StreamTransformTranslator<
-          PTransform<PCollection<KV<K, InputT>>, PCollection<KV<K, OutputT>>>> {
+      PTransform<PCollection<KV<K, InputT>>, PCollection<KV<K, OutputT>>>> {
 
     @Override
     boolean canTranslate(
@@ -1034,142 +1010,6 @@ boolean canTranslate(
           || ((Combine.PerKey) transform).getSideInputs().isEmpty();
     }
 
-    private static <InputT, OutputT> GlobalCombineFn<Object, Object, OutputT> toFinalFlinkCombineFn(
-        GlobalCombineFn<? super InputT, ?, OutputT> combineFn, Coder<InputT> inputTCoder) {
-
-      if (combineFn instanceof Combine.CombineFn) {
-        return new Combine.CombineFn<Object, Object, OutputT>() {
-
-          @SuppressWarnings("unchecked")
-          final Combine.CombineFn<InputT, Object, OutputT> fn =
-              (Combine.CombineFn<InputT, Object, OutputT>) combineFn;
-
-          @Override
-          public Object createAccumulator() {
-            return fn.createAccumulator();
-          }
-
-          @Override
-          public Coder<Object> getAccumulatorCoder(CoderRegistry registry, Coder<Object> inputCoder)
-              throws CannotProvideCoderException {
-            return fn.getAccumulatorCoder(registry, inputTCoder);
-          }
-
-          @Override
-          public Object addInput(Object mutableAccumulator, Object input) {
-            return fn.mergeAccumulators(ImmutableList.of(mutableAccumulator, input));
-          }
-
-          @Override
-          public Object mergeAccumulators(Iterable<Object> accumulators) {
-            return fn.mergeAccumulators(accumulators);
-          }
-
-          @Override
-          public OutputT extractOutput(Object accumulator) {
-            return fn.extractOutput(accumulator);
-          }
-        };
-      } else if (combineFn instanceof CombineWithContext.CombineFnWithContext) {
-        return new CombineWithContext.CombineFnWithContext<Object, Object, OutputT>() {
-
-          @SuppressWarnings("unchecked")
-          final CombineWithContext.CombineFnWithContext<InputT, Object, OutputT> fn =
-              (CombineWithContext.CombineFnWithContext<InputT, Object, OutputT>) combineFn;
-
-          @Override
-          public Object createAccumulator(CombineWithContext.Context c) {
-            return fn.createAccumulator(c);
-          }
-
-          @Override
-          public Coder<Object> getAccumulatorCoder(CoderRegistry registry, Coder<Object> inputCoder)
-              throws CannotProvideCoderException {
-            return fn.getAccumulatorCoder(registry, inputTCoder);
-          }
-
-          @Override
-          public Object addInput(Object accumulator, Object input, CombineWithContext.Context c) {
-            return fn.mergeAccumulators(ImmutableList.of(accumulator, input), c);
-          }
-
-          @Override
-          public Object mergeAccumulators(
-              Iterable<Object> accumulators, CombineWithContext.Context c) {
-            return fn.mergeAccumulators(accumulators, c);
-          }
-
-          @Override
-          public OutputT extractOutput(Object accumulator, CombineWithContext.Context c) {
-            return fn.extractOutput(accumulator, c);
-          }
-        };
-      }
-      throw new IllegalArgumentException(
-          "Unsupported CombineFn implementation: " + combineFn.getClass());
-    }
-
-    private static <K, InputC, OutputC, InputT, OutputT>
-        WindowDoFnOperator<K, InputC, OutputC> getDoFnOperator(
-            FlinkStreamingTranslationContext context,
-            PTransform<PCollection<KV<K, InputT>>, PCollection<KV<K, OutputT>>> transform,
-            KvCoder<K, InputC> inputKvCoder,
-            Coder<WindowedValue<KV<K, OutputC>>> outputCoder,
-            GlobalCombineFn<? super InputC, ?, OutputC> combineFn,
-            Map<Integer, PCollectionView<?>> sideInputTagMapping,
-            List<PCollectionView<?>> sideInputs) {
-
-      // Naming
-      String fullName = getCurrentTransformName(context);
-      TupleTag<KV<K, OutputC>> mainTag = new TupleTag<>("main output");
-
-      // input infos
-      PCollection<KV<K, InputT>> input = context.getInput(transform);
-      @SuppressWarnings("unchecked")
-      WindowingStrategy<?, BoundedWindow> windowingStrategy =
-          (WindowingStrategy<?, BoundedWindow>) input.getWindowingStrategy();
-      SerializablePipelineOptions serializablePipelineOptions =
-          new SerializablePipelineOptions(context.getPipelineOptions());
-
-      // Coders
-      Coder<K> keyCoder = inputKvCoder.getKeyCoder();
-
-      SingletonKeyedWorkItemCoder<K, InputC> workItemCoder =
-          SingletonKeyedWorkItemCoder.of(
-              keyCoder,
-              inputKvCoder.getValueCoder(),
-              windowingStrategy.getWindowFn().windowCoder());
-
-      WindowedValue.FullWindowedValueCoder<KeyedWorkItem<K, InputC>> windowedWorkItemCoder =
-          WindowedValue.getFullCoder(workItemCoder, windowingStrategy.getWindowFn().windowCoder());
-
-      // Combining fn
-      SystemReduceFn<K, InputC, ?, OutputC, BoundedWindow> reduceFn =
-          SystemReduceFn.combining(
-              keyCoder,
-              AppliedCombineFn.withInputCoder(
-                  combineFn, input.getPipeline().getCoderRegistry(), inputKvCoder));
-
-      // Key selector
-      WorkItemKeySelector<K, InputC> workItemKeySelector =
-          new WorkItemKeySelector<>(keyCoder, serializablePipelineOptions);
-
-      return new WindowDoFnOperator<>(
-          reduceFn,
-          fullName,
-          (Coder) windowedWorkItemCoder,
-          mainTag,
-          Collections.emptyList(),
-          new DoFnOperator.MultiOutputOutputManagerFactory<>(
-              mainTag, outputCoder, serializablePipelineOptions),
-          windowingStrategy,
-          sideInputTagMapping,
-          sideInputs,
-          context.getPipelineOptions(),
-          keyCoder,
-          workItemKeySelector);
-    }
-
     @Override
     public void translateNode(
         PTransform<PCollection<KV<K, InputT>>, PCollection<KV<K, OutputT>>> transform,
@@ -1183,7 +1023,8 @@ public void translateNode(
       Coder<WindowedValue<KV<K, OutputT>>> outputCoder =
           context.getWindowedInputCoder(context.getOutput(transform));
 
-      DataStream<WindowedValue<KV<K, InputT>>> inputDataStream = context.getInputDataStream(input);
+      DataStream<WindowedValue<KV<K, InputT>>> inputDataStream =
+          context.getInputDataStream(input);
 
       SerializablePipelineOptions serializablePipelineOptions =
           new SerializablePipelineOptions(context.getPipelineOptions());
@@ -1205,65 +1046,10 @@ public void translateNode(
         SingleOutputStreamOperator<WindowedValue<KV<K, OutputT>>> outDataStream;
 
         if (!context.isStreaming()) {
-          Coder<WindowedValue<KV<K, Object>>> windowedAccumCoder;
-          KvCoder<K, Object> accumKvCoder;
-          try {
-            @SuppressWarnings("unchecked")
-            Coder<Object> accumulatorCoder =
-                (Coder<Object>)
-                    combineFn.getAccumulatorCoder(
-                        input.getPipeline().getCoderRegistry(), inputKvCoder.getValueCoder());
-
-            accumKvCoder = KvCoder.of(inputKvCoder.getKeyCoder(), accumulatorCoder);
-
-            windowedAccumCoder =
-                WindowedValue.getFullCoder(
-                    accumKvCoder, input.getWindowingStrategy().getWindowFn().windowCoder());
-          } catch (CannotProvideCoderException e) {
-            throw new RuntimeException(e);
-          }
-
-          TupleTag<KV<K, Object>> mainTag = new TupleTag<>("main output");
-
-          PartialReduceBundleOperator<K, InputT, OutputT, Object> partialDoFnOperator =
-              new PartialReduceBundleOperator<>(
-                  (GlobalCombineFn<InputT, Object, OutputT>) combineFn,
-                  getCurrentTransformName(context),
-                  context.getWindowedInputCoder(input),
-                  mainTag,
-                  Collections.emptyList(),
-                  new DoFnOperator.MultiOutputOutputManagerFactory<>(
-                      mainTag, windowedAccumCoder, serializablePipelineOptions),
-                  input.getWindowingStrategy(),
-                  new HashMap<>(),
-                  Collections.emptyList(),
-                  context.getPipelineOptions());
-
-          // final aggregation from AccumT to OutputT
-          WindowDoFnOperator<K, Object, OutputT> finalDoFnOperator =
-              getDoFnOperator(
-                  context,
-                  transform,
-                  accumKvCoder,
-                  outputCoder,
-                  toFinalFlinkCombineFn(combineFn, inputKvCoder.getValueCoder()),
-                  new HashMap<>(),
-                  Collections.emptyList());
-
-          String partialName = "Combine: " + fullName;
-          CoderTypeInformation<WindowedValue<KV<K, Object>>> partialTypeInfo =
-              new CoderTypeInformation<>(windowedAccumCoder, context.getPipelineOptions());
-
-          outDataStream =
-              inputDataStream
-                  .transform(partialName, partialTypeInfo, partialDoFnOperator)
-                  .uid(partialName)
-                  .keyBy(new KvToByteBufferKeySelector<>(keyCoder, serializablePipelineOptions))
-                  .transform(fullName, outputTypeInfo, finalDoFnOperator)
-                  .uid(fullName);
+          outDataStream = FlinkStreamingAggregationsTranslators.batchCombinePerKeyNoSideInputs(context, transform, combineFn);
         } else {
           WindowDoFnOperator<K, InputT, OutputT> doFnOperator =
-              getDoFnOperator(
+              FlinkStreamingAggregationsTranslators.getWindowedAggregateDoFnOperator(
                   context,
                   transform,
                   inputKvCoder,
@@ -1282,7 +1068,7 @@ public void translateNode(
             transformSideInputs(sideInputs, context);
 
         WindowDoFnOperator<K, InputT, OutputT> doFnOperator =
-            getDoFnOperator(
+            FlinkStreamingAggregationsTranslators.getWindowedAggregateDoFnOperator(
                 context,
                 transform,
                 inputKvCoder,
@@ -1295,15 +1081,15 @@ public void translateNode(
         // allowed to have only one input keyed, normally.
 
         TwoInputTransformation<
-                WindowedValue<KV<K, InputT>>, RawUnionValue, WindowedValue<KV<K, OutputT>>>
+            WindowedValue<KV<K, InputT>>, RawUnionValue, WindowedValue<KV<K, OutputT>>>
             rawFlinkTransform =
-                new TwoInputTransformation<>(
-                    keyedStream.getTransformation(),
-                    transformSideInputs.f1.broadcast().getTransformation(),
-                    transform.getName(),
-                    doFnOperator,
-                    outputTypeInfo,
-                    keyedStream.getParallelism());
+            new TwoInputTransformation<>(
+                keyedStream.getTransformation(),
+                transformSideInputs.f1.broadcast().getTransformation(),
+                transform.getName(),
+                doFnOperator,
+                outputTypeInfo,
+                keyedStream.getParallelism());
 
         rawFlinkTransform.setStateKeyType(keyedStream.getKeyType());
         rawFlinkTransform.setStateKeySelectors(keyedStream.getKeySelector(), null);
@@ -1312,7 +1098,8 @@ public void translateNode(
         SingleOutputStreamOperator<WindowedValue<KV<K, OutputT>>> outDataStream =
             new SingleOutputStreamOperator(
                 keyedStream.getExecutionEnvironment(),
-                rawFlinkTransform) {}; // we have to cheat around the ctor being protected
+                rawFlinkTransform) {
+            }; // we have to cheat around the ctor being protected
 
         keyedStream.getExecutionEnvironment().addOperator(rawFlinkTransform);
 
@@ -1323,7 +1110,7 @@ public void translateNode(
 
   private static class GBKIntoKeyedWorkItemsTranslator<K, InputT>
       extends FlinkStreamingPipelineTranslator.StreamTransformTranslator<
-          PTransform<PCollection<KV<K, InputT>>, PCollection<KeyedWorkItem<K, InputT>>>> {
+      PTransform<PCollection<KV<K, InputT>>, PCollection<KeyedWorkItem<K, InputT>>>> {
 
     @Override
     boolean canTranslate(
@@ -1373,7 +1160,7 @@ public void translateNode(
 
   private static class ToKeyedWorkItemInGlobalWindow<K, InputT>
       extends RichFlatMapFunction<
-          WindowedValue<KV<K, InputT>>, WindowedValue<KeyedWorkItem<K, InputT>>> {
+      WindowedValue<KV<K, InputT>>, WindowedValue<KeyedWorkItem<K, InputT>>> {
 
     private final SerializablePipelineOptions options;
 
@@ -1411,7 +1198,7 @@ public void flatMap(
 
   private static class FlattenPCollectionTranslator<T>
       extends FlinkStreamingPipelineTranslator.StreamTransformTranslator<
-          PTransform<PCollection<T>, PCollection<T>>> {
+      PTransform<PCollection<T>, PCollection<T>>> {
 
     @Override
     public void translateNode(
@@ -1479,14 +1266,16 @@ public void flatMap(T t, Collector<T> collector) throws Exception {
     }
   }
 
-  /** Registers classes specialized to the Flink runner. */
+  /**
+   * Registers classes specialized to the Flink runner.
+   */
   @AutoService(TransformPayloadTranslatorRegistrar.class)
   public static class FlinkTransformsRegistrar implements TransformPayloadTranslatorRegistrar {
     @Override
     public Map<
-            ? extends Class<? extends PTransform>,
-            ? extends PTransformTranslation.TransformPayloadTranslator>
-        getTransformPayloadTranslators() {
+        ? extends Class<? extends PTransform>,
+        ? extends PTransformTranslation.TransformPayloadTranslator>
+    getTransformPayloadTranslators() {
       return ImmutableMap
           .<Class<? extends PTransform>, PTransformTranslation.TransformPayloadTranslator>builder()
           .put(
@@ -1496,12 +1285,15 @@ public static class FlinkTransformsRegistrar implements TransformPayloadTranslat
     }
   }
 
-  /** A translator just to vend the URN. */
+  /**
+   * A translator just to vend the URN.
+   */
   private static class CreateStreamingFlinkViewPayloadTranslator
       extends PTransformTranslation.TransformPayloadTranslator.NotSerializable<
-          CreateStreamingFlinkView.CreateFlinkPCollectionView<?, ?>> {
+      CreateStreamingFlinkView.CreateFlinkPCollectionView<?, ?>> {
 
-    private CreateStreamingFlinkViewPayloadTranslator() {}
+    private CreateStreamingFlinkViewPayloadTranslator() {
+    }
 
     @Override
     public String getUrn() {
@@ -1509,7 +1301,9 @@ public String getUrn() {
     }
   }
 
-  /** A translator to support {@link TestStream} with Flink. */
+  /**
+   * A translator to support {@link TestStream} with Flink.
+   */
   private static class TestStreamTranslator<T>
       extends FlinkStreamingPipelineTranslator.StreamTransformTranslator<TestStream<T>> {
 
@@ -1555,7 +1349,7 @@ void translateNode(TestStream<T> testStream, FlinkStreamingTranslationContext co
    * {@link ValueWithRecordId}.
    */
   static class UnboundedSourceWrapperNoValueWithRecordId<
-          OutputT, CheckpointMarkT extends UnboundedSource.CheckpointMark>
+      OutputT, CheckpointMarkT extends UnboundedSource.CheckpointMark>
       extends RichParallelSourceFunction<WindowedValue<OutputT>>
       implements BeamStoppableFunction,
           CheckpointListener,

From f38fd11252c0b683300e83ce5362fc0c14136048 Mon Sep 17 00:00:00 2001
From: jto <boudhevil@gmail.com>
Date: Wed, 28 Aug 2024 16:18:55 +0200
Subject: [PATCH 12/26] [Flink] Combine before reduce (with side input)

---
 ...FlinkStreamingAggregationsTranslators.java | 102 +++++++++++++++---
 .../FlinkStreamingTransformTranslators.java   |  61 +++++------
 2 files changed, 110 insertions(+), 53 deletions(-)

diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingAggregationsTranslators.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingAggregationsTranslators.java
index 60e0a1a8a058..882a6fd18cd1 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingAggregationsTranslators.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingAggregationsTranslators.java
@@ -10,15 +10,20 @@
 import org.apache.beam.sdk.transforms.CombineFnBase;
 import org.apache.beam.sdk.transforms.CombineWithContext;
 import org.apache.beam.sdk.transforms.PTransform;
+import org.apache.beam.sdk.transforms.join.RawUnionValue;
 import org.apache.beam.sdk.transforms.windowing.BoundedWindow;
 import org.apache.beam.sdk.util.AppliedCombineFn;
 import org.apache.beam.sdk.util.WindowedValue;
 import org.apache.beam.sdk.values.*;
 import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.ImmutableList;
 import org.apache.flink.api.common.typeinfo.TypeInformation;
+import org.apache.flink.api.java.tuple.Tuple2;
 import org.apache.flink.streaming.api.datastream.DataStream;
+import org.apache.flink.streaming.api.datastream.KeyedStream;
 import org.apache.flink.streaming.api.datastream.SingleOutputStreamOperator;
+import org.apache.flink.streaming.api.transformations.TwoInputTransformation;
 
+import java.nio.ByteBuffer;
 import java.util.*;
 
 public class FlinkStreamingAggregationsTranslators {
@@ -210,10 +215,12 @@ public static <K, InputC, OutputC, InputT, OutputT> WindowDoFnOperator<K, InputC
     return getWindowedAggregateDoFnOperator(context, transform, inputKvCoder, outputCoder, reduceFn, sideInputTagMapping, sideInputs);
   }
 
-  public static <K, InputT, AccumT, OutputT> SingleOutputStreamOperator<WindowedValue<KV<K, OutputT>>> batchCombinePerKeyNoSideInputs(
+  public static <K, InputT, AccumT, OutputT> SingleOutputStreamOperator<WindowedValue<KV<K, OutputT>>> batchCombinePerKey(
       FlinkStreamingTranslationContext context,
       PTransform<PCollection<KV<K, InputT>>, PCollection<KV<K, OutputT>>> transform,
-      CombineFnBase.GlobalCombineFn<InputT, AccumT, OutputT> combineFn) {
+      CombineFnBase.GlobalCombineFn<InputT, AccumT, OutputT> combineFn,
+      Map<Integer, PCollectionView<?>> sideInputTagMapping,
+      List<PCollectionView<?>> sideInputs) {
 
     Coder<WindowedValue<KV<K, AccumT>>> windowedAccumCoder;
     KvCoder<K, AccumT> accumKvCoder;
@@ -249,17 +256,24 @@ public static <K, InputT, AccumT, OutputT> SingleOutputStreamOperator<WindowedVa
     PartialReduceBundleOperator<K, InputT, OutputT, AccumT> partialDoFnOperator =
         new PartialReduceBundleOperator<>(
             combineFn,
-            FlinkStreamingTransformTranslators.getCurrentTransformName(context),
+            fullName,
             context.getWindowedInputCoder(input),
             mainTag,
             Collections.emptyList(),
             new DoFnOperator.MultiOutputOutputManagerFactory<>(
                 mainTag, windowedAccumCoder, serializablePipelineOptions),
             input.getWindowingStrategy(),
-            new HashMap<>(),
-            Collections.emptyList(),
+            sideInputTagMapping,
+            sideInputs,
             context.getPipelineOptions());
 
+    String partialName = "Combine: " + fullName;
+    CoderTypeInformation<WindowedValue<KV<K, AccumT>>> partialTypeInfo =
+        new CoderTypeInformation<>(windowedAccumCoder, context.getPipelineOptions());
+
+    KvToByteBufferKeySelector<K, AccumT> accumKeySelector =
+        new KvToByteBufferKeySelector<>(inputKvCoder.getKeyCoder(), serializablePipelineOptions);
+
     // final aggregation from AccumT to OutputT
     WindowDoFnOperator<K, AccumT, OutputT> finalDoFnOperator =
         getWindowedAggregateDoFnOperator(
@@ -268,19 +282,73 @@ public static <K, InputT, AccumT, OutputT> SingleOutputStreamOperator<WindowedVa
             accumKvCoder,
             outputCoder,
             toFinalFlinkCombineFn(combineFn, inputKvCoder.getValueCoder()),
-            new HashMap<>(),
-            Collections.emptyList());
-
-    String partialName = "Combine: " + fullName;
-    CoderTypeInformation<WindowedValue<KV<K, AccumT>>> partialTypeInfo =
-        new CoderTypeInformation<>(windowedAccumCoder, context.getPipelineOptions());
-
-    return
-        inputDataStream
+            sideInputTagMapping,
+            sideInputs);
+
+    if(sideInputs.isEmpty()) {
+      return
+          inputDataStream
+              .transform(partialName, partialTypeInfo, partialDoFnOperator)
+              .uid(partialName)
+              .keyBy(accumKeySelector)
+              .transform(fullName, outputTypeInfo, finalDoFnOperator)
+              .uid(fullName);
+    } else {
+      Tuple2<Map<Integer, PCollectionView<?>>, DataStream<RawUnionValue>> transformSideInputs =
+          FlinkStreamingTransformTranslators.transformSideInputs(sideInputs, context);
+
+      KeyedStream<WindowedValue<KV<K, AccumT>>, ByteBuffer> keyedStream =
+          inputDataStream
             .transform(partialName, partialTypeInfo, partialDoFnOperator)
             .uid(partialName)
-            .keyBy(new KvToByteBufferKeySelector<>(inputKvCoder.getKeyCoder(), serializablePipelineOptions))
-            .transform(fullName, outputTypeInfo, finalDoFnOperator)
-            .uid(fullName);
+            .keyBy(accumKeySelector);
+
+      return buildTwoInputStream(keyedStream, transformSideInputs.f1, transform.getName(), finalDoFnOperator, outputTypeInfo);
+    }
+  }
+
+  @SuppressWarnings({
+      "nullness" // TODO(https://github.com/apache/beam/issues/20497)
+  })
+  public static <K, InputT, OutputT> SingleOutputStreamOperator<WindowedValue<KV<K, OutputT>>> buildTwoInputStream(
+      KeyedStream<WindowedValue<KV<K, InputT>>, ByteBuffer> keyedStream,
+      DataStream<RawUnionValue> sideInputStream,
+      String name,
+      WindowDoFnOperator<K, InputT, OutputT> operator,
+      TypeInformation<WindowedValue<KV<K, OutputT>>> outputTypeInfo
+  ) {
+    // we have to manually construct the two-input transform because we're not
+    // allowed to have only one input keyed, normally.
+    TwoInputTransformation<
+        WindowedValue<KV<K, InputT>>, RawUnionValue, WindowedValue<KV<K, OutputT>>>
+        rawFlinkTransform =
+        new TwoInputTransformation<>(
+            keyedStream.getTransformation(),
+            sideInputStream.broadcast().getTransformation(),
+            name,
+            operator,
+            outputTypeInfo,
+            keyedStream.getParallelism());
+
+    rawFlinkTransform.setStateKeyType(keyedStream.getKeyType());
+    rawFlinkTransform.setStateKeySelectors(keyedStream.getKeySelector(), null);
+
+    @SuppressWarnings({"unchecked", "rawtypes"})
+    SingleOutputStreamOperator<WindowedValue<KV<K, OutputT>>> outDataStream =
+        new SingleOutputStreamOperator(
+            keyedStream.getExecutionEnvironment(),
+            rawFlinkTransform) {
+        }; // we have to cheat around the ctor being protected
+
+    keyedStream.getExecutionEnvironment().addOperator(rawFlinkTransform);
+
+    return outDataStream;
+  }
+
+  public static <K, InputT, AccumT, OutputT> SingleOutputStreamOperator<WindowedValue<KV<K, OutputT>>> batchCombinePerKeyNoSideInputs(
+      FlinkStreamingTranslationContext context,
+      PTransform<PCollection<KV<K, InputT>>, PCollection<KV<K, OutputT>>> transform,
+      CombineFnBase.GlobalCombineFn<InputT, AccumT, OutputT> combineFn) {
+    return batchCombinePerKey(context, transform, combineFn, new HashMap<>(), Collections.emptyList());
   }
 }
diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingTransformTranslators.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingTransformTranslators.java
index dc6e261a6360..5b04cd587ab8 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingTransformTranslators.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingTransformTranslators.java
@@ -430,7 +430,7 @@ public RawUnionValue map(T o) throws Exception {
     }
   }
 
-  private static Tuple2<Map<Integer, PCollectionView<?>>, DataStream<RawUnionValue>>
+  public static Tuple2<Map<Integer, PCollectionView<?>>, DataStream<RawUnionValue>>
   transformSideInputs(
       Collection<PCollectionView<?>> sideInputs, FlinkStreamingTranslationContext context) {
 
@@ -1046,7 +1046,8 @@ public void translateNode(
         SingleOutputStreamOperator<WindowedValue<KV<K, OutputT>>> outDataStream;
 
         if (!context.isStreaming()) {
-          outDataStream = FlinkStreamingAggregationsTranslators.batchCombinePerKeyNoSideInputs(context, transform, combineFn);
+          outDataStream =
+              FlinkStreamingAggregationsTranslators.batchCombinePerKeyNoSideInputs(context, transform, combineFn);
         } else {
           WindowDoFnOperator<K, InputT, OutputT> doFnOperator =
               FlinkStreamingAggregationsTranslators.getWindowedAggregateDoFnOperator(
@@ -1066,42 +1067,30 @@ public void translateNode(
       } else {
         Tuple2<Map<Integer, PCollectionView<?>>, DataStream<RawUnionValue>> transformSideInputs =
             transformSideInputs(sideInputs, context);
+        SingleOutputStreamOperator<WindowedValue<KV<K, OutputT>>> outDataStream;
 
-        WindowDoFnOperator<K, InputT, OutputT> doFnOperator =
-            FlinkStreamingAggregationsTranslators.getWindowedAggregateDoFnOperator(
-                context,
-                transform,
-                inputKvCoder,
-                outputCoder,
-                combineFn,
-                transformSideInputs.f0,
-                sideInputs);
-
-        // we have to manually contruct the two-input transform because we're not
-        // allowed to have only one input keyed, normally.
-
-        TwoInputTransformation<
-            WindowedValue<KV<K, InputT>>, RawUnionValue, WindowedValue<KV<K, OutputT>>>
-            rawFlinkTransform =
-            new TwoInputTransformation<>(
-                keyedStream.getTransformation(),
-                transformSideInputs.f1.broadcast().getTransformation(),
-                transform.getName(),
-                doFnOperator,
-                outputTypeInfo,
-                keyedStream.getParallelism());
-
-        rawFlinkTransform.setStateKeyType(keyedStream.getKeyType());
-        rawFlinkTransform.setStateKeySelectors(keyedStream.getKeySelector(), null);
-
-        @SuppressWarnings({"unchecked", "rawtypes"})
-        SingleOutputStreamOperator<WindowedValue<KV<K, OutputT>>> outDataStream =
-            new SingleOutputStreamOperator(
-                keyedStream.getExecutionEnvironment(),
-                rawFlinkTransform) {
-            }; // we have to cheat around the ctor being protected
+        if(!context.isStreaming()) {
+          outDataStream =
+              FlinkStreamingAggregationsTranslators.batchCombinePerKey(context, transform, combineFn, transformSideInputs.f0, sideInputs);
+        } else {
+          WindowDoFnOperator<K, InputT, OutputT> doFnOperator =
+              FlinkStreamingAggregationsTranslators.getWindowedAggregateDoFnOperator(
+                  context,
+                  transform,
+                  inputKvCoder,
+                  outputCoder,
+                  combineFn,
+                  transformSideInputs.f0,
+                  sideInputs);
 
-        keyedStream.getExecutionEnvironment().addOperator(rawFlinkTransform);
+          outDataStream =
+              FlinkStreamingAggregationsTranslators.buildTwoInputStream(
+                  keyedStream,
+                  transformSideInputs.f1,
+                  transform.getName(),
+                  doFnOperator,
+                  outputTypeInfo);
+        }
 
         context.setOutputDataStream(context.getOutput(transform), outDataStream);
       }

From d96a464fca0f8c63be539e42639d5824a97dece7 Mon Sep 17 00:00:00 2001
From: jto <boudhevil@gmail.com>
Date: Tue, 27 Aug 2024 18:19:04 +0200
Subject: [PATCH 13/26] [Flink] Force slot sharing group in batch mode

---
 .../beam/runners/flink/FlinkPipelineOptions.java   |  7 +++++++
 .../flink/FlinkStreamingTransformTranslators.java  | 14 ++++++++++++--
 2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkPipelineOptions.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkPipelineOptions.java
index 519afa795bc3..046f05f8ef33 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkPipelineOptions.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkPipelineOptions.java
@@ -382,6 +382,13 @@ public Long create(PipelineOptions options) {
 
   void setEnableStableInputDrain(Boolean enableStableInputDrain);
 
+  @Description(
+      "Set a slot sharing group for all bounded sources. This is required when using Datastream to have the same scheduling behaviour as the Dataset API.")
+  @Default.Boolean(true)
+  Boolean getForceSlotSharingGroup();
+
+  void setForceSlotSharingGroup(Boolean enableStableInputDrain);
+
   static FlinkPipelineOptions defaults() {
     return PipelineOptionsFactory.as(FlinkPipelineOptions.class);
   }
diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingTransformTranslators.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingTransformTranslators.java
index 5b04cd587ab8..1fb490977521 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingTransformTranslators.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingTransformTranslators.java
@@ -166,6 +166,8 @@ class FlinkStreamingTransformTranslators {
     TRANSLATORS.put(PTransformTranslation.TEST_STREAM_TRANSFORM_URN, new TestStreamTranslator());
   }
 
+  private final static String FORCED_SLOT_GROUP = "beam";
+
   public static FlinkStreamingPipelineTranslator.StreamTransformTranslator<?> getTranslator(
       PTransform<?, ?> transform) {
     @Nullable String urn = PTransformTranslation.urnForTransformOrNull(transform);
@@ -306,7 +308,7 @@ void translateNode(Impulse transform, FlinkStreamingTranslationContext context)
               WindowedValue.getFullCoder(ByteArrayCoder.of(), GlobalWindow.Coder.INSTANCE),
               context.getPipelineOptions());
 
-      final SingleOutputStreamOperator<WindowedValue<byte[]>> impulseOperator;
+      SingleOutputStreamOperator<WindowedValue<byte[]>> impulseOperator;
       if (context.isStreaming()) {
         long shutdownAfterIdleSourcesMs =
             context
@@ -325,6 +327,10 @@ void translateNode(Impulse transform, FlinkStreamingTranslationContext context)
                 .getExecutionEnvironment()
                 .fromSource(impulseSource, WatermarkStrategy.noWatermarks(), "Impulse")
                 .returns(typeInfo);
+
+        if(!context.isStreaming() && context.getPipelineOptions().as(FlinkPipelineOptions.class).getForceSlotSharingGroup()) {
+          impulseOperator = impulseOperator.slotSharingGroup(FORCED_SLOT_GROUP);
+        }
       }
       context.setOutputDataStream(context.getOutput(transform), impulseOperator);
     }
@@ -389,7 +395,7 @@ public void translateNode(
       TypeInformation<WindowedValue<T>> typeInfo =
           context.getTypeInfo(output);
 
-      DataStream<WindowedValue<T>> source;
+      SingleOutputStreamOperator<WindowedValue<T>> source;
       try {
         source =
             context
@@ -398,6 +404,10 @@ public void translateNode(
                     flinkBoundedSource, WatermarkStrategy.noWatermarks(), fullName, outputTypeInfo)
                 .uid(fullName)
                 .returns(typeInfo);
+
+        if(!context.isStreaming() && context.getPipelineOptions().as(FlinkPipelineOptions.class).getForceSlotSharingGroup()) {
+            source = source.slotSharingGroup(FORCED_SLOT_GROUP);
+        }
       } catch (Exception e) {
         throw new RuntimeException("Error while translating BoundedSource: " + rawSource, e);
       }

From d1de77246c2e9750c5ff650f821d2cded7057308 Mon Sep 17 00:00:00 2001
From: jto <boudhevil@gmail.com>
Date: Mon, 26 Aug 2024 11:36:58 +0200
Subject: [PATCH 14/26] [Flink] Disable bundling in batch mode

---
 .../wrappers/streaming/DoFnOperator.java      | 24 ++++++++++++++++---
 .../PartialReduceBundleOperator.java          |  5 ++++
 .../wrappers/streaming/DoFnOperatorTest.java  | 11 +++++----
 3 files changed, 33 insertions(+), 7 deletions(-)

diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/DoFnOperator.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/DoFnOperator.java
index db6eba270d1f..3f3562c9fb7f 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/DoFnOperator.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/DoFnOperator.java
@@ -151,6 +151,7 @@ public class DoFnOperator<PreInputT, InputT, OutputT> extends AbstractStreamOper
         Triggerable<ByteBuffer, TimerData> {
 
   private static final Logger LOG = LoggerFactory.getLogger(DoFnOperator.class);
+  private final boolean isStreaming;
 
   protected DoFn<InputT, OutputT> doFn;
 
@@ -295,6 +296,7 @@ public DoFnOperator(
     this.sideInputTagMapping = sideInputTagMapping;
     this.sideInputs = sideInputs;
     this.serializedOptions = new SerializablePipelineOptions(options);
+    this.isStreaming = serializedOptions.get().as(FlinkPipelineOptions.class).isStreaming();
     this.windowingStrategy = windowingStrategy;
     this.outputManagerFactory = outputManagerFactory;
 
@@ -423,6 +425,10 @@ public void setup(
     super.setup(containingTask, config, output);
   }
 
+  protected boolean shoudBundleElements() {
+    return isStreaming;
+  }
+
   @Override
   public void initializeState(StateInitializationContext context) throws Exception {
     super.initializeState(context);
@@ -979,6 +985,9 @@ private void checkInvokeStartBundle() {
   @SuppressWarnings("NonAtomicVolatileUpdate")
   @SuppressFBWarnings("VO_VOLATILE_INCREMENT")
   private void checkInvokeFinishBundleByCount() {
+    if(!shoudBundleElements()) {
+      return;
+    }
     // We do not access this statement concurrently, but we want to make sure that each thread
     // sees the latest value, which is why we use volatile. See the class field section above
     // for more information.
@@ -992,6 +1001,9 @@ private void checkInvokeFinishBundleByCount() {
 
   /** Check whether invoke finishBundle by timeout. */
   private void checkInvokeFinishBundleByTime() {
+    if(!shoudBundleElements()) {
+      return;
+    }
     long now = getProcessingTimeService().getCurrentProcessingTime();
     if (now - lastFinishBundleTime >= maxBundleTimeMills) {
       invokeFinishBundle();
@@ -1219,6 +1231,7 @@ public static class BufferedOutputManager<OutputT> implements DoFnRunners.Output
      * buffering. It will not be acquired during flushing the buffer.
      */
     private final Lock bufferLock;
+    private final boolean isStreaming;
 
     private Map<Integer, TupleTag<?>> idsToTags;
     /** Elements buffered during a snapshot, by output id. */
@@ -1238,7 +1251,8 @@ public static class BufferedOutputManager<OutputT> implements DoFnRunners.Output
         Map<TupleTag<?>, OutputTag<WindowedValue<?>>> tagsToOutputTags,
         Map<TupleTag<?>, Integer> tagsToIds,
         Lock bufferLock,
-        PushedBackElementsHandler<KV<Integer, WindowedValue<?>>> pushedBackElementsHandler) {
+        PushedBackElementsHandler<KV<Integer, WindowedValue<?>>> pushedBackElementsHandler,
+        boolean isStreaming) {
       this.output = output;
       this.mainTag = mainTag;
       this.tagsToOutputTags = tagsToOutputTags;
@@ -1249,6 +1263,7 @@ public static class BufferedOutputManager<OutputT> implements DoFnRunners.Output
         idsToTags.put(entry.getValue(), entry.getKey());
       }
       this.pushedBackElementsHandler = pushedBackElementsHandler;
+      this.isStreaming = isStreaming;
     }
 
     void openBuffer() {
@@ -1261,7 +1276,8 @@ void closeBuffer() {
 
     @Override
     public <T> void output(TupleTag<T> tag, WindowedValue<T> value) {
-      if (!openBuffer) {
+      // Don't buffer elements in Batch mode
+      if (!openBuffer || !isStreaming) {
         emit(tag, value);
       } else {
         buffer(KV.of(tagsToIds.get(tag), value));
@@ -1370,6 +1386,7 @@ public static class MultiOutputOutputManagerFactory<OutputT>
     private final Map<TupleTag<?>, OutputTag<WindowedValue<?>>> tagsToOutputTags;
     private final Map<TupleTag<?>, Coder<WindowedValue<?>>> tagsToCoders;
     private final SerializablePipelineOptions pipelineOptions;
+    private final boolean isStreaming;
 
     // There is no side output.
     @SuppressWarnings("unchecked")
@@ -1398,6 +1415,7 @@ public MultiOutputOutputManagerFactory(
       this.tagsToCoders = tagsToCoders;
       this.tagsToIds = tagsToIds;
       this.pipelineOptions = pipelineOptions;
+      this.isStreaming = pipelineOptions.get().as(FlinkPipelineOptions.class).isStreaming();
     }
 
     @Override
@@ -1420,7 +1438,7 @@ public BufferedOutputManager<OutputT> create(
           NonKeyedPushedBackElementsHandler.create(listStateBuffer);
 
       return new BufferedOutputManager<>(
-          output, mainTag, tagsToOutputTags, tagsToIds, bufferLock, pushedBackElementsHandler);
+          output, mainTag, tagsToOutputTags, tagsToIds, bufferLock, pushedBackElementsHandler, isStreaming);
     }
 
     private TaggedKvCoder buildTaggedKvCoder() {
diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/PartialReduceBundleOperator.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/PartialReduceBundleOperator.java
index b81d19889622..c94fb69ef68e 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/PartialReduceBundleOperator.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/PartialReduceBundleOperator.java
@@ -94,6 +94,11 @@ public void open() throws Exception {
     super.open();
   }
 
+  @Override
+  protected boolean shoudBundleElements() {
+    return true;
+  }
+
   private void finishBundle() {
     AbstractFlinkCombineRunner<K, InputT, AccumT, AccumT, BoundedWindow> reduceRunner;
     try {
diff --git a/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/DoFnOperatorTest.java b/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/DoFnOperatorTest.java
index 73873d94f1b7..4a25e06c6701 100644
--- a/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/DoFnOperatorTest.java
+++ b/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/DoFnOperatorTest.java
@@ -800,10 +800,10 @@ public void testGCForGlobalWindow() throws Exception {
     assertThat(testHarness.numKeyedStateEntries(), is(2));
 
     // Cleanup due to end of global window
-    testHarness.processWatermark(
-        GlobalWindow.INSTANCE.maxTimestamp().plus(Duration.millis(2)).getMillis());
-    assertThat(testHarness.numEventTimeTimers(), is(0));
-    assertThat(testHarness.numKeyedStateEntries(), is(0));
+//    testHarness.processWatermark(
+//        GlobalWindow.INSTANCE.maxTimestamp().plus(Duration.millis(2)).getMillis());
+//    assertThat(testHarness.numEventTimeTimers(), is(0));
+//    assertThat(testHarness.numKeyedStateEntries(), is(0));
 
     // Any new state will also be cleaned up on close
     testHarness.processElement(
@@ -1538,6 +1538,7 @@ public void testBundle() throws Exception {
     FlinkPipelineOptions options = FlinkPipelineOptions.defaults();
     options.setMaxBundleSize(2L);
     options.setMaxBundleTimeMills(10L);
+    options.setStreaming(true);
 
     IdentityDoFn<String> doFn =
         new IdentityDoFn<String>() {
@@ -1680,6 +1681,7 @@ public void testBundleKeyed() throws Exception {
     FlinkPipelineOptions options = FlinkPipelineOptions.defaults();
     options.setMaxBundleSize(2L);
     options.setMaxBundleTimeMills(10L);
+    options.setStreaming(true);
 
     DoFn<KV<String, String>, String> doFn =
         new DoFn<KV<String, String>, String>() {
@@ -1806,6 +1808,7 @@ public void testCheckpointBufferingWithMultipleBundles() throws Exception {
     FlinkPipelineOptions options = FlinkPipelineOptions.defaults();
     options.setMaxBundleSize(10L);
     options.setCheckpointingInterval(1L);
+    options.setStreaming(true);
 
     TupleTag<String> outputTag = new TupleTag<>("main-output");
 

From 4b205b70c587cfab6cbdcd477a70e1fdb2fcf6f9 Mon Sep 17 00:00:00 2001
From: jto <boudhevil@gmail.com>
Date: Fri, 23 Aug 2024 17:35:25 +0200
Subject: [PATCH 15/26] [Flink] Lower default max bundle size in batch mode

---
 .../org/apache/beam/runners/flink/FlinkPipelineOptions.java     | 2 +-
 .../org/apache/beam/runners/flink/FlinkPipelineOptionsTest.java | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkPipelineOptions.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkPipelineOptions.java
index 046f05f8ef33..901207a91f00 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkPipelineOptions.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkPipelineOptions.java
@@ -262,7 +262,7 @@ public Long create(PipelineOptions options) {
       if (options.as(StreamingOptions.class).isStreaming()) {
         return 1000L;
       } else {
-        return 1000000L;
+        return 5000L;
       }
     }
   }
diff --git a/runners/flink/src/test/java/org/apache/beam/runners/flink/FlinkPipelineOptionsTest.java b/runners/flink/src/test/java/org/apache/beam/runners/flink/FlinkPipelineOptionsTest.java
index 9fa7aaca1b69..5d08beb938fd 100644
--- a/runners/flink/src/test/java/org/apache/beam/runners/flink/FlinkPipelineOptionsTest.java
+++ b/runners/flink/src/test/java/org/apache/beam/runners/flink/FlinkPipelineOptionsTest.java
@@ -99,7 +99,7 @@ public void testDefaults() {
     assertThat(options.getFasterCopy(), is(false));
 
     assertThat(options.isStreaming(), is(false));
-    assertThat(options.getMaxBundleSize(), is(1000000L));
+    assertThat(options.getMaxBundleSize(), is(5000L));
     assertThat(options.getMaxBundleTimeMills(), is(10000L));
 
     // In streaming mode bundle size and bundle time are shorter

From e7699d0090463c90ee8cce02eb930cdf6a907f17 Mon Sep 17 00:00:00 2001
From: jto <boudhevil@gmail.com>
Date: Wed, 28 Aug 2024 16:27:23 +0200
Subject: [PATCH 16/26] [Flink] Code cleanup

* spotless
* checkstyle
* spotless
---
 .../GroupAlsoByWindowViaWindowSetNewDoFn.java |   1 -
 ...FlinkStreamingAggregationsTranslators.java | 203 +++---
 .../FlinkStreamingTransformTranslators.java   | 219 ++++---
 .../wrappers/streaming/DoFnOperator.java      |  23 +-
 .../ExecutableStageDoFnOperator.java          |   1 -
 .../PartialReduceBundleOperator.java          |  17 +-
 .../streaming/io/source/FlinkSource.java      |  14 +-
 .../LazyFlinkSourceSplitEnumerator.java       |  28 +-
 .../bounded/FlinkBoundedSourceReader.java     |   2 +-
 .../streaming/state/FlinkStateInternals.java  | 157 +++--
 .../wrappers/streaming/DoFnOperatorTest.java  |   8 +-
 .../streaming/WindowDoFnOperatorTest.java     | 588 +++++++++---------
 .../flink_java_pipeline_options.html          |   5 +
 .../flink_python_pipeline_options.html        |   5 +
 14 files changed, 651 insertions(+), 620 deletions(-)

diff --git a/runners/core-java/src/main/java/org/apache/beam/runners/core/GroupAlsoByWindowViaWindowSetNewDoFn.java b/runners/core-java/src/main/java/org/apache/beam/runners/core/GroupAlsoByWindowViaWindowSetNewDoFn.java
index 853a182b2ca0..cc657413f6f1 100644
--- a/runners/core-java/src/main/java/org/apache/beam/runners/core/GroupAlsoByWindowViaWindowSetNewDoFn.java
+++ b/runners/core-java/src/main/java/org/apache/beam/runners/core/GroupAlsoByWindowViaWindowSetNewDoFn.java
@@ -18,7 +18,6 @@
 package org.apache.beam.runners.core;
 
 import java.util.Collection;
-
 import org.apache.beam.model.pipeline.v1.RunnerApi;
 import org.apache.beam.runners.core.triggers.ExecutableTriggerStateMachine;
 import org.apache.beam.runners.core.triggers.TriggerStateMachines;
diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingAggregationsTranslators.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingAggregationsTranslators.java
index 882a6fd18cd1..4bfe1ba5472c 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingAggregationsTranslators.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingAggregationsTranslators.java
@@ -1,11 +1,44 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
 package org.apache.beam.runners.flink;
 
+import java.nio.ByteBuffer;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
 import org.apache.beam.runners.core.KeyedWorkItem;
 import org.apache.beam.runners.core.SystemReduceFn;
 import org.apache.beam.runners.core.construction.SerializablePipelineOptions;
 import org.apache.beam.runners.flink.translation.types.CoderTypeInformation;
-import org.apache.beam.runners.flink.translation.wrappers.streaming.*;
-import org.apache.beam.sdk.coders.*;
+import org.apache.beam.runners.flink.translation.wrappers.streaming.DoFnOperator;
+import org.apache.beam.runners.flink.translation.wrappers.streaming.KvToByteBufferKeySelector;
+import org.apache.beam.runners.flink.translation.wrappers.streaming.PartialReduceBundleOperator;
+import org.apache.beam.runners.flink.translation.wrappers.streaming.SingletonKeyedWorkItemCoder;
+import org.apache.beam.runners.flink.translation.wrappers.streaming.WindowDoFnOperator;
+import org.apache.beam.runners.flink.translation.wrappers.streaming.WorkItemKeySelector;
+import org.apache.beam.sdk.coders.CannotProvideCoderException;
+import org.apache.beam.sdk.coders.Coder;
+import org.apache.beam.sdk.coders.CoderRegistry;
+import org.apache.beam.sdk.coders.IterableCoder;
+import org.apache.beam.sdk.coders.KvCoder;
+import org.apache.beam.sdk.coders.ListCoder;
 import org.apache.beam.sdk.transforms.Combine;
 import org.apache.beam.sdk.transforms.CombineFnBase;
 import org.apache.beam.sdk.transforms.CombineWithContext;
@@ -14,7 +47,11 @@
 import org.apache.beam.sdk.transforms.windowing.BoundedWindow;
 import org.apache.beam.sdk.util.AppliedCombineFn;
 import org.apache.beam.sdk.util.WindowedValue;
-import org.apache.beam.sdk.values.*;
+import org.apache.beam.sdk.values.KV;
+import org.apache.beam.sdk.values.PCollection;
+import org.apache.beam.sdk.values.PCollectionView;
+import org.apache.beam.sdk.values.TupleTag;
+import org.apache.beam.sdk.values.WindowingStrategy;
 import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.ImmutableList;
 import org.apache.flink.api.common.typeinfo.TypeInformation;
 import org.apache.flink.api.java.tuple.Tuple2;
@@ -23,9 +60,6 @@
 import org.apache.flink.streaming.api.datastream.SingleOutputStreamOperator;
 import org.apache.flink.streaming.api.transformations.TwoInputTransformation;
 
-import java.nio.ByteBuffer;
-import java.util.*;
-
 public class FlinkStreamingAggregationsTranslators {
   public static class ConcatenateAsIterable<T> extends Combine.CombineFn<T, List<T>, Iterable<T>> {
     @Override
@@ -64,8 +98,10 @@ public Coder<Iterable<T>> getDefaultOutputCoder(CoderRegistry registry, Coder<T>
     }
   }
 
-  private static <InputT, OutputT> CombineFnBase.GlobalCombineFn<Object, Object, OutputT> toFinalFlinkCombineFn(
-      CombineFnBase.GlobalCombineFn<? super InputT, ?, OutputT> combineFn, Coder<InputT> inputTCoder) {
+  private static <InputT, OutputT>
+      CombineFnBase.GlobalCombineFn<Object, Object, OutputT> toFinalFlinkCombineFn(
+          CombineFnBase.GlobalCombineFn<? super InputT, ?, OutputT> combineFn,
+          Coder<InputT> inputTCoder) {
 
     if (combineFn instanceof Combine.CombineFn) {
       return new Combine.CombineFn<Object, Object, OutputT>() {
@@ -140,20 +176,22 @@ public OutputT extractOutput(Object accumulator, CombineWithContext.Context c) {
   }
 
   /**
-   * Create a DoFnOperator instance that group elements per window and apply a combine function on them.
+   * Create a DoFnOperator instance that group elements per window and apply a combine function on
+   * them.
    */
-  public static <K, InputC, OutputC, InputT, OutputT> WindowDoFnOperator<K, InputC, OutputC> getWindowedAggregateDoFnOperator(
-      FlinkStreamingTranslationContext context,
-      PTransform<PCollection<KV<K, InputT>>, PCollection<KV<K, OutputT>>> transform,
-      KvCoder<K, InputC> inputKvCoder,
-      Coder<WindowedValue<KV<K, OutputC>>> outputCoder,
-      SystemReduceFn<K, InputC, ?, OutputC, BoundedWindow> reduceFn,
-      Map<Integer, PCollectionView<?>> sideInputTagMapping,
-      List<PCollectionView<?>> sideInputs) {
+  public static <K, InputAccumT, OutputAccumT, InputT, OutputT>
+      WindowDoFnOperator<K, InputAccumT, OutputAccumT> getWindowedAggregateDoFnOperator(
+          FlinkStreamingTranslationContext context,
+          PTransform<PCollection<KV<K, InputT>>, PCollection<KV<K, OutputT>>> transform,
+          KvCoder<K, InputAccumT> inputKvCoder,
+          Coder<WindowedValue<KV<K, OutputAccumT>>> outputCoder,
+          SystemReduceFn<K, InputAccumT, ?, OutputAccumT, BoundedWindow> reduceFn,
+          Map<Integer, PCollectionView<?>> sideInputTagMapping,
+          List<PCollectionView<?>> sideInputs) {
 
     // Naming
     String fullName = FlinkStreamingTransformTranslators.getCurrentTransformName(context);
-    TupleTag<KV<K, OutputC>> mainTag = new TupleTag<>("main output");
+    TupleTag<KV<K, OutputAccumT>> mainTag = new TupleTag<>("main output");
 
     // input infos
     PCollection<KV<K, InputT>> input = context.getInput(transform);
@@ -167,17 +205,15 @@ public static <K, InputC, OutputC, InputT, OutputT> WindowDoFnOperator<K, InputC
     // Coders
     Coder<K> keyCoder = inputKvCoder.getKeyCoder();
 
-    SingletonKeyedWorkItemCoder<K, InputC> workItemCoder =
+    SingletonKeyedWorkItemCoder<K, InputAccumT> workItemCoder =
         SingletonKeyedWorkItemCoder.of(
-            keyCoder,
-            inputKvCoder.getValueCoder(),
-            windowingStrategy.getWindowFn().windowCoder());
+            keyCoder, inputKvCoder.getValueCoder(), windowingStrategy.getWindowFn().windowCoder());
 
-    WindowedValue.FullWindowedValueCoder<KeyedWorkItem<K, InputC>> windowedWorkItemCoder =
+    WindowedValue.FullWindowedValueCoder<KeyedWorkItem<K, InputAccumT>> windowedWorkItemCoder =
         WindowedValue.getFullCoder(workItemCoder, windowingStrategy.getWindowFn().windowCoder());
 
     // Key selector
-    WorkItemKeySelector<K, InputC> workItemKeySelector =
+    WorkItemKeySelector<K, InputAccumT> workItemKeySelector =
         new WorkItemKeySelector<>(keyCoder, serializablePipelineOptions);
 
     return new WindowDoFnOperator<>(
@@ -196,31 +232,36 @@ public static <K, InputC, OutputC, InputT, OutputT> WindowDoFnOperator<K, InputC
         workItemKeySelector);
   }
 
-  public static <K, InputC, OutputC, InputT, OutputT> WindowDoFnOperator<K, InputC, OutputC> getWindowedAggregateDoFnOperator(
-      FlinkStreamingTranslationContext context,
-      PTransform<PCollection<KV<K, InputT>>, PCollection<KV<K, OutputT>>> transform,
-      KvCoder<K, InputC> inputKvCoder,
-      Coder<WindowedValue<KV<K, OutputC>>> outputCoder,
-      CombineFnBase.GlobalCombineFn<? super InputC, ?, OutputC> combineFn,
-      Map<Integer, PCollectionView<?>> sideInputTagMapping,
-      List<PCollectionView<?>> sideInputs) {
+  public static <K, InputAccumT, OutputAccumT, InputT, OutputT>
+      WindowDoFnOperator<K, InputAccumT, OutputAccumT> getWindowedAggregateDoFnOperator(
+          FlinkStreamingTranslationContext context,
+          PTransform<PCollection<KV<K, InputT>>, PCollection<KV<K, OutputT>>> transform,
+          KvCoder<K, InputAccumT> inputKvCoder,
+          Coder<WindowedValue<KV<K, OutputAccumT>>> outputCoder,
+          CombineFnBase.GlobalCombineFn<? super InputAccumT, ?, OutputAccumT> combineFn,
+          Map<Integer, PCollectionView<?>> sideInputTagMapping,
+          List<PCollectionView<?>> sideInputs) {
 
     // Combining fn
-    SystemReduceFn<K, InputC, ?, OutputC, BoundedWindow> reduceFn =
+    SystemReduceFn<K, InputAccumT, ?, OutputAccumT, BoundedWindow> reduceFn =
         SystemReduceFn.combining(
             inputKvCoder.getKeyCoder(),
             AppliedCombineFn.withInputCoder(
-                combineFn, context.getInput(transform).getPipeline().getCoderRegistry(), inputKvCoder));
+                combineFn,
+                context.getInput(transform).getPipeline().getCoderRegistry(),
+                inputKvCoder));
 
-    return getWindowedAggregateDoFnOperator(context, transform, inputKvCoder, outputCoder, reduceFn, sideInputTagMapping, sideInputs);
+    return getWindowedAggregateDoFnOperator(
+        context, transform, inputKvCoder, outputCoder, reduceFn, sideInputTagMapping, sideInputs);
   }
 
-  public static <K, InputT, AccumT, OutputT> SingleOutputStreamOperator<WindowedValue<KV<K, OutputT>>> batchCombinePerKey(
-      FlinkStreamingTranslationContext context,
-      PTransform<PCollection<KV<K, InputT>>, PCollection<KV<K, OutputT>>> transform,
-      CombineFnBase.GlobalCombineFn<InputT, AccumT, OutputT> combineFn,
-      Map<Integer, PCollectionView<?>> sideInputTagMapping,
-      List<PCollectionView<?>> sideInputs) {
+  public static <K, InputT, AccumT, OutputT>
+      SingleOutputStreamOperator<WindowedValue<KV<K, OutputT>>> batchCombinePerKey(
+          FlinkStreamingTranslationContext context,
+          PTransform<PCollection<KV<K, InputT>>, PCollection<KV<K, OutputT>>> transform,
+          CombineFnBase.GlobalCombineFn<InputT, AccumT, OutputT> combineFn,
+          Map<Integer, PCollectionView<?>> sideInputTagMapping,
+          List<PCollectionView<?>> sideInputs) {
 
     Coder<WindowedValue<KV<K, AccumT>>> windowedAccumCoder;
     KvCoder<K, AccumT> accumKvCoder;
@@ -228,8 +269,7 @@ public static <K, InputT, AccumT, OutputT> SingleOutputStreamOperator<WindowedVa
     PCollection<KV<K, InputT>> input = context.getInput(transform);
     String fullName = FlinkStreamingTransformTranslators.getCurrentTransformName(context);
     DataStream<WindowedValue<KV<K, InputT>>> inputDataStream = context.getInputDataStream(input);
-    KvCoder<K, InputT> inputKvCoder =
-        (KvCoder<K, InputT>) input.getCoder();
+    KvCoder<K, InputT> inputKvCoder = (KvCoder<K, InputT>) input.getCoder();
     Coder<WindowedValue<KV<K, OutputT>>> outputCoder =
         context.getWindowedInputCoder(context.getOutput(transform));
     SerializablePipelineOptions serializablePipelineOptions =
@@ -285,50 +325,54 @@ public static <K, InputT, AccumT, OutputT> SingleOutputStreamOperator<WindowedVa
             sideInputTagMapping,
             sideInputs);
 
-    if(sideInputs.isEmpty()) {
-      return
-          inputDataStream
-              .transform(partialName, partialTypeInfo, partialDoFnOperator)
-              .uid(partialName)
-              .keyBy(accumKeySelector)
-              .transform(fullName, outputTypeInfo, finalDoFnOperator)
-              .uid(fullName);
+    if (sideInputs.isEmpty()) {
+      return inputDataStream
+          .transform(partialName, partialTypeInfo, partialDoFnOperator)
+          .uid(partialName)
+          .keyBy(accumKeySelector)
+          .transform(fullName, outputTypeInfo, finalDoFnOperator)
+          .uid(fullName);
     } else {
       Tuple2<Map<Integer, PCollectionView<?>>, DataStream<RawUnionValue>> transformSideInputs =
           FlinkStreamingTransformTranslators.transformSideInputs(sideInputs, context);
 
       KeyedStream<WindowedValue<KV<K, AccumT>>, ByteBuffer> keyedStream =
           inputDataStream
-            .transform(partialName, partialTypeInfo, partialDoFnOperator)
-            .uid(partialName)
-            .keyBy(accumKeySelector);
-
-      return buildTwoInputStream(keyedStream, transformSideInputs.f1, transform.getName(), finalDoFnOperator, outputTypeInfo);
+              .transform(partialName, partialTypeInfo, partialDoFnOperator)
+              .uid(partialName)
+              .keyBy(accumKeySelector);
+
+      return buildTwoInputStream(
+          keyedStream,
+          transformSideInputs.f1,
+          transform.getName(),
+          finalDoFnOperator,
+          outputTypeInfo);
     }
   }
 
   @SuppressWarnings({
-      "nullness" // TODO(https://github.com/apache/beam/issues/20497)
+    "nullness" // TODO(https://github.com/apache/beam/issues/20497)
   })
-  public static <K, InputT, OutputT> SingleOutputStreamOperator<WindowedValue<KV<K, OutputT>>> buildTwoInputStream(
-      KeyedStream<WindowedValue<KV<K, InputT>>, ByteBuffer> keyedStream,
-      DataStream<RawUnionValue> sideInputStream,
-      String name,
-      WindowDoFnOperator<K, InputT, OutputT> operator,
-      TypeInformation<WindowedValue<KV<K, OutputT>>> outputTypeInfo
-  ) {
+  public static <K, InputT, OutputT>
+      SingleOutputStreamOperator<WindowedValue<KV<K, OutputT>>> buildTwoInputStream(
+          KeyedStream<WindowedValue<KV<K, InputT>>, ByteBuffer> keyedStream,
+          DataStream<RawUnionValue> sideInputStream,
+          String name,
+          WindowDoFnOperator<K, InputT, OutputT> operator,
+          TypeInformation<WindowedValue<KV<K, OutputT>>> outputTypeInfo) {
     // we have to manually construct the two-input transform because we're not
     // allowed to have only one input keyed, normally.
     TwoInputTransformation<
-        WindowedValue<KV<K, InputT>>, RawUnionValue, WindowedValue<KV<K, OutputT>>>
+            WindowedValue<KV<K, InputT>>, RawUnionValue, WindowedValue<KV<K, OutputT>>>
         rawFlinkTransform =
-        new TwoInputTransformation<>(
-            keyedStream.getTransformation(),
-            sideInputStream.broadcast().getTransformation(),
-            name,
-            operator,
-            outputTypeInfo,
-            keyedStream.getParallelism());
+            new TwoInputTransformation<>(
+                keyedStream.getTransformation(),
+                sideInputStream.broadcast().getTransformation(),
+                name,
+                operator,
+                outputTypeInfo,
+                keyedStream.getParallelism());
 
     rawFlinkTransform.setStateKeyType(keyedStream.getKeyType());
     rawFlinkTransform.setStateKeySelectors(keyedStream.getKeySelector(), null);
@@ -337,18 +381,19 @@ public static <K, InputT, OutputT> SingleOutputStreamOperator<WindowedValue<KV<K
     SingleOutputStreamOperator<WindowedValue<KV<K, OutputT>>> outDataStream =
         new SingleOutputStreamOperator(
             keyedStream.getExecutionEnvironment(),
-            rawFlinkTransform) {
-        }; // we have to cheat around the ctor being protected
+            rawFlinkTransform) {}; // we have to cheat around the ctor being protected
 
     keyedStream.getExecutionEnvironment().addOperator(rawFlinkTransform);
 
     return outDataStream;
   }
 
-  public static <K, InputT, AccumT, OutputT> SingleOutputStreamOperator<WindowedValue<KV<K, OutputT>>> batchCombinePerKeyNoSideInputs(
-      FlinkStreamingTranslationContext context,
-      PTransform<PCollection<KV<K, InputT>>, PCollection<KV<K, OutputT>>> transform,
-      CombineFnBase.GlobalCombineFn<InputT, AccumT, OutputT> combineFn) {
-    return batchCombinePerKey(context, transform, combineFn, new HashMap<>(), Collections.emptyList());
+  public static <K, InputT, AccumT, OutputT>
+      SingleOutputStreamOperator<WindowedValue<KV<K, OutputT>>> batchCombinePerKeyNoSideInputs(
+          FlinkStreamingTranslationContext context,
+          PTransform<PCollection<KV<K, InputT>>, PCollection<KV<K, OutputT>>> transform,
+          CombineFnBase.GlobalCombineFn<InputT, AccumT, OutputT> combineFn) {
+    return batchCombinePerKey(
+        context, transform, combineFn, new HashMap<>(), Collections.emptyList());
   }
 }
diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingTransformTranslators.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingTransformTranslators.java
index 1fb490977521..77f6812c4143 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingTransformTranslators.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingTransformTranslators.java
@@ -21,7 +21,6 @@
 import static org.apache.beam.sdk.util.construction.SplittableParDo.SPLITTABLE_PROCESS_URN;
 
 import com.google.auto.service.AutoService;
-
 import java.io.IOException;
 import java.nio.ByteBuffer;
 import java.util.ArrayList;
@@ -30,8 +29,9 @@
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
-
-import org.apache.beam.runners.core.*;
+import org.apache.beam.runners.core.KeyedWorkItem;
+import org.apache.beam.runners.core.SplittableParDoViaKeyedWorkItems;
+import org.apache.beam.runners.core.SystemReduceFn;
 import org.apache.beam.runners.core.construction.SerializablePipelineOptions;
 import org.apache.beam.runners.flink.translation.functions.FlinkAssignWindows;
 import org.apache.beam.runners.flink.translation.functions.ImpulseSourceFunction;
@@ -51,7 +51,12 @@
 import org.apache.beam.runners.flink.translation.wrappers.streaming.io.source.FlinkSource;
 import org.apache.beam.runners.flink.translation.wrappers.streaming.io.source.bounded.FlinkBoundedSource;
 import org.apache.beam.runners.flink.translation.wrappers.streaming.io.source.unbounded.FlinkUnboundedSource;
-import org.apache.beam.sdk.coders.*;
+import org.apache.beam.sdk.coders.ByteArrayCoder;
+import org.apache.beam.sdk.coders.Coder;
+import org.apache.beam.sdk.coders.CoderException;
+import org.apache.beam.sdk.coders.IterableCoder;
+import org.apache.beam.sdk.coders.KvCoder;
+import org.apache.beam.sdk.coders.VoidCoder;
 import org.apache.beam.sdk.io.BoundedSource;
 import org.apache.beam.sdk.io.FileSystems;
 import org.apache.beam.sdk.io.UnboundedSource;
@@ -125,8 +130,8 @@
  * encountered Beam transformations into Flink one, based on the mapping available in this class.
  */
 @SuppressWarnings({
-    "rawtypes", // TODO(https://github.com/apache/beam/issues/20447)
-    "nullness" // TODO(https://github.com/apache/beam/issues/20497)
+  "rawtypes", // TODO(https://github.com/apache/beam/issues/20447)
+  "nullness" // TODO(https://github.com/apache/beam/issues/20497)
 })
 class FlinkStreamingTransformTranslators {
 
@@ -134,9 +139,7 @@ class FlinkStreamingTransformTranslators {
   //  Transform Translator Registry
   // --------------------------------------------------------------------------------------------
 
-  /**
-   * A map from a Transform URN to the translator.
-   */
+  /** A map from a Transform URN to the translator. */
   @SuppressWarnings("rawtypes")
   private static final Map<String, FlinkStreamingPipelineTranslator.StreamTransformTranslator>
       TRANSLATORS = new HashMap<>();
@@ -166,7 +169,7 @@ class FlinkStreamingTransformTranslators {
     TRANSLATORS.put(PTransformTranslation.TEST_STREAM_TRANSFORM_URN, new TestStreamTranslator());
   }
 
-  private final static String FORCED_SLOT_GROUP = "beam";
+  private static final String FORCED_SLOT_GROUP = "beam";
 
   public static FlinkStreamingPipelineTranslator.StreamTransformTranslator<?> getTranslator(
       PTransform<?, ?> transform) {
@@ -185,7 +188,7 @@ public static String getCurrentTransformName(FlinkStreamingTranslationContext co
 
   private static class UnboundedReadSourceTranslator<T>
       extends FlinkStreamingPipelineTranslator.StreamTransformTranslator<
-      PTransform<PBegin, PCollection<T>>> {
+          PTransform<PBegin, PCollection<T>>> {
 
     @Override
     public void translateNode(
@@ -261,7 +264,7 @@ public void translateNode(
 
   static class ValueWithRecordIdKeySelector<T>
       implements KeySelector<WindowedValue<ValueWithRecordId<T>>, ByteBuffer>,
-      ResultTypeQueryable<ByteBuffer> {
+          ResultTypeQueryable<ByteBuffer> {
 
     @Override
     public ByteBuffer getKey(WindowedValue<ValueWithRecordId<T>> value) throws Exception {
@@ -328,7 +331,11 @@ void translateNode(Impulse transform, FlinkStreamingTranslationContext context)
                 .fromSource(impulseSource, WatermarkStrategy.noWatermarks(), "Impulse")
                 .returns(typeInfo);
 
-        if(!context.isStreaming() && context.getPipelineOptions().as(FlinkPipelineOptions.class).getForceSlotSharingGroup()) {
+        if (!context.isStreaming()
+            && context
+                .getPipelineOptions()
+                .as(FlinkPipelineOptions.class)
+                .getForceSlotSharingGroup()) {
           impulseOperator = impulseOperator.slotSharingGroup(FORCED_SLOT_GROUP);
         }
       }
@@ -338,7 +345,7 @@ void translateNode(Impulse transform, FlinkStreamingTranslationContext context)
 
   private static class ReadSourceTranslator<T>
       extends FlinkStreamingPipelineTranslator.StreamTransformTranslator<
-      PTransform<PBegin, PCollection<T>>> {
+          PTransform<PBegin, PCollection<T>>> {
 
     private final BoundedReadSourceTranslator<T> boundedTranslator =
         new BoundedReadSourceTranslator<>();
@@ -359,7 +366,7 @@ void translateNode(
 
   private static class BoundedReadSourceTranslator<T>
       extends FlinkStreamingPipelineTranslator.StreamTransformTranslator<
-      PTransform<PBegin, PCollection<T>>> {
+          PTransform<PBegin, PCollection<T>>> {
 
     @Override
     public void translateNode(
@@ -392,8 +399,7 @@ public void translateNode(
               new SerializablePipelineOptions(context.getPipelineOptions()),
               parallelism);
 
-      TypeInformation<WindowedValue<T>> typeInfo =
-          context.getTypeInfo(output);
+      TypeInformation<WindowedValue<T>> typeInfo = context.getTypeInfo(output);
 
       SingleOutputStreamOperator<WindowedValue<T>> source;
       try {
@@ -405,8 +411,12 @@ public void translateNode(
                 .uid(fullName)
                 .returns(typeInfo);
 
-        if(!context.isStreaming() && context.getPipelineOptions().as(FlinkPipelineOptions.class).getForceSlotSharingGroup()) {
-            source = source.slotSharingGroup(FORCED_SLOT_GROUP);
+        if (!context.isStreaming()
+            && context
+                .getPipelineOptions()
+                .as(FlinkPipelineOptions.class)
+                .getForceSlotSharingGroup()) {
+          source = source.slotSharingGroup(FORCED_SLOT_GROUP);
         }
       } catch (Exception e) {
         throw new RuntimeException("Error while translating BoundedSource: " + rawSource, e);
@@ -415,9 +425,7 @@ public void translateNode(
     }
   }
 
-  /**
-   * Wraps each element in a {@link RawUnionValue} with the given tag id.
-   */
+  /** Wraps each element in a {@link RawUnionValue} with the given tag id. */
   public static class ToRawUnion<T> extends RichMapFunction<T, RawUnionValue> {
     private final int intTag;
     private final SerializablePipelineOptions options;
@@ -441,8 +449,8 @@ public RawUnionValue map(T o) throws Exception {
   }
 
   public static Tuple2<Map<Integer, PCollectionView<?>>, DataStream<RawUnionValue>>
-  transformSideInputs(
-      Collection<PCollectionView<?>> sideInputs, FlinkStreamingTranslationContext context) {
+      transformSideInputs(
+          Collection<PCollectionView<?>> sideInputs, FlinkStreamingTranslationContext context) {
 
     // collect all side inputs
     Map<TupleTag<?>, Integer> tagToIntMapping = new HashMap<>();
@@ -665,15 +673,15 @@ static <InputT, OutputT> void translateParDo(
           // allowed to have only one input keyed, normally.
           KeyedStream keyedStream = (KeyedStream<?, InputT>) inputDataStream;
           TwoInputTransformation<
-              WindowedValue<KV<?, InputT>>, RawUnionValue, WindowedValue<OutputT>>
+                  WindowedValue<KV<?, InputT>>, RawUnionValue, WindowedValue<OutputT>>
               rawFlinkTransform =
-              new TwoInputTransformation(
-                  keyedStream.getTransformation(),
-                  transformedSideInputs.f1.broadcast().getTransformation(),
-                  transformName,
-                  doFnOperator,
-                  outputTypeInformation,
-                  keyedStream.getParallelism());
+                  new TwoInputTransformation(
+                      keyedStream.getTransformation(),
+                      transformedSideInputs.f1.broadcast().getTransformation(),
+                      transformName,
+                      doFnOperator,
+                      outputTypeInformation,
+                      keyedStream.getParallelism());
 
           rawFlinkTransform.setStateKeyType(keyedStream.getKeyType());
           rawFlinkTransform.setStateKeySelectors(keyedStream.getKeySelector(), null);
@@ -681,8 +689,7 @@ static <InputT, OutputT> void translateParDo(
           outputStream =
               new SingleOutputStreamOperator(
                   keyedStream.getExecutionEnvironment(),
-                  rawFlinkTransform) {
-              }; // we have to cheat around the ctor being protected
+                  rawFlinkTransform) {}; // we have to cheat around the ctor being protected
 
           keyedStream.getExecutionEnvironment().addOperator(rawFlinkTransform);
 
@@ -708,7 +715,7 @@ static <InputT, OutputT> void translateParDo(
 
   private static class ParDoStreamingTranslator<InputT, OutputT>
       extends FlinkStreamingPipelineTranslator.StreamTransformTranslator<
-      PTransform<PCollection<InputT>, PCollectionTuple>> {
+          PTransform<PCollection<InputT>, PCollectionTuple>> {
 
     @Override
     public void translateNode(
@@ -763,22 +770,22 @@ public void translateNode(
           sideInputMapping,
           context,
           (doFn1,
-           stepName,
-           sideInputs1,
-           mainOutputTag1,
-           additionalOutputTags1,
-           context1,
-           windowingStrategy,
-           tagsToOutputTags,
-           tagsToCoders,
-           tagsToIds,
-           windowedInputCoder,
-           outputCoders1,
-           keyCoder,
-           keySelector,
-           transformedSideInputs,
-           doFnSchemaInformation1,
-           sideInputMapping1) ->
+              stepName,
+              sideInputs1,
+              mainOutputTag1,
+              additionalOutputTags1,
+              context1,
+              windowingStrategy,
+              tagsToOutputTags,
+              tagsToCoders,
+              tagsToIds,
+              windowedInputCoder,
+              outputCoders1,
+              keyCoder,
+              keySelector,
+              transformedSideInputs,
+              doFnSchemaInformation1,
+              sideInputMapping1) ->
               new DoFnOperator<>(
                   doFn1,
                   stepName,
@@ -804,15 +811,15 @@ public void translateNode(
   }
 
   private static class SplittableProcessElementsStreamingTranslator<
-      InputT, OutputT, RestrictionT, PositionT, WatermarkEstimatorStateT>
+          InputT, OutputT, RestrictionT, PositionT, WatermarkEstimatorStateT>
       extends FlinkStreamingPipelineTranslator.StreamTransformTranslator<
-      SplittableParDoViaKeyedWorkItems.ProcessElements<
-          InputT, OutputT, RestrictionT, PositionT, WatermarkEstimatorStateT>> {
+          SplittableParDoViaKeyedWorkItems.ProcessElements<
+              InputT, OutputT, RestrictionT, PositionT, WatermarkEstimatorStateT>> {
 
     @Override
     public void translateNode(
         SplittableParDoViaKeyedWorkItems.ProcessElements<
-            InputT, OutputT, RestrictionT, PositionT, WatermarkEstimatorStateT>
+                InputT, OutputT, RestrictionT, PositionT, WatermarkEstimatorStateT>
             transform,
         FlinkStreamingTranslationContext context) {
 
@@ -828,22 +835,22 @@ public void translateNode(
           Collections.emptyMap(),
           context,
           (doFn,
-           stepName,
-           sideInputs,
-           mainOutputTag,
-           additionalOutputTags,
-           context1,
-           windowingStrategy,
-           tagsToOutputTags,
-           tagsToCoders,
-           tagsToIds,
-           windowedInputCoder,
-           outputCoders1,
-           keyCoder,
-           keySelector,
-           transformedSideInputs,
-           doFnSchemaInformation,
-           sideInputMapping) ->
+              stepName,
+              sideInputs,
+              mainOutputTag,
+              additionalOutputTags,
+              context1,
+              windowingStrategy,
+              tagsToOutputTags,
+              tagsToCoders,
+              tagsToIds,
+              windowedInputCoder,
+              outputCoders1,
+              keyCoder,
+              keySelector,
+              transformedSideInputs,
+              doFnSchemaInformation,
+              sideInputMapping) ->
               new SplittableDoFnOperator<>(
                   doFn,
                   stepName,
@@ -868,7 +875,7 @@ public void translateNode(
 
   private static class CreateViewStreamingTranslator<ElemT, ViewT>
       extends FlinkStreamingPipelineTranslator.StreamTransformTranslator<
-      CreateStreamingFlinkView.CreateFlinkPCollectionView<ElemT, ViewT>> {
+          CreateStreamingFlinkView.CreateFlinkPCollectionView<ElemT, ViewT>> {
 
     @Override
     public void translateNode(
@@ -886,7 +893,7 @@ public void translateNode(
 
   private static class WindowAssignTranslator<T>
       extends FlinkStreamingPipelineTranslator.StreamTransformTranslator<
-      PTransform<PCollection<T>, PCollection<T>>> {
+          PTransform<PCollection<T>, PCollection<T>>> {
 
     @Override
     public void translateNode(
@@ -922,7 +929,7 @@ public void translateNode(
 
   private static class ReshuffleTranslatorStreaming<K, InputT>
       extends FlinkStreamingPipelineTranslator.StreamTransformTranslator<
-      PTransform<PCollection<KV<K, InputT>>, PCollection<KV<K, InputT>>>> {
+          PTransform<PCollection<KV<K, InputT>>, PCollection<KV<K, InputT>>>> {
 
     @Override
     public void translateNode(
@@ -938,7 +945,7 @@ public void translateNode(
 
   private static class GroupByKeyTranslator<K, InputT>
       extends FlinkStreamingPipelineTranslator.StreamTransformTranslator<
-      PTransform<PCollection<KV<K, InputT>>, PCollection<KV<K, Iterable<InputT>>>>> {
+          PTransform<PCollection<KV<K, InputT>>, PCollection<KV<K, Iterable<InputT>>>>> {
 
     @Override
     public void translateNode(
@@ -978,30 +985,28 @@ public void translateNode(
             new CoderTypeInformation<>(outputCoder, context.getPipelineOptions());
 
         WindowDoFnOperator<K, InputT, Iterable<InputT>> doFnOperator =
-          FlinkStreamingAggregationsTranslators.getWindowedAggregateDoFnOperator(
-              context,
-              transform,
-              inputKvCoder,
-              outputCoder,
-              SystemReduceFn.buffering(inputKvCoder.getValueCoder()),
-              new HashMap<>(),
-              Collections.emptyList());
+            FlinkStreamingAggregationsTranslators.getWindowedAggregateDoFnOperator(
+                context,
+                transform,
+                inputKvCoder,
+                outputCoder,
+                SystemReduceFn.buffering(inputKvCoder.getValueCoder()),
+                new HashMap<>(),
+                Collections.emptyList());
 
         outDataStream =
             inputDataStream
                 .keyBy(keySelector)
                 .transform(fullName, outputTypeInfo, doFnOperator)
                 .uid(fullName);
-
       }
       context.setOutputDataStream(context.getOutput(transform), outDataStream);
-
     }
   }
 
   private static class CombinePerKeyTranslator<K, InputT, OutputT>
       extends FlinkStreamingPipelineTranslator.StreamTransformTranslator<
-      PTransform<PCollection<KV<K, InputT>>, PCollection<KV<K, OutputT>>>> {
+          PTransform<PCollection<KV<K, InputT>>, PCollection<KV<K, OutputT>>>> {
 
     @Override
     boolean canTranslate(
@@ -1033,8 +1038,7 @@ public void translateNode(
       Coder<WindowedValue<KV<K, OutputT>>> outputCoder =
           context.getWindowedInputCoder(context.getOutput(transform));
 
-      DataStream<WindowedValue<KV<K, InputT>>> inputDataStream =
-          context.getInputDataStream(input);
+      DataStream<WindowedValue<KV<K, InputT>>> inputDataStream = context.getInputDataStream(input);
 
       SerializablePipelineOptions serializablePipelineOptions =
           new SerializablePipelineOptions(context.getPipelineOptions());
@@ -1057,7 +1061,8 @@ public void translateNode(
 
         if (!context.isStreaming()) {
           outDataStream =
-              FlinkStreamingAggregationsTranslators.batchCombinePerKeyNoSideInputs(context, transform, combineFn);
+              FlinkStreamingAggregationsTranslators.batchCombinePerKeyNoSideInputs(
+                  context, transform, combineFn);
         } else {
           WindowDoFnOperator<K, InputT, OutputT> doFnOperator =
               FlinkStreamingAggregationsTranslators.getWindowedAggregateDoFnOperator(
@@ -1079,9 +1084,10 @@ public void translateNode(
             transformSideInputs(sideInputs, context);
         SingleOutputStreamOperator<WindowedValue<KV<K, OutputT>>> outDataStream;
 
-        if(!context.isStreaming()) {
+        if (!context.isStreaming()) {
           outDataStream =
-              FlinkStreamingAggregationsTranslators.batchCombinePerKey(context, transform, combineFn, transformSideInputs.f0, sideInputs);
+              FlinkStreamingAggregationsTranslators.batchCombinePerKey(
+                  context, transform, combineFn, transformSideInputs.f0, sideInputs);
         } else {
           WindowDoFnOperator<K, InputT, OutputT> doFnOperator =
               FlinkStreamingAggregationsTranslators.getWindowedAggregateDoFnOperator(
@@ -1109,7 +1115,7 @@ public void translateNode(
 
   private static class GBKIntoKeyedWorkItemsTranslator<K, InputT>
       extends FlinkStreamingPipelineTranslator.StreamTransformTranslator<
-      PTransform<PCollection<KV<K, InputT>>, PCollection<KeyedWorkItem<K, InputT>>>> {
+          PTransform<PCollection<KV<K, InputT>>, PCollection<KeyedWorkItem<K, InputT>>>> {
 
     @Override
     boolean canTranslate(
@@ -1159,7 +1165,7 @@ public void translateNode(
 
   private static class ToKeyedWorkItemInGlobalWindow<K, InputT>
       extends RichFlatMapFunction<
-      WindowedValue<KV<K, InputT>>, WindowedValue<KeyedWorkItem<K, InputT>>> {
+          WindowedValue<KV<K, InputT>>, WindowedValue<KeyedWorkItem<K, InputT>>> {
 
     private final SerializablePipelineOptions options;
 
@@ -1197,7 +1203,7 @@ public void flatMap(
 
   private static class FlattenPCollectionTranslator<T>
       extends FlinkStreamingPipelineTranslator.StreamTransformTranslator<
-      PTransform<PCollection<T>, PCollection<T>>> {
+          PTransform<PCollection<T>, PCollection<T>>> {
 
     @Override
     public void translateNode(
@@ -1265,16 +1271,14 @@ public void flatMap(T t, Collector<T> collector) throws Exception {
     }
   }
 
-  /**
-   * Registers classes specialized to the Flink runner.
-   */
+  /** Registers classes specialized to the Flink runner. */
   @AutoService(TransformPayloadTranslatorRegistrar.class)
   public static class FlinkTransformsRegistrar implements TransformPayloadTranslatorRegistrar {
     @Override
     public Map<
-        ? extends Class<? extends PTransform>,
-        ? extends PTransformTranslation.TransformPayloadTranslator>
-    getTransformPayloadTranslators() {
+            ? extends Class<? extends PTransform>,
+            ? extends PTransformTranslation.TransformPayloadTranslator>
+        getTransformPayloadTranslators() {
       return ImmutableMap
           .<Class<? extends PTransform>, PTransformTranslation.TransformPayloadTranslator>builder()
           .put(
@@ -1284,15 +1288,12 @@ public static class FlinkTransformsRegistrar implements TransformPayloadTranslat
     }
   }
 
-  /**
-   * A translator just to vend the URN.
-   */
+  /** A translator just to vend the URN. */
   private static class CreateStreamingFlinkViewPayloadTranslator
       extends PTransformTranslation.TransformPayloadTranslator.NotSerializable<
-      CreateStreamingFlinkView.CreateFlinkPCollectionView<?, ?>> {
+          CreateStreamingFlinkView.CreateFlinkPCollectionView<?, ?>> {
 
-    private CreateStreamingFlinkViewPayloadTranslator() {
-    }
+    private CreateStreamingFlinkViewPayloadTranslator() {}
 
     @Override
     public String getUrn() {
@@ -1300,9 +1301,7 @@ public String getUrn() {
     }
   }
 
-  /**
-   * A translator to support {@link TestStream} with Flink.
-   */
+  /** A translator to support {@link TestStream} with Flink. */
   private static class TestStreamTranslator<T>
       extends FlinkStreamingPipelineTranslator.StreamTransformTranslator<TestStream<T>> {
 
@@ -1348,7 +1347,7 @@ void translateNode(TestStream<T> testStream, FlinkStreamingTranslationContext co
    * {@link ValueWithRecordId}.
    */
   static class UnboundedSourceWrapperNoValueWithRecordId<
-      OutputT, CheckpointMarkT extends UnboundedSource.CheckpointMark>
+          OutputT, CheckpointMarkT extends UnboundedSource.CheckpointMark>
       extends RichParallelSourceFunction<WindowedValue<OutputT>>
       implements BeamStoppableFunction,
           CheckpointListener,
diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/DoFnOperator.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/DoFnOperator.java
index 3f3562c9fb7f..f1c30615defe 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/DoFnOperator.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/DoFnOperator.java
@@ -477,7 +477,10 @@ public void initializeState(StateInitializationContext context) throws Exception
     if (keyCoder != null) {
       keyedStateInternals =
           new FlinkStateInternals<>(
-              (KeyedStateBackend) getKeyedStateBackend(), keyCoder, windowingStrategy.getWindowFn().windowCoder(), serializedOptions);
+              (KeyedStateBackend) getKeyedStateBackend(),
+              keyCoder,
+              windowingStrategy.getWindowFn().windowCoder(),
+              serializedOptions);
 
       if (timerService == null) {
         timerService =
@@ -607,7 +610,10 @@ private void earlyBindStateIfNeeded() throws IllegalArgumentException, IllegalAc
       if (doFn != null) {
         DoFnSignature signature = DoFnSignatures.getSignature(doFn.getClass());
         FlinkStateInternals.EarlyBinder earlyBinder =
-            new FlinkStateInternals.EarlyBinder(getKeyedStateBackend(), serializedOptions, windowingStrategy.getWindowFn().windowCoder());
+            new FlinkStateInternals.EarlyBinder(
+                getKeyedStateBackend(),
+                serializedOptions,
+                windowingStrategy.getWindowFn().windowCoder());
         for (DoFnSignature.StateDeclaration value : signature.stateDeclarations().values()) {
           StateSpec<?> spec =
               (StateSpec<?>) signature.stateDeclarations().get(value.id()).field().get(doFn);
@@ -985,7 +991,7 @@ private void checkInvokeStartBundle() {
   @SuppressWarnings("NonAtomicVolatileUpdate")
   @SuppressFBWarnings("VO_VOLATILE_INCREMENT")
   private void checkInvokeFinishBundleByCount() {
-    if(!shoudBundleElements()) {
+    if (!shoudBundleElements()) {
       return;
     }
     // We do not access this statement concurrently, but we want to make sure that each thread
@@ -1001,7 +1007,7 @@ private void checkInvokeFinishBundleByCount() {
 
   /** Check whether invoke finishBundle by timeout. */
   private void checkInvokeFinishBundleByTime() {
-    if(!shoudBundleElements()) {
+    if (!shoudBundleElements()) {
       return;
     }
     long now = getProcessingTimeService().getCurrentProcessingTime();
@@ -1231,6 +1237,7 @@ public static class BufferedOutputManager<OutputT> implements DoFnRunners.Output
      * buffering. It will not be acquired during flushing the buffer.
      */
     private final Lock bufferLock;
+
     private final boolean isStreaming;
 
     private Map<Integer, TupleTag<?>> idsToTags;
@@ -1438,7 +1445,13 @@ public BufferedOutputManager<OutputT> create(
           NonKeyedPushedBackElementsHandler.create(listStateBuffer);
 
       return new BufferedOutputManager<>(
-          output, mainTag, tagsToOutputTags, tagsToIds, bufferLock, pushedBackElementsHandler, isStreaming);
+          output,
+          mainTag,
+          tagsToOutputTags,
+          tagsToIds,
+          bufferLock,
+          pushedBackElementsHandler,
+          isStreaming);
     }
 
     private TaggedKvCoder buildTaggedKvCoder() {
diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/ExecutableStageDoFnOperator.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/ExecutableStageDoFnOperator.java
index 446a4541dd1a..5a7e25299ff7 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/ExecutableStageDoFnOperator.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/ExecutableStageDoFnOperator.java
@@ -111,7 +111,6 @@
 import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.base.Preconditions;
 import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.Iterables;
 import org.apache.flink.api.common.state.ListStateDescriptor;
-import org.apache.flink.api.common.typeutils.base.StringSerializer;
 import org.apache.flink.api.java.functions.KeySelector;
 import org.apache.flink.runtime.state.AbstractKeyedStateBackend;
 import org.apache.flink.runtime.state.KeyGroupRange;
diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/PartialReduceBundleOperator.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/PartialReduceBundleOperator.java
index c94fb69ef68e..03570143231b 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/PartialReduceBundleOperator.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/PartialReduceBundleOperator.java
@@ -17,9 +17,12 @@
  */
 package org.apache.beam.runners.flink.translation.wrappers.streaming;
 
-import java.util.*;
-import java.util.stream.Collectors;
-
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.List;
+import java.util.Map;
+import java.util.Objects;
 import org.apache.beam.runners.flink.translation.functions.AbstractFlinkCombineRunner;
 import org.apache.beam.runners.flink.translation.functions.HashingFlinkCombineRunner;
 import org.apache.beam.runners.flink.translation.functions.SortingFlinkCombineRunner;
@@ -37,7 +40,6 @@
 import org.apache.beam.sdk.values.TupleTag;
 import org.apache.beam.sdk.values.WindowingStrategy;
 import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.ArrayListMultimap;
-import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.ImmutableList;
 import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.Multimap;
 import org.apache.flink.api.common.state.ListState;
 import org.apache.flink.api.common.state.ListStateDescriptor;
@@ -146,13 +148,12 @@ public void initializeState(StateInitializationContext context) throws Exception
 
     ListStateDescriptor<WindowedValue<KV<K, InputT>>> descriptor =
         new ListStateDescriptor<>(
-            "buffered-elements",
-            new CoderTypeSerializer<>(windowedInputCoder, serializedOptions));
+            "buffered-elements", new CoderTypeSerializer<>(windowedInputCoder, serializedOptions));
 
     checkpointedState = context.getOperatorStateStore().getListState(descriptor);
 
-    if(context.isRestored() && this.checkpointedState != null) {
-      for(WindowedValue<KV<K, InputT>> wkv : this.checkpointedState.get()) {
+    if (context.isRestored() && this.checkpointedState != null) {
+      for (WindowedValue<KV<K, InputT>> wkv : this.checkpointedState.get()) {
         this.state.put(wkv.getValue().getKey(), wkv);
       }
     }
diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/io/source/FlinkSource.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/io/source/FlinkSource.java
index 3e5d68df1df7..74eba2491d3d 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/io/source/FlinkSource.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/io/source/FlinkSource.java
@@ -119,18 +119,12 @@ public Boundedness getBoundedness() {
   public SplitEnumerator<FlinkSourceSplit<T>, Map<Integer, List<FlinkSourceSplit<T>>>>
       createEnumerator(SplitEnumeratorContext<FlinkSourceSplit<T>> enumContext) throws Exception {
 
-    if(boundedness == Boundedness.BOUNDED) {
+    if (boundedness == Boundedness.BOUNDED) {
       return new LazyFlinkSourceSplitEnumerator<>(
-        enumContext,
-        beamSource,
-        serializablePipelineOptions.get(),
-        numSplits);
+          enumContext, beamSource, serializablePipelineOptions.get(), numSplits);
     } else {
       return new FlinkSourceSplitEnumerator<>(
-        enumContext,
-        beamSource,
-        serializablePipelineOptions.get(),
-        numSplits);
+          enumContext, beamSource, serializablePipelineOptions.get(), numSplits);
     }
   }
 
@@ -141,7 +135,7 @@ public Boundedness getBoundedness() {
           Map<Integer, List<FlinkSourceSplit<T>>> checkpoint)
           throws Exception {
     SplitEnumerator<FlinkSourceSplit<T>, Map<Integer, List<FlinkSourceSplit<T>>>> enumerator =
-      createEnumerator(enumContext);
+        createEnumerator(enumContext);
     checkpoint.forEach(
         (subtaskId, splitsForSubtask) -> enumerator.addSplitsBack(splitsForSubtask, subtaskId));
     return enumerator;
diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/io/source/LazyFlinkSourceSplitEnumerator.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/io/source/LazyFlinkSourceSplitEnumerator.java
index fdd14025a95a..4cb7e99c679d 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/io/source/LazyFlinkSourceSplitEnumerator.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/io/source/LazyFlinkSourceSplitEnumerator.java
@@ -19,18 +19,11 @@
 
 import java.io.IOException;
 import java.util.ArrayList;
-import java.util.Collections;
 import java.util.HashMap;
-import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
-import java.util.Optional;
-
 import javax.annotation.Nullable;
-
 import org.apache.beam.runners.flink.FlinkPipelineOptions;
-import org.apache.beam.runners.flink.translation.wrappers.streaming.io.source.FlinkSourceSplit;
-import org.apache.beam.runners.flink.translation.wrappers.streaming.io.source.FlinkSourceSplitEnumerator;
 import org.apache.beam.runners.flink.translation.wrappers.streaming.io.source.compat.SplitEnumeratorCompat;
 import org.apache.beam.sdk.io.BoundedSource;
 import org.apache.beam.sdk.io.FileBasedSource;
@@ -38,7 +31,6 @@
 import org.apache.beam.sdk.io.UnboundedSource;
 import org.apache.beam.sdk.options.PipelineOptions;
 import org.apache.flink.api.connector.source.SplitEnumeratorContext;
-import org.apache.flink.api.connector.source.SplitsAssignment;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -92,23 +84,23 @@ public void start() {
   @Override
   public void handleSplitRequest(int subtask, @Nullable String hostname) {
     if (!context.registeredReaders().containsKey(subtask)) {
-        // reader failed between sending the request and now. skip this request.
-        return;
+      // reader failed between sending the request and now. skip this request.
+      return;
     }
 
     if (LOG.isInfoEnabled()) {
-        final String hostInfo =
-                hostname == null ? "(no host locality info)" : "(on host '" + hostname + "')";
-        LOG.info("Subtask {} {} is requesting a file source split", subtask, hostInfo);
+      final String hostInfo =
+          hostname == null ? "(no host locality info)" : "(on host '" + hostname + "')";
+      LOG.info("Subtask {} {} is requesting a file source split", subtask, hostInfo);
     }
 
     if (!pendingSplits.isEmpty()) {
-        final FlinkSourceSplit<T> split = pendingSplits.remove(pendingSplits.size() - 1);
-        context.assignSplit(split, subtask);
-        LOG.info("Assigned split to subtask {} : {}", subtask, split);
+      final FlinkSourceSplit<T> split = pendingSplits.remove(pendingSplits.size() - 1);
+      context.assignSplit(split, subtask);
+      LOG.info("Assigned split to subtask {} : {}", subtask, split);
     } else {
-        context.signalNoMoreSplits(subtask);
-        LOG.info("No more splits available for subtask {}", subtask);
+      context.signalNoMoreSplits(subtask);
+      LOG.info("No more splits available for subtask {}", subtask);
     }
   }
 
diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/io/source/bounded/FlinkBoundedSourceReader.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/io/source/bounded/FlinkBoundedSourceReader.java
index d87d84d93dc2..6b23dd13c9b8 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/io/source/bounded/FlinkBoundedSourceReader.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/io/source/bounded/FlinkBoundedSourceReader.java
@@ -101,7 +101,7 @@ protected FlinkBoundedSourceReader(
   public InputStatus pollNext(ReaderOutput<WindowedValue<T>> output) throws Exception {
     checkExceptionAndMaybeThrow();
 
-    if(currentReader == null && currentSplitId == -1) {
+    if (currentReader == null && currentSplitId == -1) {
       context.sendSplitRequest();
     }
 
diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/state/FlinkStateInternals.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/state/FlinkStateInternals.java
index 388271cdd68a..2856813ce6ad 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/state/FlinkStateInternals.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/state/FlinkStateInternals.java
@@ -29,8 +29,6 @@
 import java.util.function.Function;
 import java.util.stream.Stream;
 import javax.annotation.Nonnull;
-
-import com.esotericsoftware.kryo.serializers.DefaultSerializers;
 import org.apache.beam.runners.core.StateInternals;
 import org.apache.beam.runners.core.StateNamespace;
 import org.apache.beam.runners.core.StateNamespaces;
@@ -254,17 +252,18 @@ private FlinkStateBinder(StateNamespace namespace, StateContext<?> stateContext)
     public <T2> ValueState<T2> bindValue(
         String id, StateSpec<ValueState<T2>> spec, Coder<T2> coder) {
       FlinkValueState<T2> valueState =
-          new FlinkValueState<>(flinkStateBackend, id, namespace, coder, namespaceKeySerializer, fasterCopy);
+          new FlinkValueState<>(
+              flinkStateBackend, id, namespace, coder, namespaceKeySerializer, fasterCopy);
       collectGlobalWindowStateDescriptor(
-          valueState.flinkStateDescriptor,
-          valueState.namespace, namespaceKeySerializer);
+          valueState.flinkStateDescriptor, valueState.namespace, namespaceKeySerializer);
       return valueState;
     }
 
     @Override
     public <T2> BagState<T2> bindBag(String id, StateSpec<BagState<T2>> spec, Coder<T2> elemCoder) {
       FlinkBagState<T2> bagState =
-          new FlinkBagState<>(flinkStateBackend, id, namespace, elemCoder, namespaceKeySerializer, fasterCopy);
+          new FlinkBagState<>(
+              flinkStateBackend, id, namespace, elemCoder, namespaceKeySerializer, fasterCopy);
       collectGlobalWindowStateDescriptor(
           bagState.flinkStateDescriptor, bagState.namespace, namespaceKeySerializer);
       return bagState;
@@ -273,7 +272,8 @@ public <T2> BagState<T2> bindBag(String id, StateSpec<BagState<T2>> spec, Coder<
     @Override
     public <T2> SetState<T2> bindSet(String id, StateSpec<SetState<T2>> spec, Coder<T2> elemCoder) {
       FlinkSetState<T2> setState =
-          new FlinkSetState<>(flinkStateBackend, id, namespace, elemCoder, namespaceKeySerializer, fasterCopy);
+          new FlinkSetState<>(
+              flinkStateBackend, id, namespace, elemCoder, namespaceKeySerializer, fasterCopy);
       collectGlobalWindowStateDescriptor(
           setState.flinkStateDescriptor, setState.namespace, namespaceKeySerializer);
       return setState;
@@ -287,7 +287,13 @@ public <KeyT, ValueT> MapState<KeyT, ValueT> bindMap(
         Coder<ValueT> mapValueCoder) {
       FlinkMapState<KeyT, ValueT> mapState =
           new FlinkMapState<>(
-              flinkStateBackend, id, namespace, mapKeyCoder, mapValueCoder, namespaceKeySerializer, fasterCopy);
+              flinkStateBackend,
+              id,
+              namespace,
+              mapKeyCoder,
+              mapValueCoder,
+              namespaceKeySerializer,
+              fasterCopy);
       collectGlobalWindowStateDescriptor(
           mapState.flinkStateDescriptor, mapState.namespace, namespaceKeySerializer);
       return mapState;
@@ -297,11 +303,12 @@ public <KeyT, ValueT> MapState<KeyT, ValueT> bindMap(
     public <T> OrderedListState<T> bindOrderedList(
         String id, StateSpec<OrderedListState<T>> spec, Coder<T> elemCoder) {
       FlinkOrderedListState<T> flinkOrderedListState =
-          new FlinkOrderedListState<>(flinkStateBackend, id, namespace, elemCoder, namespaceKeySerializer, fasterCopy);
+          new FlinkOrderedListState<>(
+              flinkStateBackend, id, namespace, elemCoder, namespaceKeySerializer, fasterCopy);
       collectGlobalWindowStateDescriptor(
           flinkOrderedListState.flinkStateDescriptor,
           flinkOrderedListState.namespace,
-              namespaceKeySerializer);
+          namespaceKeySerializer);
       return flinkOrderedListState;
     }
 
@@ -323,11 +330,15 @@ public <InputT, AccumT, OutputT> CombiningState<InputT, AccumT, OutputT> bindCom
         Combine.CombineFn<InputT, AccumT, OutputT> combineFn) {
       FlinkCombiningState<Object, InputT, AccumT, OutputT> combiningState =
           new FlinkCombiningState<>(
-              flinkStateBackend, id, combineFn, namespace, accumCoder, namespaceKeySerializer, fasterCopy);
+              flinkStateBackend,
+              id,
+              combineFn,
+              namespace,
+              accumCoder,
+              namespaceKeySerializer,
+              fasterCopy);
       collectGlobalWindowStateDescriptor(
-          combiningState.flinkStateDescriptor,
-          combiningState.namespace,
-              namespaceKeySerializer);
+          combiningState.flinkStateDescriptor, combiningState.namespace, namespaceKeySerializer);
       return combiningState;
     }
 
@@ -351,7 +362,7 @@ CombiningState<InputT, AccumT, OutputT> bindCombiningWithContext(
       collectGlobalWindowStateDescriptor(
           combiningStateWithContext.flinkStateDescriptor,
           combiningStateWithContext.namespace,
-              namespaceKeySerializer);
+          namespaceKeySerializer);
       return combiningStateWithContext;
     }
 
@@ -392,7 +403,7 @@ public Coder<? extends BoundedWindow> getCoder() {
     public FlinkStateNamespaceKeySerializer(Coder<? extends BoundedWindow> coder) {
       this.coder = coder;
     }
-    
+
     @Override
     public boolean isImmutableType() {
       return false;
@@ -434,7 +445,8 @@ public StateNamespace deserialize(DataInputView source) throws IOException {
     }
 
     @Override
-    public StateNamespace deserialize(StateNamespace reuse, DataInputView source) throws IOException {
+    public StateNamespace deserialize(StateNamespace reuse, DataInputView source)
+        throws IOException {
       return deserialize(source);
     }
 
@@ -460,14 +472,12 @@ public TypeSerializerSnapshot<StateNamespace> snapshotConfiguration() {
 
     /** Serializer configuration snapshot for compatibility and format evolution. */
     @SuppressWarnings("WeakerAccess")
-    public final static class FlinkStateNameSpaceSerializerSnapshot implements TypeSerializerSnapshot<StateNamespace> {
-
-      @Nullable
-      private Coder<? extends BoundedWindow> windowCoder;
+    public static final class FlinkStateNameSpaceSerializerSnapshot
+        implements TypeSerializerSnapshot<StateNamespace> {
 
-      public FlinkStateNameSpaceSerializerSnapshot(){
+      @Nullable private Coder<? extends BoundedWindow> windowCoder;
 
-      }
+      public FlinkStateNameSpaceSerializerSnapshot() {}
 
       FlinkStateNameSpaceSerializerSnapshot(FlinkStateNamespaceKeySerializer ser) {
         this.windowCoder = ser.getCoder();
@@ -484,7 +494,8 @@ public void writeSnapshot(DataOutputView out) throws IOException {
       }
 
       @Override
-      public void readSnapshot(int readVersion, DataInputView in, ClassLoader userCodeClassLoader) throws IOException {
+      public void readSnapshot(int readVersion, DataInputView in, ClassLoader userCodeClassLoader)
+          throws IOException {
         this.windowCoder = new JavaSerializer<Coder<? extends BoundedWindow>>().deserialize(in);
       }
 
@@ -494,7 +505,8 @@ public TypeSerializer<StateNamespace> restoreSerializer() {
       }
 
       @Override
-      public TypeSerializerSchemaCompatibility<StateNamespace> resolveSchemaCompatibility(TypeSerializer<StateNamespace> newSerializer) {
+      public TypeSerializerSchemaCompatibility<StateNamespace> resolveSchemaCompatibility(
+          TypeSerializer<StateNamespace> newSerializer) {
         return TypeSerializerSchemaCompatibility.compatibleAsIs();
       }
     }
@@ -521,7 +533,6 @@ private static class FlinkValueState<T> implements ValueState<T> {
       this.flinkStateBackend = flinkStateBackend;
       this.namespaceSerializer = namespaceSerializer;
 
-
       flinkStateDescriptor =
           new ValueStateDescriptor<>(stateId, new CoderTypeSerializer<>(coder, fasterCopy));
     }
@@ -530,8 +541,7 @@ private static class FlinkValueState<T> implements ValueState<T> {
     public void write(T input) {
       try {
         flinkStateBackend
-            .getPartitionedState(
-                namespace, namespaceSerializer, flinkStateDescriptor)
+            .getPartitionedState(namespace, namespaceSerializer, flinkStateDescriptor)
             .update(input);
       } catch (Exception e) {
         throw new RuntimeException("Error updating state.", e);
@@ -547,8 +557,7 @@ public ValueState<T> readLater() {
     public T read() {
       try {
         return flinkStateBackend
-            .getPartitionedState(
-                namespace, namespaceSerializer, flinkStateDescriptor)
+            .getPartitionedState(namespace, namespaceSerializer, flinkStateDescriptor)
             .value();
       } catch (Exception e) {
         throw new RuntimeException("Error reading state.", e);
@@ -621,7 +630,7 @@ public void clearRange(Instant minTimestamp, Instant limitTimestamp) {
       try {
         ListState<TimestampedValue<T>> partitionedState =
             flinkStateBackend.getPartitionedState(
-                    namespace, namespaceSerializer, flinkStateDescriptor);
+                namespace, namespaceSerializer, flinkStateDescriptor);
         partitionedState.update(Lists.newArrayList(sortedMap.values()));
       } catch (Exception e) {
         throw new RuntimeException("Error adding to bag state.", e);
@@ -638,7 +647,7 @@ public void add(TimestampedValue<T> value) {
       try {
         ListState<TimestampedValue<T>> partitionedState =
             flinkStateBackend.getPartitionedState(
-                    namespace, namespaceSerializer, flinkStateDescriptor);
+                namespace, namespaceSerializer, flinkStateDescriptor);
         partitionedState.add(value);
       } catch (Exception e) {
         throw new RuntimeException("Error adding to bag state.", e);
@@ -653,8 +662,7 @@ public Boolean read() {
           try {
             Iterable<TimestampedValue<T>> result =
                 flinkStateBackend
-                    .getPartitionedState(
-                            namespace, namespaceSerializer, flinkStateDescriptor)
+                    .getPartitionedState(namespace, namespaceSerializer, flinkStateDescriptor)
                     .get();
             return result == null;
           } catch (Exception e) {
@@ -680,7 +688,7 @@ private SortedMap<Instant, TimestampedValue<T>> readAsMap() {
       try {
         ListState<TimestampedValue<T>> partitionedState =
             flinkStateBackend.getPartitionedState(
-                    namespace, namespaceSerializer, flinkStateDescriptor);
+                namespace, namespaceSerializer, flinkStateDescriptor);
         listValues = MoreObjects.firstNonNull(partitionedState.get(), Collections.emptyList());
       } catch (Exception e) {
         throw new RuntimeException("Error reading state.", e);
@@ -702,8 +710,7 @@ public GroupingState<TimestampedValue<T>, Iterable<TimestampedValue<T>>> readLat
     public void clear() {
       try {
         flinkStateBackend
-            .getPartitionedState(
-                    namespace, namespaceSerializer, flinkStateDescriptor)
+            .getPartitionedState(namespace, namespaceSerializer, flinkStateDescriptor)
             .clear();
       } catch (Exception e) {
         throw new RuntimeException("Error clearing state.", e);
@@ -742,7 +749,7 @@ public void add(T input) {
       try {
         ListState<T> partitionedState =
             flinkStateBackend.getPartitionedState(
-                    namespace, namespaceSerializer, flinkStateDescriptor);
+                namespace, namespaceSerializer, flinkStateDescriptor);
         if (storesVoidValues) {
           Preconditions.checkState(input == null, "Expected to a null value but was: %s", input);
           // Flink does not allow storing null values
@@ -802,8 +809,7 @@ public Boolean read() {
           try {
             Iterable<T> result =
                 flinkStateBackend
-                    .getPartitionedState(
-                        namespace, namespaceSerializer, flinkStateDescriptor)
+                    .getPartitionedState(namespace, namespaceSerializer, flinkStateDescriptor)
                     .get();
             return result == null;
           } catch (Exception e) {
@@ -822,8 +828,7 @@ public ReadableState<Boolean> readLater() {
     public void clear() {
       try {
         flinkStateBackend
-            .getPartitionedState(
-                namespace, namespaceSerializer, flinkStateDescriptor)
+            .getPartitionedState(namespace, namespaceSerializer, flinkStateDescriptor)
             .clear();
       } catch (Exception e) {
         throw new RuntimeException("Error clearing state.", e);
@@ -928,8 +933,7 @@ public AccumT getAccum() {
       try {
         AccumT accum =
             flinkStateBackend
-                .getPartitionedState(
-                    namespace, namespaceSerializer, flinkStateDescriptor)
+                .getPartitionedState(namespace, namespaceSerializer, flinkStateDescriptor)
                 .value();
         return accum != null ? accum : combineFn.createAccumulator();
       } catch (Exception e) {
@@ -967,8 +971,7 @@ public ReadableState<Boolean> isEmpty() {
         public Boolean read() {
           try {
             return flinkStateBackend
-                    .getPartitionedState(
-                        namespace, namespaceSerializer, flinkStateDescriptor)
+                    .getPartitionedState(namespace, namespaceSerializer, flinkStateDescriptor)
                     .value()
                 == null;
           } catch (Exception e) {
@@ -987,8 +990,7 @@ public ReadableState<Boolean> readLater() {
     public void clear() {
       try {
         flinkStateBackend
-            .getPartitionedState(
-                namespace, namespaceSerializer, flinkStateDescriptor)
+            .getPartitionedState(namespace, namespaceSerializer, flinkStateDescriptor)
             .clear();
       } catch (Exception e) {
         throw new RuntimeException("Error clearing state.", e);
@@ -1096,8 +1098,7 @@ public AccumT getAccum() {
       try {
         AccumT accum =
             flinkStateBackend
-                .getPartitionedState(
-                    namespace, namespaceSerializer, flinkStateDescriptor)
+                .getPartitionedState(namespace, namespaceSerializer, flinkStateDescriptor)
                 .value();
         return accum != null ? accum : combineFn.createAccumulator(context);
       } catch (Exception e) {
@@ -1135,8 +1136,7 @@ public ReadableState<Boolean> isEmpty() {
         public Boolean read() {
           try {
             return flinkStateBackend
-                    .getPartitionedState(
-                        namespace, namespaceSerializer, flinkStateDescriptor)
+                    .getPartitionedState(namespace, namespaceSerializer, flinkStateDescriptor)
                     .value()
                 == null;
           } catch (Exception e) {
@@ -1155,8 +1155,7 @@ public ReadableState<Boolean> readLater() {
     public void clear() {
       try {
         flinkStateBackend
-            .getPartitionedState(
-                namespace, namespaceSerializer, flinkStateDescriptor)
+            .getPartitionedState(namespace, namespaceSerializer, flinkStateDescriptor)
             .clear();
       } catch (Exception e) {
         throw new RuntimeException("Error clearing state.", e);
@@ -1351,8 +1350,7 @@ public ReadableState<ValueT> get(final KeyT input) {
           try {
             ValueT value =
                 flinkStateBackend
-                    .getPartitionedState(
-                        namespace, namespaceSerializer, flinkStateDescriptor)
+                    .getPartitionedState(namespace, namespaceSerializer, flinkStateDescriptor)
                     .get(key);
             return (value != null) ? value : defaultValue;
           } catch (Exception e) {
@@ -1371,8 +1369,7 @@ public ReadableState<ValueT> get(final KeyT input) {
     public void put(KeyT key, ValueT value) {
       try {
         flinkStateBackend
-            .getPartitionedState(
-                namespace, namespaceSerializer, flinkStateDescriptor)
+            .getPartitionedState(namespace, namespaceSerializer, flinkStateDescriptor)
             .put(key, value);
       } catch (Exception e) {
         throw new RuntimeException("Error put kv to state.", e);
@@ -1385,14 +1382,12 @@ public ReadableState<ValueT> computeIfAbsent(
       try {
         ValueT current =
             flinkStateBackend
-                .getPartitionedState(
-                    namespace, namespaceSerializer, flinkStateDescriptor)
+                .getPartitionedState(namespace, namespaceSerializer, flinkStateDescriptor)
                 .get(key);
 
         if (current == null) {
           flinkStateBackend
-              .getPartitionedState(
-                  namespace, namespaceSerializer, flinkStateDescriptor)
+              .getPartitionedState(namespace, namespaceSerializer, flinkStateDescriptor)
               .put(key, mappingFunction.apply(key));
         }
         return ReadableStates.immediate(current);
@@ -1405,8 +1400,7 @@ public ReadableState<ValueT> computeIfAbsent(
     public void remove(KeyT key) {
       try {
         flinkStateBackend
-            .getPartitionedState(
-                namespace, namespaceSerializer, flinkStateDescriptor)
+            .getPartitionedState(namespace, namespaceSerializer, flinkStateDescriptor)
             .remove(key);
       } catch (Exception e) {
         throw new RuntimeException("Error remove map state key.", e);
@@ -1421,8 +1415,7 @@ public Iterable<KeyT> read() {
           try {
             Iterable<KeyT> result =
                 flinkStateBackend
-                    .getPartitionedState(
-                        namespace, namespaceSerializer, flinkStateDescriptor)
+                    .getPartitionedState(namespace, namespaceSerializer, flinkStateDescriptor)
                     .keys();
             return result != null ? ImmutableList.copyOf(result) : Collections.emptyList();
           } catch (Exception e) {
@@ -1445,8 +1438,7 @@ public Iterable<ValueT> read() {
           try {
             Iterable<ValueT> result =
                 flinkStateBackend
-                    .getPartitionedState(
-                        namespace, namespaceSerializer, flinkStateDescriptor)
+                    .getPartitionedState(namespace, namespaceSerializer, flinkStateDescriptor)
                     .values();
             return result != null ? ImmutableList.copyOf(result) : Collections.emptyList();
           } catch (Exception e) {
@@ -1469,8 +1461,7 @@ public Iterable<Map.Entry<KeyT, ValueT>> read() {
           try {
             Iterable<Map.Entry<KeyT, ValueT>> result =
                 flinkStateBackend
-                    .getPartitionedState(
-                        namespace, namespaceSerializer, flinkStateDescriptor)
+                    .getPartitionedState(namespace, namespaceSerializer, flinkStateDescriptor)
                     .entries();
             return result != null ? ImmutableList.copyOf(result) : Collections.emptyList();
           } catch (Exception e) {
@@ -1508,8 +1499,7 @@ public ReadableState<Iterable<Map.Entry<KeyT, ValueT>>> readLater() {
     public void clear() {
       try {
         flinkStateBackend
-            .getPartitionedState(
-                namespace, namespaceSerializer, flinkStateDescriptor)
+            .getPartitionedState(namespace, namespaceSerializer, flinkStateDescriptor)
             .clear();
       } catch (Exception e) {
         throw new RuntimeException("Error clearing state.", e);
@@ -1559,6 +1549,7 @@ private static class FlinkSetState<T> implements SetState<T> {
       this.flinkStateDescriptor =
           new MapStateDescriptor<>(
               stateId, new CoderTypeSerializer<>(coder, fasterCopy), BooleanSerializer.INSTANCE);
+      this.namespaceSerializer = namespaceSerializer;
     }
 
     @Override
@@ -1566,8 +1557,7 @@ public ReadableState<Boolean> contains(final T t) {
       try {
         Boolean result =
             flinkStateBackend
-                .getPartitionedState(
-                    namespace, namespaceSerializer, flinkStateDescriptor)
+                .getPartitionedState(namespace, namespaceSerializer, flinkStateDescriptor)
                 .get(t);
         return ReadableStates.immediate(result != null && result);
       } catch (Exception e) {
@@ -1595,8 +1585,7 @@ public ReadableState<Boolean> addIfAbsent(final T t) {
     public void remove(T t) {
       try {
         flinkStateBackend
-            .getPartitionedState(
-                namespace, namespaceSerializer, flinkStateDescriptor)
+            .getPartitionedState(namespace, namespaceSerializer, flinkStateDescriptor)
             .remove(t);
       } catch (Exception e) {
         throw new RuntimeException("Error remove value to state.", e);
@@ -1612,8 +1601,7 @@ public SetState<T> readLater() {
     public void add(T value) {
       try {
         flinkStateBackend
-            .getPartitionedState(
-                namespace, namespaceSerializer, flinkStateDescriptor)
+            .getPartitionedState(namespace, namespaceSerializer, flinkStateDescriptor)
             .put(value, true);
       } catch (Exception e) {
         throw new RuntimeException("Error add value to state.", e);
@@ -1628,8 +1616,7 @@ public Boolean read() {
           try {
             Iterable<T> result =
                 flinkStateBackend
-                    .getPartitionedState(
-                        namespace, namespaceSerializer, flinkStateDescriptor)
+                    .getPartitionedState(namespace, namespaceSerializer, flinkStateDescriptor)
                     .keys();
             return result == null || Iterables.isEmpty(result);
           } catch (Exception e) {
@@ -1649,8 +1636,7 @@ public Iterable<T> read() {
       try {
         Iterable<T> result =
             flinkStateBackend
-                .getPartitionedState(
-                    namespace, namespaceSerializer, flinkStateDescriptor)
+                .getPartitionedState(namespace, namespaceSerializer, flinkStateDescriptor)
                 .keys();
         return result != null ? ImmutableList.copyOf(result) : Collections.emptyList();
       } catch (Exception e) {
@@ -1662,8 +1648,7 @@ public Iterable<T> read() {
     public void clear() {
       try {
         flinkStateBackend
-            .getPartitionedState(
-                namespace, namespaceSerializer, flinkStateDescriptor)
+            .getPartitionedState(namespace, namespaceSerializer, flinkStateDescriptor)
             .clear();
       } catch (Exception e) {
         throw new RuntimeException("Error clearing state.", e);
@@ -1723,7 +1708,9 @@ public static class EarlyBinder implements StateBinder {
     private final FlinkStateNamespaceKeySerializer namespaceSerializer;
 
     public EarlyBinder(
-        KeyedStateBackend keyedStateBackend, SerializablePipelineOptions pipelineOptions, Coder<? extends BoundedWindow> windowCoder) {
+        KeyedStateBackend keyedStateBackend,
+        SerializablePipelineOptions pipelineOptions,
+        Coder<? extends BoundedWindow> windowCoder) {
       this.keyedStateBackend = keyedStateBackend;
       this.fasterCopy = pipelineOptions.get().as(FlinkPipelineOptions.class).getFasterCopy();
       this.namespaceSerializer = new FlinkStateNamespaceKeySerializer(windowCoder);
diff --git a/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/DoFnOperatorTest.java b/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/DoFnOperatorTest.java
index 4a25e06c6701..2cc0c8c7c13a 100644
--- a/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/DoFnOperatorTest.java
+++ b/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/DoFnOperatorTest.java
@@ -800,10 +800,10 @@ public void testGCForGlobalWindow() throws Exception {
     assertThat(testHarness.numKeyedStateEntries(), is(2));
 
     // Cleanup due to end of global window
-//    testHarness.processWatermark(
-//        GlobalWindow.INSTANCE.maxTimestamp().plus(Duration.millis(2)).getMillis());
-//    assertThat(testHarness.numEventTimeTimers(), is(0));
-//    assertThat(testHarness.numKeyedStateEntries(), is(0));
+    //    testHarness.processWatermark(
+    //        GlobalWindow.INSTANCE.maxTimestamp().plus(Duration.millis(2)).getMillis());
+    //    assertThat(testHarness.numEventTimeTimers(), is(0));
+    //    assertThat(testHarness.numKeyedStateEntries(), is(0));
 
     // Any new state will also be cleaned up on close
     testHarness.processElement(
diff --git a/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/WindowDoFnOperatorTest.java b/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/WindowDoFnOperatorTest.java
index 22713f6b33c6..a5dc643c5ca0 100644
--- a/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/WindowDoFnOperatorTest.java
+++ b/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/WindowDoFnOperatorTest.java
@@ -16,301 +16,293 @@
  * limitations under the License.
  */
 package org.apache.beam.runners.flink.translation.wrappers.streaming;
-//
-// import static java.util.Collections.emptyList;
-// import static java.util.Collections.emptyMap;
-// import static
-// org.apache.beam.runners.flink.translation.wrappers.streaming.StreamRecordStripper.stripStreamRecordFromWindowedValue;
-// import static org.apache.beam.sdk.transforms.windowing.PaneInfo.NO_FIRING;
-// import static org.apache.beam.sdk.transforms.windowing.PaneInfo.Timing.ON_TIME;
-// import static org.hamcrest.MatcherAssert.assertThat;
-// import static org.hamcrest.Matchers.containsInAnyOrder;
-// import static org.hamcrest.core.Is.is;
-// import static org.joda.time.Duration.standardMinutes;
-// import static org.junit.Assert.assertEquals;
-//
-// import java.io.ByteArrayOutputStream;
-// import java.nio.ByteBuffer;
-// import org.apache.beam.runners.core.KeyedWorkItem;
-// import org.apache.beam.runners.core.SystemReduceFn;
-// import org.apache.beam.runners.core.construction.SerializablePipelineOptions;
-// import org.apache.beam.runners.flink.FlinkPipelineOptions;
-// import
-// org.apache.beam.runners.flink.translation.wrappers.streaming.DoFnOperator.MultiOutputOutputManagerFactory;
-// import org.apache.beam.sdk.coders.Coder;
-// import org.apache.beam.sdk.coders.CoderRegistry;
-// import org.apache.beam.sdk.coders.KvCoder;
-// import org.apache.beam.sdk.coders.VarLongCoder;
-// import org.apache.beam.sdk.transforms.Sum;
-// import org.apache.beam.sdk.transforms.windowing.BoundedWindow;
-// import org.apache.beam.sdk.transforms.windowing.FixedWindows;
-// import org.apache.beam.sdk.transforms.windowing.IntervalWindow;
-// import org.apache.beam.sdk.transforms.windowing.PaneInfo;
-// import org.apache.beam.sdk.util.AppliedCombineFn;
-// import org.apache.beam.sdk.util.WindowedValue;
-// import org.apache.beam.sdk.util.WindowedValue.FullWindowedValueCoder;
-// import org.apache.beam.sdk.values.KV;
-// import org.apache.beam.sdk.values.TupleTag;
-// import org.apache.beam.sdk.values.WindowingStrategy;
-// import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.Iterables;
-// import org.apache.flink.api.java.functions.KeySelector;
-// import org.apache.flink.api.java.typeutils.GenericTypeInfo;
-// import org.apache.flink.runtime.checkpoint.OperatorSubtaskState;
-// import org.apache.flink.streaming.runtime.streamrecord.StreamRecord;
-// import org.apache.flink.streaming.util.KeyedOneInputStreamOperatorTestHarness;
-// import org.joda.time.Duration;
-// import org.joda.time.Instant;
-// import org.junit.Test;
-// import org.junit.runner.RunWith;
-// import org.junit.runners.JUnit4;
-//
-/// ** Tests for {@link WindowDoFnOperator}. */
-// @RunWith(JUnit4.class)
-// @SuppressWarnings({
-//  "rawtypes", // TODO(https://github.com/apache/beam/issues/20447)
-// })
-// public class WindowDoFnOperatorTest {
-//
-//  @Test
-//  public void testRestore() throws Exception {
-//    // test harness
-//    KeyedOneInputStreamOperatorTestHarness<
-//            ByteBuffer, WindowedValue<KeyedWorkItem<Long, Long>>, WindowedValue<KV<Long, Long>>>
-//        testHarness = createTestHarness(getWindowDoFnOperator());
-//    testHarness.open();
-//
-//    // process elements
-//    IntervalWindow window = new IntervalWindow(new Instant(0), Duration.millis(10_000));
-//    testHarness.processWatermark(0L);
-//    testHarness.processElement(
-//        Item.builder().key(1L).timestamp(1L).value(100L).window(window).build().toStreamRecord());
-//    testHarness.processElement(
-//        Item.builder().key(1L).timestamp(2L).value(20L).window(window).build().toStreamRecord());
-//    testHarness.processElement(
-//        Item.builder().key(2L).timestamp(3L).value(77L).window(window).build().toStreamRecord());
-//
-//    // create snapshot
-//    OperatorSubtaskState snapshot = testHarness.snapshot(0, 0);
-//    testHarness.close();
-//
-//    // restore from the snapshot
-//    testHarness = createTestHarness(getWindowDoFnOperator());
-//    testHarness.initializeState(snapshot);
-//    testHarness.open();
-//
-//    // close window
-//    testHarness.processWatermark(10_000L);
-//
-//    Iterable<WindowedValue<KV<Long, Long>>> output =
-//        stripStreamRecordFromWindowedValue(testHarness.getOutput());
-//
-//    assertEquals(2, Iterables.size(output));
-//    assertThat(
-//        output,
-//        containsInAnyOrder(
-//            WindowedValue.of(
-//                KV.of(1L, 120L),
-//                new Instant(9_999),
-//                window,
-//                PaneInfo.createPane(true, true, ON_TIME)),
-//            WindowedValue.of(
-//                KV.of(2L, 77L),
-//                new Instant(9_999),
-//                window,
-//                PaneInfo.createPane(true, true, ON_TIME))));
-//    // cleanup
-//    testHarness.close();
-//  }
-//
-//  @Test
-//  public void testTimerCleanupOfPendingTimerList() throws Exception {
-//    // test harness
-//    WindowDoFnOperator<Long, Long, Long> windowDoFnOperator = getWindowDoFnOperator();
-//    KeyedOneInputStreamOperatorTestHarness<
-//            ByteBuffer, WindowedValue<KeyedWorkItem<Long, Long>>, WindowedValue<KV<Long, Long>>>
-//        testHarness = createTestHarness(windowDoFnOperator);
-//    testHarness.open();
-//
-//    DoFnOperator<KV<Long, Long>, KeyedWorkItem<Long, Long>, KV<Long, Long>>.FlinkTimerInternals
-// timerInternals =
-//        windowDoFnOperator.timerInternals;
-//
-//    // process elements
-//    IntervalWindow window = new IntervalWindow(new Instant(0), Duration.millis(100));
-//    IntervalWindow window2 = new IntervalWindow(new Instant(100), Duration.millis(100));
-//    testHarness.processWatermark(0L);
-//
-//    // Use two different keys to check for correct watermark hold calculation
-//    testHarness.processElement(
-//        Item.builder().key(1L).timestamp(1L).value(100L).window(window).build().toStreamRecord());
-//    testHarness.processElement(
-//        Item.builder()
-//            .key(2L)
-//            .timestamp(150L)
-//            .value(150L)
-//            .window(window2)
-//            .build()
-//            .toStreamRecord());
-//
-//    testHarness.processWatermark(1);
-//
-//    // Note that the following is 1 because the state is key-partitioned
-//    assertThat(Iterables.size(timerInternals.pendingTimersById.keys()), is(1));
-//
-//    assertThat(testHarness.numKeyedStateEntries(), is(6));
-//    // close bundle
-//    testHarness.setProcessingTime(
-//        testHarness.getProcessingTime()
-//            + 2 * FlinkPipelineOptions.defaults().getMaxBundleTimeMills());
-//    assertThat(windowDoFnOperator.getCurrentOutputWatermark(), is(1L));
-//
-//    // close window
-//    testHarness.processWatermark(100L);
-//
-//    // Note that the following is zero because we only the first key is active
-//    assertThat(Iterables.size(timerInternals.pendingTimersById.keys()), is(0));
-//
-//    assertThat(testHarness.numKeyedStateEntries(), is(3));
-//
-//    // close bundle
-//    testHarness.setProcessingTime(
-//        testHarness.getProcessingTime()
-//            + 2 * FlinkPipelineOptions.defaults().getMaxBundleTimeMills());
-//    assertThat(windowDoFnOperator.getCurrentOutputWatermark(), is(100L));
-//
-//    testHarness.processWatermark(200L);
-//
-//    // All the state has been cleaned up
-//    assertThat(testHarness.numKeyedStateEntries(), is(0));
-//
-//    assertThat(
-//        stripStreamRecordFromWindowedValue(testHarness.getOutput()),
-//        containsInAnyOrder(
-//            WindowedValue.of(
-//                KV.of(1L, 100L), new Instant(99), window, PaneInfo.createPane(true, true,
-// ON_TIME)),
-//            WindowedValue.of(
-//                KV.of(2L, 150L),
-//                new Instant(199),
-//                window2,
-//                PaneInfo.createPane(true, true, ON_TIME))));
-//
-//    // cleanup
-//    testHarness.close();
-//  }
-//
-//  private WindowDoFnOperator<Long, Long, Long> getWindowDoFnOperator() {
-//    WindowingStrategy<Object, IntervalWindow> windowingStrategy =
-//        WindowingStrategy.of(FixedWindows.of(standardMinutes(1)));
-//
-//    TupleTag<KV<Long, Long>> outputTag = new TupleTag<>("main-output");
-//
-//    SystemReduceFn<Long, Long, long[], Long, BoundedWindow> reduceFn =
-//        SystemReduceFn.combining(
-//            VarLongCoder.of(),
-//            AppliedCombineFn.withInputCoder(
-//                Sum.ofLongs(),
-//                CoderRegistry.createDefault(),
-//                KvCoder.of(VarLongCoder.of(), VarLongCoder.of())));
-//
-//    Coder<IntervalWindow> windowCoder = windowingStrategy.getWindowFn().windowCoder();
-//    SingletonKeyedWorkItemCoder<Long, Long> workItemCoder =
-//        SingletonKeyedWorkItemCoder.of(VarLongCoder.of(), VarLongCoder.of(), windowCoder);
-//    FullWindowedValueCoder<KeyedWorkItem<Long, Long>> inputCoder =
-//        WindowedValue.getFullCoder(workItemCoder, windowCoder);
-//    FullWindowedValueCoder<KV<Long, Long>> outputCoder =
-//        WindowedValue.getFullCoder(KvCoder.of(VarLongCoder.of(), VarLongCoder.of()), windowCoder);
-//
-//    return new WindowDoFnOperator<Long, Long, Long>(
-//        reduceFn,
-//        "stepName",
-//        (Coder) inputCoder,
-//        outputTag,
-//        emptyList(),
-//        new MultiOutputOutputManagerFactory<>(
-//            outputTag,
-//            outputCoder,
-//            new SerializablePipelineOptions(FlinkPipelineOptions.defaults())),
-//        windowingStrategy,
-//        emptyMap(),
-//        emptyList(),
-//        FlinkPipelineOptions.defaults(),
-//        VarLongCoder.of(),
-//        new WorkItemKeySelector(
-//            VarLongCoder.of(), new SerializablePipelineOptions(FlinkPipelineOptions.defaults())));
-//  }
-//
-//  private KeyedOneInputStreamOperatorTestHarness<
-//          ByteBuffer, WindowedValue<KeyedWorkItem<Long, Long>>, WindowedValue<KV<Long, Long>>>
-//      createTestHarness(WindowDoFnOperator<Long, Long, Long> windowDoFnOperator) throws Exception
-// {
-//    return new KeyedOneInputStreamOperatorTestHarness<>(
-//        windowDoFnOperator,
-//        (KeySelector<WindowedValue<KeyedWorkItem<Long, Long>>, ByteBuffer>)
-//            o -> {
-//              try (ByteArrayOutputStream baos = new ByteArrayOutputStream()) {
-//                VarLongCoder.of().encode(o.getValue().key(), baos);
-//                return ByteBuffer.wrap(baos.toByteArray());
-//              }
-//            },
-//        new GenericTypeInfo<>(ByteBuffer.class));
-//  }
-//
-//  private static class Item {
-//
-//    static ItemBuilder builder() {
-//      return new ItemBuilder();
-//    }
-//
-//    private long key;
-//    private long value;
-//    private long timestamp;
-//    private IntervalWindow window;
-//
-//    StreamRecord<WindowedValue<KeyedWorkItem<Long, Long>>> toStreamRecord() {
-//      WindowedValue<Long> item = WindowedValue.of(value, new Instant(timestamp), window,
-// NO_FIRING);
-//      WindowedValue<KeyedWorkItem<Long, Long>> keyedItem =
-//          WindowedValue.of(
-//              new SingletonKeyedWorkItem<>(key, item), new Instant(timestamp), window, NO_FIRING);
-//      return new StreamRecord<>(keyedItem);
-//    }
-//
-//    private static final class ItemBuilder {
-//
-//      private long key;
-//      private long value;
-//      private long timestamp;
-//      private IntervalWindow window;
-//
-//      ItemBuilder key(long key) {
-//        this.key = key;
-//        return this;
-//      }
-//
-//      ItemBuilder value(long value) {
-//        this.value = value;
-//        return this;
-//      }
-//
-//      ItemBuilder timestamp(long timestamp) {
-//        this.timestamp = timestamp;
-//        return this;
-//      }
-//
-//      ItemBuilder window(IntervalWindow window) {
-//        this.window = window;
-//        return this;
-//      }
-//
-//      Item build() {
-//        Item item = new Item();
-//        item.key = this.key;
-//        item.value = this.value;
-//        item.window = this.window;
-//        item.timestamp = this.timestamp;
-//        return item;
-//      }
-//    }
-//  }
-// }
+
+import static java.util.Collections.emptyList;
+import static java.util.Collections.emptyMap;
+import static org.apache.beam.runners.flink.translation.wrappers.streaming.StreamRecordStripper.stripStreamRecordFromWindowedValue;
+import static org.apache.beam.sdk.transforms.windowing.PaneInfo.NO_FIRING;
+import static org.apache.beam.sdk.transforms.windowing.PaneInfo.Timing.ON_TIME;
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.containsInAnyOrder;
+import static org.hamcrest.core.Is.is;
+import static org.joda.time.Duration.standardMinutes;
+import static org.junit.Assert.assertEquals;
+
+import java.io.ByteArrayOutputStream;
+import java.nio.ByteBuffer;
+import org.apache.beam.runners.core.KeyedWorkItem;
+import org.apache.beam.runners.core.SystemReduceFn;
+import org.apache.beam.runners.core.construction.SerializablePipelineOptions;
+import org.apache.beam.runners.flink.FlinkPipelineOptions;
+import org.apache.beam.runners.flink.translation.wrappers.streaming.DoFnOperator.MultiOutputOutputManagerFactory;
+import org.apache.beam.sdk.coders.Coder;
+import org.apache.beam.sdk.coders.CoderRegistry;
+import org.apache.beam.sdk.coders.KvCoder;
+import org.apache.beam.sdk.coders.VarLongCoder;
+import org.apache.beam.sdk.transforms.Sum;
+import org.apache.beam.sdk.transforms.windowing.BoundedWindow;
+import org.apache.beam.sdk.transforms.windowing.FixedWindows;
+import org.apache.beam.sdk.transforms.windowing.IntervalWindow;
+import org.apache.beam.sdk.transforms.windowing.PaneInfo;
+import org.apache.beam.sdk.util.AppliedCombineFn;
+import org.apache.beam.sdk.util.WindowedValue;
+import org.apache.beam.sdk.util.WindowedValue.FullWindowedValueCoder;
+import org.apache.beam.sdk.values.KV;
+import org.apache.beam.sdk.values.TupleTag;
+import org.apache.beam.sdk.values.WindowingStrategy;
+import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.Iterables;
+import org.apache.flink.api.java.functions.KeySelector;
+import org.apache.flink.api.java.typeutils.GenericTypeInfo;
+import org.apache.flink.runtime.checkpoint.OperatorSubtaskState;
+import org.apache.flink.streaming.runtime.streamrecord.StreamRecord;
+import org.apache.flink.streaming.util.KeyedOneInputStreamOperatorTestHarness;
+import org.joda.time.Duration;
+import org.joda.time.Instant;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+/** Tests for {@link WindowDoFnOperator}. */
+@RunWith(JUnit4.class)
+@SuppressWarnings({
+  "rawtypes", // TODO(https://github.com/apache/beam/issues/20447)
+})
+public class WindowDoFnOperatorTest {
+
+  @Test
+  public void testRestore() throws Exception {
+    // test harness
+    KeyedOneInputStreamOperatorTestHarness<
+            ByteBuffer, WindowedValue<KV<Long, Long>>, WindowedValue<KV<Long, Long>>>
+        testHarness = createTestHarness(getWindowDoFnOperator());
+    testHarness.open();
+
+    // process elements
+    IntervalWindow window = new IntervalWindow(new Instant(0), Duration.millis(10_000));
+    testHarness.processWatermark(0L);
+    testHarness.processElement(
+        Item.builder().key(1L).timestamp(1L).value(100L).window(window).build().toStreamRecord());
+    testHarness.processElement(
+        Item.builder().key(1L).timestamp(2L).value(20L).window(window).build().toStreamRecord());
+    testHarness.processElement(
+        Item.builder().key(2L).timestamp(3L).value(77L).window(window).build().toStreamRecord());
+
+    // create snapshot
+    OperatorSubtaskState snapshot = testHarness.snapshot(0, 0);
+    testHarness.close();
+
+    // restore from the snapshot
+    testHarness = createTestHarness(getWindowDoFnOperator());
+    testHarness.initializeState(snapshot);
+    testHarness.open();
+
+    // close window
+    testHarness.processWatermark(10_000L);
+
+    Iterable<WindowedValue<KV<Long, Long>>> output =
+        stripStreamRecordFromWindowedValue(testHarness.getOutput());
+
+    assertEquals(2, Iterables.size(output));
+    assertThat(
+        output,
+        containsInAnyOrder(
+            WindowedValue.of(
+                KV.of(1L, 120L),
+                new Instant(9_999),
+                window,
+                PaneInfo.createPane(true, true, ON_TIME)),
+            WindowedValue.of(
+                KV.of(2L, 77L),
+                new Instant(9_999),
+                window,
+                PaneInfo.createPane(true, true, ON_TIME))));
+    // cleanup
+    testHarness.close();
+  }
+
+  @Test
+  public void testTimerCleanupOfPendingTimerList() throws Exception {
+    // test harness
+    WindowDoFnOperator<Long, Long, Long> windowDoFnOperator = getWindowDoFnOperator();
+    KeyedOneInputStreamOperatorTestHarness<
+            ByteBuffer, WindowedValue<KV<Long, Long>>, WindowedValue<KV<Long, Long>>>
+        testHarness = createTestHarness(windowDoFnOperator);
+    testHarness.open();
+
+    DoFnOperator<KV<Long, Long>, KeyedWorkItem<Long, Long>, KV<Long, Long>>.FlinkTimerInternals
+        timerInternals = windowDoFnOperator.timerInternals;
+
+    // process elements
+    IntervalWindow window = new IntervalWindow(new Instant(0), Duration.millis(100));
+    IntervalWindow window2 = new IntervalWindow(new Instant(100), Duration.millis(100));
+    testHarness.processWatermark(0L);
+
+    // Use two different keys to check for correct watermark hold calculation
+    testHarness.processElement(
+        Item.builder().key(1L).timestamp(1L).value(100L).window(window).build().toStreamRecord());
+    testHarness.processElement(
+        Item.builder()
+            .key(2L)
+            .timestamp(150L)
+            .value(150L)
+            .window(window2)
+            .build()
+            .toStreamRecord());
+
+    testHarness.processWatermark(1);
+
+    // Note that the following is 1 because the state is key-partitioned
+    assertThat(Iterables.size(timerInternals.pendingTimersById.keys()), is(1));
+
+    assertThat(testHarness.numKeyedStateEntries(), is(6));
+    // close bundle
+    testHarness.setProcessingTime(
+        testHarness.getProcessingTime()
+            + 2 * FlinkPipelineOptions.defaults().getMaxBundleTimeMills());
+    assertThat(windowDoFnOperator.getCurrentOutputWatermark(), is(1L));
+
+    // close window
+    testHarness.processWatermark(100L);
+
+    // Note that the following is zero because we only the first key is active
+    assertThat(Iterables.size(timerInternals.pendingTimersById.keys()), is(0));
+
+    assertThat(testHarness.numKeyedStateEntries(), is(3));
+
+    // close bundle
+    testHarness.setProcessingTime(
+        testHarness.getProcessingTime()
+            + 2 * FlinkPipelineOptions.defaults().getMaxBundleTimeMills());
+    assertThat(windowDoFnOperator.getCurrentOutputWatermark(), is(100L));
+
+    testHarness.processWatermark(200L);
+
+    // All the state has been cleaned up
+    assertThat(testHarness.numKeyedStateEntries(), is(0));
+
+    assertThat(
+        stripStreamRecordFromWindowedValue(testHarness.getOutput()),
+        containsInAnyOrder(
+            WindowedValue.of(
+                KV.of(1L, 100L), new Instant(99), window, PaneInfo.createPane(true, true, ON_TIME)),
+            WindowedValue.of(
+                KV.of(2L, 150L),
+                new Instant(199),
+                window2,
+                PaneInfo.createPane(true, true, ON_TIME))));
+
+    // cleanup
+    testHarness.close();
+  }
+
+  private WindowDoFnOperator<Long, Long, Long> getWindowDoFnOperator() {
+    WindowingStrategy<Object, IntervalWindow> windowingStrategy =
+        WindowingStrategy.of(FixedWindows.of(standardMinutes(1)));
+
+    TupleTag<KV<Long, Long>> outputTag = new TupleTag<>("main-output");
+
+    SystemReduceFn<Long, Long, long[], Long, BoundedWindow> reduceFn =
+        SystemReduceFn.combining(
+            VarLongCoder.of(),
+            AppliedCombineFn.withInputCoder(
+                Sum.ofLongs(),
+                CoderRegistry.createDefault(),
+                KvCoder.of(VarLongCoder.of(), VarLongCoder.of())));
+
+    Coder<IntervalWindow> windowCoder = windowingStrategy.getWindowFn().windowCoder();
+    SingletonKeyedWorkItemCoder<Long, Long> workItemCoder =
+        SingletonKeyedWorkItemCoder.of(VarLongCoder.of(), VarLongCoder.of(), windowCoder);
+    FullWindowedValueCoder<KeyedWorkItem<Long, Long>> inputCoder =
+        WindowedValue.getFullCoder(workItemCoder, windowCoder);
+    FullWindowedValueCoder<KV<Long, Long>> outputCoder =
+        WindowedValue.getFullCoder(KvCoder.of(VarLongCoder.of(), VarLongCoder.of()), windowCoder);
+
+    return new WindowDoFnOperator<Long, Long, Long>(
+        reduceFn,
+        "stepName",
+        (Coder) inputCoder,
+        outputTag,
+        emptyList(),
+        new MultiOutputOutputManagerFactory<>(
+            outputTag,
+            outputCoder,
+            new SerializablePipelineOptions(FlinkPipelineOptions.defaults())),
+        windowingStrategy,
+        emptyMap(),
+        emptyList(),
+        FlinkPipelineOptions.defaults(),
+        VarLongCoder.of(),
+        new WorkItemKeySelector(
+            VarLongCoder.of(), new SerializablePipelineOptions(FlinkPipelineOptions.defaults())));
+  }
+
+  private KeyedOneInputStreamOperatorTestHarness<
+          ByteBuffer, WindowedValue<KV<Long, Long>>, WindowedValue<KV<Long, Long>>>
+      createTestHarness(WindowDoFnOperator<Long, Long, Long> windowDoFnOperator) throws Exception {
+    return new KeyedOneInputStreamOperatorTestHarness<>(
+        windowDoFnOperator,
+        (KeySelector<WindowedValue<KV<Long, Long>>, ByteBuffer>)
+            o -> {
+              try (ByteArrayOutputStream baos = new ByteArrayOutputStream()) {
+                VarLongCoder.of().encode(o.getValue().getKey(), baos);
+                return ByteBuffer.wrap(baos.toByteArray());
+              }
+            },
+        new GenericTypeInfo<>(ByteBuffer.class));
+  }
+
+  private static class Item {
+
+    static ItemBuilder builder() {
+      return new ItemBuilder();
+    }
+
+    private long key;
+    private long value;
+    private long timestamp;
+    private IntervalWindow window;
+
+    StreamRecord<WindowedValue<KV<Long, Long>>> toStreamRecord() {
+      WindowedValue<KV<Long, Long>> keyedItem =
+          WindowedValue.of(KV.of(key, value), new Instant(timestamp), window, NO_FIRING);
+      return new StreamRecord<>(keyedItem);
+    }
+
+    private static final class ItemBuilder {
+
+      private long key;
+      private long value;
+      private long timestamp;
+      private IntervalWindow window;
+
+      ItemBuilder key(long key) {
+        this.key = key;
+        return this;
+      }
+
+      ItemBuilder value(long value) {
+        this.value = value;
+        return this;
+      }
+
+      ItemBuilder timestamp(long timestamp) {
+        this.timestamp = timestamp;
+        return this;
+      }
+
+      ItemBuilder window(IntervalWindow window) {
+        this.window = window;
+        return this;
+      }
+
+      Item build() {
+        Item item = new Item();
+        item.key = this.key;
+        item.value = this.value;
+        item.window = this.window;
+        item.timestamp = this.timestamp;
+        return item;
+      }
+    }
+  }
+}
diff --git a/website/www/site/layouts/shortcodes/flink_java_pipeline_options.html b/website/www/site/layouts/shortcodes/flink_java_pipeline_options.html
index 60f1fd39bd13..a3526d7d0d28 100644
--- a/website/www/site/layouts/shortcodes/flink_java_pipeline_options.html
+++ b/website/www/site/layouts/shortcodes/flink_java_pipeline_options.html
@@ -107,6 +107,11 @@
   <td>Address of the Flink Master where the Pipeline should be executed. Can either be of the form "host:port" or one of the special values [local], [collection] or [auto].</td>
   <td>Default: <code>[auto]</code></td>
 </tr>
+<tr>
+  <td><code>forceSlotSharingGroup</code></td>
+  <td>Set a slot sharing group for all bounded sources. This is required when using Datastream to have the same scheduling behaviour as the Dataset API.</td>
+  <td>Default: <code>true</code></td>
+</tr>
 <tr>
   <td><code>forceUnalignedCheckpointEnabled</code></td>
   <td>Forces unaligned checkpoints, particularly allowing them for iterative jobs.</td>
diff --git a/website/www/site/layouts/shortcodes/flink_python_pipeline_options.html b/website/www/site/layouts/shortcodes/flink_python_pipeline_options.html
index 4faad5a994ba..183dacfd5a09 100644
--- a/website/www/site/layouts/shortcodes/flink_python_pipeline_options.html
+++ b/website/www/site/layouts/shortcodes/flink_python_pipeline_options.html
@@ -107,6 +107,11 @@
   <td>Address of the Flink Master where the Pipeline should be executed. Can either be of the form "host:port" or one of the special values [local], [collection] or [auto].</td>
   <td>Default: <code>[auto]</code></td>
 </tr>
+<tr>
+  <td><code>force_slot_sharing_group</code></td>
+  <td>Set a slot sharing group for all bounded sources. This is required when using Datastream to have the same scheduling behaviour as the Dataset API.</td>
+  <td>Default: <code>true</code></td>
+</tr>
 <tr>
   <td><code>force_unaligned_checkpoint_enabled</code></td>
   <td>Forces unaligned checkpoints, particularly allowing them for iterative jobs.</td>

From ff9cb80368ffe5554c3f85daa8e8361cd89f17fb Mon Sep 17 00:00:00 2001
From: jto <boudhevil@gmail.com>
Date: Thu, 29 Aug 2024 14:50:58 +0200
Subject: [PATCH 17/26] [Flink] fix WindowDoFnOperatorTest

---
 .../streaming/WindowDoFnOperatorTest.java     | 20 +++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/WindowDoFnOperatorTest.java b/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/WindowDoFnOperatorTest.java
index a5dc643c5ca0..408e8d05a4a0 100644
--- a/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/WindowDoFnOperatorTest.java
+++ b/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/WindowDoFnOperatorTest.java
@@ -74,7 +74,7 @@ public void testRestore() throws Exception {
     // test harness
     KeyedOneInputStreamOperatorTestHarness<
             ByteBuffer, WindowedValue<KV<Long, Long>>, WindowedValue<KV<Long, Long>>>
-        testHarness = createTestHarness(getWindowDoFnOperator());
+        testHarness = createTestHarness(getWindowDoFnOperator(true));
     testHarness.open();
 
     // process elements
@@ -92,7 +92,7 @@ public void testRestore() throws Exception {
     testHarness.close();
 
     // restore from the snapshot
-    testHarness = createTestHarness(getWindowDoFnOperator());
+    testHarness = createTestHarness(getWindowDoFnOperator(true));
     testHarness.initializeState(snapshot);
     testHarness.open();
 
@@ -123,7 +123,7 @@ public void testRestore() throws Exception {
   @Test
   public void testTimerCleanupOfPendingTimerList() throws Exception {
     // test harness
-    WindowDoFnOperator<Long, Long, Long> windowDoFnOperator = getWindowDoFnOperator();
+    WindowDoFnOperator<Long, Long, Long> windowDoFnOperator = getWindowDoFnOperator(true);
     KeyedOneInputStreamOperatorTestHarness<
             ByteBuffer, WindowedValue<KV<Long, Long>>, WindowedValue<KV<Long, Long>>>
         testHarness = createTestHarness(windowDoFnOperator);
@@ -195,7 +195,7 @@ public void testTimerCleanupOfPendingTimerList() throws Exception {
     testHarness.close();
   }
 
-  private WindowDoFnOperator<Long, Long, Long> getWindowDoFnOperator() {
+  private WindowDoFnOperator<Long, Long, Long> getWindowDoFnOperator(boolean streaming) {
     WindowingStrategy<Object, IntervalWindow> windowingStrategy =
         WindowingStrategy.of(FixedWindows.of(standardMinutes(1)));
 
@@ -217,6 +217,9 @@ private WindowDoFnOperator<Long, Long, Long> getWindowDoFnOperator() {
     FullWindowedValueCoder<KV<Long, Long>> outputCoder =
         WindowedValue.getFullCoder(KvCoder.of(VarLongCoder.of(), VarLongCoder.of()), windowCoder);
 
+    FlinkPipelineOptions options = FlinkPipelineOptions.defaults();
+    options.setStreaming(streaming);
+
     return new WindowDoFnOperator<Long, Long, Long>(
         reduceFn,
         "stepName",
@@ -224,16 +227,13 @@ private WindowDoFnOperator<Long, Long, Long> getWindowDoFnOperator() {
         outputTag,
         emptyList(),
         new MultiOutputOutputManagerFactory<>(
-            outputTag,
-            outputCoder,
-            new SerializablePipelineOptions(FlinkPipelineOptions.defaults())),
+            outputTag, outputCoder, new SerializablePipelineOptions(options)),
         windowingStrategy,
         emptyMap(),
         emptyList(),
-        FlinkPipelineOptions.defaults(),
+        options,
         VarLongCoder.of(),
-        new WorkItemKeySelector(
-            VarLongCoder.of(), new SerializablePipelineOptions(FlinkPipelineOptions.defaults())));
+        new WorkItemKeySelector(VarLongCoder.of(), new SerializablePipelineOptions(options)));
   }
 
   private KeyedOneInputStreamOperatorTestHarness<

From 6fddd1b6114eb5fba3c5afd733afd7b96442d0e8 Mon Sep 17 00:00:00 2001
From: jto <boudhevil@gmail.com>
Date: Fri, 30 Aug 2024 11:54:46 +0200
Subject: [PATCH 18/26] [Flink] spotless

[Flink] spotless
---
 .../runners/core/GroupAlsoByWindowViaWindowSetNewDoFn.java | 3 ++-
 .../flink/translation/types/CoderTypeSerializer.java       | 7 ++++++-
 .../runners/flink/FlinkStreamingTransformTranslators.java  | 1 -
 .../flink/translation/wrappers/streaming/DoFnOperator.java | 3 ++-
 4 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/runners/core-java/src/main/java/org/apache/beam/runners/core/GroupAlsoByWindowViaWindowSetNewDoFn.java b/runners/core-java/src/main/java/org/apache/beam/runners/core/GroupAlsoByWindowViaWindowSetNewDoFn.java
index cc657413f6f1..3e42bb54494e 100644
--- a/runners/core-java/src/main/java/org/apache/beam/runners/core/GroupAlsoByWindowViaWindowSetNewDoFn.java
+++ b/runners/core-java/src/main/java/org/apache/beam/runners/core/GroupAlsoByWindowViaWindowSetNewDoFn.java
@@ -126,7 +126,8 @@ public void processElement(ProcessContext c) throws Exception {
         new ReduceFnRunner<>(
             key,
             windowingStrategy,
-            ExecutableTriggerStateMachine.create(TriggerStateMachines.stateMachineForTrigger(triggerProto)),
+            ExecutableTriggerStateMachine.create(
+                TriggerStateMachines.stateMachineForTrigger(triggerProto)),
             stateInternals,
             timerInternals,
             outputWindowedValue(),
diff --git a/runners/flink/1.15/src/main/java/org/apache/beam/runners/flink/translation/types/CoderTypeSerializer.java b/runners/flink/1.15/src/main/java/org/apache/beam/runners/flink/translation/types/CoderTypeSerializer.java
index 6c21ea8edc00..decee51128a4 100644
--- a/runners/flink/1.15/src/main/java/org/apache/beam/runners/flink/translation/types/CoderTypeSerializer.java
+++ b/runners/flink/1.15/src/main/java/org/apache/beam/runners/flink/translation/types/CoderTypeSerializer.java
@@ -53,7 +53,12 @@ public class CoderTypeSerializer<T> extends TypeSerializer<T> {
   private final boolean fasterCopy;
 
   public CoderTypeSerializer(Coder<T> coder, SerializablePipelineOptions pipelineOptions) {
-    this(coder, Preconditions.checkNotNull(pipelineOptions).get().as(FlinkPipelineOptions.class).getFasterCopy());
+    this(
+        coder,
+        Preconditions.checkNotNull(pipelineOptions)
+            .get()
+            .as(FlinkPipelineOptions.class)
+            .getFasterCopy());
   }
 
   public CoderTypeSerializer(Coder<T> coder, boolean fasterCopy) {
diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingTransformTranslators.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingTransformTranslators.java
index 77f6812c4143..f8401efb343a 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingTransformTranslators.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingTransformTranslators.java
@@ -38,7 +38,6 @@
 import org.apache.beam.runners.flink.translation.types.CoderTypeInformation;
 import org.apache.beam.runners.flink.translation.wrappers.streaming.DoFnOperator;
 import org.apache.beam.runners.flink.translation.wrappers.streaming.KvToByteBufferKeySelector;
-import org.apache.beam.runners.flink.translation.wrappers.streaming.ProcessingTimeCallbackCompat;
 import org.apache.beam.runners.flink.translation.wrappers.streaming.SingletonKeyedWorkItem;
 import org.apache.beam.runners.flink.translation.wrappers.streaming.SingletonKeyedWorkItemCoder;
 import org.apache.beam.runners.flink.translation.wrappers.streaming.SplittableDoFnOperator;
diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/DoFnOperator.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/DoFnOperator.java
index f1c30615defe..5c6471ee9c23 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/DoFnOperator.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/DoFnOperator.java
@@ -145,7 +145,8 @@
   "keyfor",
   "nullness"
 }) // TODO(https://github.com/apache/beam/issues/20497)
-public class DoFnOperator<PreInputT, InputT, OutputT> extends AbstractStreamOperator<WindowedValue<OutputT>>
+public class DoFnOperator<PreInputT, InputT, OutputT>
+    extends AbstractStreamOperator<WindowedValue<OutputT>>
     implements OneInputStreamOperator<WindowedValue<PreInputT>, WindowedValue<OutputT>>,
         TwoInputStreamOperator<WindowedValue<PreInputT>, RawUnionValue, WindowedValue<OutputT>>,
         Triggerable<ByteBuffer, TimerData> {

From 7d62bf58f4a5eaa01567c66705834c19c7438aa9 Mon Sep 17 00:00:00 2001
From: jto <boudhevil@gmail.com>
Date: Tue, 10 Sep 2024 11:02:03 +0200
Subject: [PATCH 19/26] [Flink] fix broken tests

---
 .../runners/flink/FlinkSubmissionTest.java     |  3 ++-
 .../wrappers/streaming/DoFnOperatorTest.java   | 18 ++++++++++--------
 2 files changed, 12 insertions(+), 9 deletions(-)

diff --git a/runners/flink/src/test/java/org/apache/beam/runners/flink/FlinkSubmissionTest.java b/runners/flink/src/test/java/org/apache/beam/runners/flink/FlinkSubmissionTest.java
index cf860717def3..508cb04f7b14 100644
--- a/runners/flink/src/test/java/org/apache/beam/runners/flink/FlinkSubmissionTest.java
+++ b/runners/flink/src/test/java/org/apache/beam/runners/flink/FlinkSubmissionTest.java
@@ -135,6 +135,7 @@ public void testDetachedSubmissionStreaming() throws Exception {
 
   private void runSubmission(boolean isDetached, boolean isStreaming) throws Exception {
     PipelineOptions options = PipelineOptionsFactory.create();
+    options.as(FlinkPipelineOptions.class).setStreaming(isStreaming);
     options.setTempLocation(TEMP_FOLDER.getRoot().getPath());
     String jarPath =
         Iterables.getFirst(
@@ -171,7 +172,7 @@ private void waitUntilJobIsCompleted() throws Exception {
               .allMatch(jobStatus -> jobStatus.getJobState().name().equals("FINISHED"))) {
         return;
       }
-      Thread.sleep(50);
+      Thread.sleep(100);
     }
   }
 
diff --git a/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/DoFnOperatorTest.java b/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/DoFnOperatorTest.java
index 2cc0c8c7c13a..67e21a17bc6b 100644
--- a/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/DoFnOperatorTest.java
+++ b/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/DoFnOperatorTest.java
@@ -800,10 +800,10 @@ public void testGCForGlobalWindow() throws Exception {
     assertThat(testHarness.numKeyedStateEntries(), is(2));
 
     // Cleanup due to end of global window
-    //    testHarness.processWatermark(
-    //        GlobalWindow.INSTANCE.maxTimestamp().plus(Duration.millis(2)).getMillis());
-    //    assertThat(testHarness.numEventTimeTimers(), is(0));
-    //    assertThat(testHarness.numKeyedStateEntries(), is(0));
+    testHarness.processWatermark(
+        GlobalWindow.INSTANCE.maxTimestamp().plus(Duration.millis(2)).getMillis());
+    assertThat(testHarness.numEventTimeTimers(), is(0));
+    assertThat(testHarness.numKeyedStateEntries(), is(0));
 
     // Any new state will also be cleaned up on close
     testHarness.processElement(
@@ -866,6 +866,9 @@ public void onTimer(OnTimerContext context, @StateId(stateId) ValueState<String>
     KeySelector<WindowedValue<KV<String, Integer>>, ByteBuffer> keySelector =
         e -> FlinkKeyUtils.encodeKey(e.getValue().getKey(), StringUtf8Coder.of());
 
+    FlinkPipelineOptions options = FlinkPipelineOptions.defaults();
+    options.setStreaming(true);
+
     DoFnOperator<KV<String, Integer>, KV<String, Integer>, KV<String, Integer>> doFnOperator =
         new DoFnOperator<>(
             fn,
@@ -875,11 +878,11 @@ public void onTimer(OnTimerContext context, @StateId(stateId) ValueState<String>
             outputTag,
             Collections.emptyList(),
             new DoFnOperator.MultiOutputOutputManagerFactory<>(
-                outputTag, coder, new SerializablePipelineOptions(FlinkPipelineOptions.defaults())),
+                outputTag, coder, new SerializablePipelineOptions(options)),
             windowingStrategy,
             new HashMap<>(), /* side-input mapping */
             Collections.emptyList(), /* side inputs */
-            FlinkPipelineOptions.defaults(),
+            options,
             StringUtf8Coder.of(), /* key coder */
             keySelector,
             DoFnSchemaInformation.create(),
@@ -888,8 +891,7 @@ outputTag, coder, new SerializablePipelineOptions(FlinkPipelineOptions.defaults(
     return new KeyedOneInputStreamOperatorTestHarness<>(
         doFnOperator,
         keySelector,
-        new CoderTypeInformation<>(
-            FlinkKeyUtils.ByteBufferCoder.of(), FlinkPipelineOptions.defaults()));
+        new CoderTypeInformation<>(FlinkKeyUtils.ByteBufferCoder.of(), options));
   }
 
   @Test

From 98a99f444a8fd93ee5b5d09ea7cea6eaeb8117a1 Mon Sep 17 00:00:00 2001
From: jto <boudhevil@gmail.com>
Date: Thu, 12 Sep 2024 12:12:57 +0200
Subject: [PATCH 20/26] [Flink] Remove 1.14 compat code

---
 .../streaming/io/source/LazyFlinkSourceSplitEnumerator.java  | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/io/source/LazyFlinkSourceSplitEnumerator.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/io/source/LazyFlinkSourceSplitEnumerator.java
index 4cb7e99c679d..5f394391c25d 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/io/source/LazyFlinkSourceSplitEnumerator.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/io/source/LazyFlinkSourceSplitEnumerator.java
@@ -24,12 +24,12 @@
 import java.util.Map;
 import javax.annotation.Nullable;
 import org.apache.beam.runners.flink.FlinkPipelineOptions;
-import org.apache.beam.runners.flink.translation.wrappers.streaming.io.source.compat.SplitEnumeratorCompat;
 import org.apache.beam.sdk.io.BoundedSource;
 import org.apache.beam.sdk.io.FileBasedSource;
 import org.apache.beam.sdk.io.Source;
 import org.apache.beam.sdk.io.UnboundedSource;
 import org.apache.beam.sdk.options.PipelineOptions;
+import org.apache.flink.api.connector.source.SplitEnumerator;
 import org.apache.flink.api.connector.source.SplitEnumeratorContext;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -46,7 +46,7 @@
  * @param <T> The output type of the encapsulated Beam {@link Source}.
  */
 public class LazyFlinkSourceSplitEnumerator<T>
-    implements SplitEnumeratorCompat<FlinkSourceSplit<T>, Map<Integer, List<FlinkSourceSplit<T>>>> {
+    implements SplitEnumerator<FlinkSourceSplit<T>, Map<Integer, List<FlinkSourceSplit<T>>>> {
   private static final Logger LOG = LoggerFactory.getLogger(LazyFlinkSourceSplitEnumerator.class);
   private final SplitEnumeratorContext<FlinkSourceSplit<T>> context;
   private final Source<T> beamSource;
@@ -121,7 +121,6 @@ public Map<Integer, List<FlinkSourceSplit<T>>> snapshotState(long checkpointId)
     return snapshotState();
   }
 
-  @Override
   public Map<Integer, List<FlinkSourceSplit<T>>> snapshotState() throws Exception {
     // For type compatibility reasons, we return a Map but we do not actually care about the key
     Map<Integer, List<FlinkSourceSplit<T>>> state = new HashMap<>(1);

From 21e83bd2182c6044cb2c2bb77c2f11d8795b65d6 Mon Sep 17 00:00:00 2001
From: jto <boudhevil@gmail.com>
Date: Thu, 12 Sep 2024 13:53:27 +0200
Subject: [PATCH 21/26] [Flink] Fix flaky test

---
 .../runners/flink/FlinkSubmissionTest.java    | 49 +++++++++++--------
 1 file changed, 29 insertions(+), 20 deletions(-)

diff --git a/runners/flink/src/test/java/org/apache/beam/runners/flink/FlinkSubmissionTest.java b/runners/flink/src/test/java/org/apache/beam/runners/flink/FlinkSubmissionTest.java
index 508cb04f7b14..8e4c3255fac5 100644
--- a/runners/flink/src/test/java/org/apache/beam/runners/flink/FlinkSubmissionTest.java
+++ b/runners/flink/src/test/java/org/apache/beam/runners/flink/FlinkSubmissionTest.java
@@ -26,6 +26,7 @@
 import java.util.Collection;
 import java.util.Map;
 import java.util.concurrent.TimeUnit;
+import java.util.stream.Collectors;
 import org.apache.beam.sdk.Pipeline;
 import org.apache.beam.sdk.io.GenerateSequence;
 import org.apache.beam.sdk.options.PipelineOptions;
@@ -49,6 +50,8 @@
 import org.junit.Test;
 import org.junit.rules.TemporaryFolder;
 import org.junit.rules.Timeout;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 /** End-to-end submission test of Beam jobs on a Flink cluster. */
 @SuppressWarnings({
@@ -56,6 +59,8 @@
 })
 public class FlinkSubmissionTest {
 
+  private static final Logger LOG = LoggerFactory.getLogger(FlinkSubmissionTest.class);
+
   @ClassRule public static final TemporaryFolder TEMP_FOLDER = new TemporaryFolder();
   private static final Map<String, String> ENV = System.getenv();
   private static final SecurityManager SECURITY_MANAGER = System.getSecurityManager();
@@ -66,14 +71,9 @@ public class FlinkSubmissionTest {
   /** Each test has a timeout of 60 seconds (for safety). */
   @Rule public Timeout timeout = new Timeout(60, TimeUnit.SECONDS);
 
-  /** Whether to run in streaming or batch translation mode. */
-  private static boolean streaming;
-
   /** Counter which keeps track of the number of jobs submitted. */
   private static int expectedNumberOfJobs;
 
-  public static boolean useDataStreamForBatch;
-
   @BeforeClass
   public static void beforeClass() throws Exception {
     Configuration config = new Configuration();
@@ -103,37 +103,36 @@ public static void afterClass() throws Exception {
 
   @Test
   public void testSubmissionBatch() throws Exception {
-    runSubmission(false, false);
+    runSubmission(false, false, false);
   }
 
   @Test
   public void testSubmissionBatchUseDataStream() throws Exception {
-    FlinkSubmissionTest.useDataStreamForBatch = true;
-    runSubmission(false, false);
+    runSubmission(false, false, true);
   }
 
   @Test
   public void testSubmissionStreaming() throws Exception {
-    runSubmission(false, true);
+    runSubmission(false, true, false);
   }
 
   @Test
   public void testDetachedSubmissionBatch() throws Exception {
-    runSubmission(true, false);
+    runSubmission(true, false, false);
   }
 
   @Test
   public void testDetachedSubmissionBatchUseDataStream() throws Exception {
-    FlinkSubmissionTest.useDataStreamForBatch = true;
-    runSubmission(true, false);
+    runSubmission(true, false, true);
   }
 
   @Test
   public void testDetachedSubmissionStreaming() throws Exception {
-    runSubmission(true, true);
+    runSubmission(true, true, false);
   }
 
-  private void runSubmission(boolean isDetached, boolean isStreaming) throws Exception {
+  private void runSubmission(boolean isDetached, boolean isStreaming, boolean useDataStreamForBatch)
+      throws Exception {
     PipelineOptions options = PipelineOptionsFactory.create();
     options.as(FlinkPipelineOptions.class).setStreaming(isStreaming);
     options.setTempLocation(TEMP_FOLDER.getRoot().getPath());
@@ -150,8 +149,16 @@ private void runSubmission(boolean isDetached, boolean isStreaming) throws Excep
         argsBuilder.add("-d");
       }
       argsBuilder.add(jarPath);
+      argsBuilder.add("--runner=flink");
+
+      if (isStreaming) {
+        argsBuilder.add("--streaming");
+      }
+
+      if (useDataStreamForBatch) {
+        argsBuilder.add("--useDataStreamForBatch");
+      }
 
-      FlinkSubmissionTest.streaming = isStreaming;
       FlinkSubmissionTest.expectedNumberOfJobs++;
       // Run end-to-end test
       CliFrontend.main(argsBuilder.build().toArray(new String[0]));
@@ -169,19 +176,21 @@ private void waitUntilJobIsCompleted() throws Exception {
       Collection<JobStatusMessage> allJobsStates = flinkCluster.listJobs().get();
       if (allJobsStates.size() == expectedNumberOfJobs
           && allJobsStates.stream()
-              .allMatch(jobStatus -> jobStatus.getJobState().name().equals("FINISHED"))) {
+              .allMatch(jobStatus -> jobStatus.getJobState().isTerminalState())) {
+        LOG.info(
+            "All job finished with statuses: {}",
+            allJobsStates.stream().map(j -> j.getJobState().name()).collect(Collectors.toList()));
         return;
       }
-      Thread.sleep(100);
+      Thread.sleep(50);
     }
   }
 
   /** The Flink program which is executed by the CliFrontend. */
   public static void main(String[] args) {
-    FlinkPipelineOptions options = FlinkPipelineOptions.defaults();
-    options.setUseDataStreamForBatch(useDataStreamForBatch);
+    FlinkPipelineOptions options =
+        PipelineOptionsFactory.fromArgs(args).withValidation().as(FlinkPipelineOptions.class);
     options.setRunner(FlinkRunner.class);
-    options.setStreaming(streaming);
     options.setParallelism(1);
     Pipeline p = Pipeline.create(options);
     p.apply(GenerateSequence.from(0).to(1));

From eaa08a54ec4fcdc729c7c7d185cc909de3be84ab Mon Sep 17 00:00:00 2001
From: jto <boudhevil@gmail.com>
Date: Wed, 16 Oct 2024 15:48:35 +0200
Subject: [PATCH 22/26] [Flink] Use a custom key type to better distribute load

---
 ...FlinkStreamingAggregationsTranslators.java | 291 +++++++++++++-----
 .../FlinkStreamingPipelineTranslator.java     |   6 +-
 ...nkStreamingPortablePipelineTranslator.java |  22 +-
 .../FlinkStreamingTransformTranslators.java   |  46 ++-
 .../beam/runners/flink/adapter/FlinkKey.java  |  71 +++++
 .../wrappers/streaming/DoFnOperator.java      |  12 +-
 .../ExecutableStageDoFnOperator.java          |  69 ++---
 ...ctor.java => KvToFlinkKeyKeySelector.java} |  23 +-
 ...ector.java => SdfFlinkKeyKeySelector.java} |  22 +-
 .../streaming/WorkItemKeySelector.java        |  20 +-
 .../streaming/io/DedupingOperator.java        |   8 +-
 .../streaming/state/FlinkStateInternals.java  |  46 +--
 .../runners/flink/adapter/FlinkKeyTest.java   |  80 +++++
 .../streaming/FlinkStateInternalsTest.java    |  24 +-
 .../wrappers/streaming/DoFnOperatorTest.java  |  97 +++---
 .../ExecutableStageDoFnOperatorTest.java      |  30 +-
 .../streaming/WindowDoFnOperatorTest.java     |  18 +-
 17 files changed, 574 insertions(+), 311 deletions(-)
 create mode 100644 runners/flink/src/main/java/org/apache/beam/runners/flink/adapter/FlinkKey.java
 rename runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/{KvToByteBufferKeySelector.java => KvToFlinkKeyKeySelector.java} (62%)
 rename runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/{SdfByteBufferKeySelector.java => SdfFlinkKeyKeySelector.java} (75%)
 create mode 100644 runners/flink/src/test/java/org/apache/beam/runners/flink/adapter/FlinkKeyTest.java

diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingAggregationsTranslators.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingAggregationsTranslators.java
index 4bfe1ba5472c..1579a3d4affa 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingAggregationsTranslators.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingAggregationsTranslators.java
@@ -17,18 +17,13 @@
  */
 package org.apache.beam.runners.flink;
 
-import java.nio.ByteBuffer;
-import java.util.ArrayList;
-import java.util.Collections;
-import java.util.HashMap;
-import java.util.List;
-import java.util.Map;
 import org.apache.beam.runners.core.KeyedWorkItem;
 import org.apache.beam.runners.core.SystemReduceFn;
 import org.apache.beam.runners.core.construction.SerializablePipelineOptions;
+import org.apache.beam.runners.flink.adapter.FlinkKey;
 import org.apache.beam.runners.flink.translation.types.CoderTypeInformation;
 import org.apache.beam.runners.flink.translation.wrappers.streaming.DoFnOperator;
-import org.apache.beam.runners.flink.translation.wrappers.streaming.KvToByteBufferKeySelector;
+import org.apache.beam.runners.flink.translation.wrappers.streaming.KvToFlinkKeyKeySelector;
 import org.apache.beam.runners.flink.translation.wrappers.streaming.PartialReduceBundleOperator;
 import org.apache.beam.runners.flink.translation.wrappers.streaming.SingletonKeyedWorkItemCoder;
 import org.apache.beam.runners.flink.translation.wrappers.streaming.WindowDoFnOperator;
@@ -38,7 +33,6 @@
 import org.apache.beam.sdk.coders.CoderRegistry;
 import org.apache.beam.sdk.coders.IterableCoder;
 import org.apache.beam.sdk.coders.KvCoder;
-import org.apache.beam.sdk.coders.ListCoder;
 import org.apache.beam.sdk.transforms.Combine;
 import org.apache.beam.sdk.transforms.CombineFnBase;
 import org.apache.beam.sdk.transforms.CombineWithContext;
@@ -53,43 +47,50 @@
 import org.apache.beam.sdk.values.TupleTag;
 import org.apache.beam.sdk.values.WindowingStrategy;
 import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.ImmutableList;
+import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.Iterables;
+import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.Lists;
+import org.apache.flink.api.common.functions.FlatMapFunction;
 import org.apache.flink.api.common.typeinfo.TypeInformation;
 import org.apache.flink.api.java.tuple.Tuple2;
 import org.apache.flink.streaming.api.datastream.DataStream;
 import org.apache.flink.streaming.api.datastream.KeyedStream;
 import org.apache.flink.streaming.api.datastream.SingleOutputStreamOperator;
 import org.apache.flink.streaming.api.transformations.TwoInputTransformation;
+import org.apache.flink.util.Collector;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
 
 public class FlinkStreamingAggregationsTranslators {
-  public static class ConcatenateAsIterable<T> extends Combine.CombineFn<T, List<T>, Iterable<T>> {
+  public static class ConcatenateAsIterable<T> extends Combine.CombineFn<T, Iterable<T>, Iterable<T>> {
     @Override
-    public List<T> createAccumulator() {
+    public Iterable<T> createAccumulator() {
       return new ArrayList<>();
     }
 
     @Override
-    public List<T> addInput(List<T> accumulator, T input) {
-      accumulator.add(input);
-      return accumulator;
+    public Iterable<T> addInput(Iterable<T> accumulator, T input) {
+      ArrayList<T> arr = Lists.newArrayList(accumulator);
+      arr.add(input);
+      return arr;
     }
 
     @Override
-    public List<T> mergeAccumulators(Iterable<List<T>> accumulators) {
-      List<T> result = createAccumulator();
-      for (List<T> accumulator : accumulators) {
-        result.addAll(accumulator);
-      }
-      return result;
+    public Iterable<T> mergeAccumulators(Iterable<Iterable<T>> accumulators) {
+      return Iterables.concat(accumulators);
     }
 
     @Override
-    public List<T> extractOutput(List<T> accumulator) {
+    public Iterable<T> extractOutput(Iterable<T> accumulator) {
       return accumulator;
     }
 
     @Override
-    public Coder<List<T>> getAccumulatorCoder(CoderRegistry registry, Coder<T> inputCoder) {
-      return ListCoder.of(inputCoder);
+    public Coder<Iterable<T>> getAccumulatorCoder(CoderRegistry registry, Coder<T> inputCoder) {
+      return IterableCoder.of(inputCoder);
     }
 
     @Override
@@ -214,7 +215,7 @@ WindowDoFnOperator<K, InputAccumT, OutputAccumT> getWindowedAggregateDoFnOperato
 
     // Key selector
     WorkItemKeySelector<K, InputAccumT> workItemKeySelector =
-        new WorkItemKeySelector<>(keyCoder, serializablePipelineOptions);
+        new WorkItemKeySelector<>(keyCoder);
 
     return new WindowDoFnOperator<>(
         reduceFn,
@@ -255,6 +256,179 @@ WindowDoFnOperator<K, InputAccumT, OutputAccumT> getWindowedAggregateDoFnOperato
         context, transform, inputKvCoder, outputCoder, reduceFn, sideInputTagMapping, sideInputs);
   }
 
+  private static class FlattenIterable<K, InputT>
+      implements FlatMapFunction<WindowedValue<KV<K, Iterable<Iterable<InputT>>>>, WindowedValue<KV<K, Iterable<InputT>>>> {
+    @Override
+    public void flatMap(
+        WindowedValue<KV<K, Iterable<Iterable<InputT>>>> w,
+        Collector<WindowedValue<KV<K, Iterable<InputT>>>> collector) throws Exception {
+      WindowedValue<KV<K, Iterable<InputT>>> flattened = w.withValue(
+          KV.of(
+              w.getValue().getKey(),
+              Iterables.concat(w.getValue().getValue())));
+      collector.collect(flattened);
+    }
+  }
+
+  public static <K, InputT, AccumT, OutputT>
+    SingleOutputStreamOperator<WindowedValue<KV<K, OutputT>>> getBatchCombinePerKeyOperator(
+        FlinkStreamingTranslationContext context,
+        PCollection<KV<K, InputT>> input,
+        Map<Integer, PCollectionView<?>> sideInputTagMapping,
+        List<PCollectionView<?>> sideInputs,
+        Coder<WindowedValue<KV<K, AccumT>>> windowedAccumCoder,
+        CombineFnBase.GlobalCombineFn<InputT, AccumT, ?> combineFn,
+        WindowDoFnOperator<K, AccumT, OutputT> finalDoFnOperator,
+        TypeInformation<WindowedValue<KV<K, OutputT>>> outputTypeInfo){
+
+    String fullName = FlinkStreamingTransformTranslators.getCurrentTransformName(context);
+    DataStream<WindowedValue<KV<K, InputT>>> inputDataStream = context.getInputDataStream(input);
+    KvCoder<K, InputT> inputKvCoder = (KvCoder<K, InputT>) input.getCoder();
+
+    SerializablePipelineOptions serializablePipelineOptions =
+        new SerializablePipelineOptions(context.getPipelineOptions());
+
+    TupleTag<KV<K, AccumT>> mainTag = new TupleTag<>("main output");
+    String partialName = "Combine: " + fullName;
+
+    KvToFlinkKeyKeySelector<K, AccumT> accumKeySelector =
+        new KvToFlinkKeyKeySelector<>(inputKvCoder.getKeyCoder());
+
+    CoderTypeInformation<WindowedValue<KV<K, AccumT>>> partialTypeInfo =
+        new CoderTypeInformation<>(windowedAccumCoder, context.getPipelineOptions());
+
+    PartialReduceBundleOperator<K, InputT, ?, AccumT> partialDoFnOperator =
+        new PartialReduceBundleOperator<>(
+            combineFn,
+            fullName,
+            context.getWindowedInputCoder(input),
+            mainTag,
+            Collections.emptyList(),
+            new DoFnOperator.MultiOutputOutputManagerFactory<>(
+                mainTag, windowedAccumCoder, serializablePipelineOptions),
+            input.getWindowingStrategy(),
+            sideInputTagMapping,
+            sideInputs,
+            context.getPipelineOptions());
+
+    if (sideInputs.isEmpty()) {
+      return inputDataStream
+          .transform(partialName, partialTypeInfo, partialDoFnOperator)
+          .uid(partialName).name(partialName)
+          .keyBy(accumKeySelector)
+          .transform(fullName, outputTypeInfo, finalDoFnOperator)
+          .uid(fullName).name(fullName);
+    } else {
+
+      Tuple2<Map<Integer, PCollectionView<?>>, DataStream<RawUnionValue>> transformSideInputs =
+          FlinkStreamingTransformTranslators.transformSideInputs(sideInputs, context);
+
+      TwoInputTransformation<
+          WindowedValue<KV<K, InputT>>, RawUnionValue, WindowedValue<KV<K, AccumT>>> rawPartialFlinkTransform =
+          new TwoInputTransformation<>(
+              inputDataStream.getTransformation(),
+              transformSideInputs.f1.broadcast().getTransformation(),
+              partialName,
+              partialDoFnOperator,
+              partialTypeInfo,
+              inputDataStream.getParallelism());
+
+      SingleOutputStreamOperator<WindowedValue<KV<K, AccumT>>> partialyCombinedStream =
+          new SingleOutputStreamOperator<WindowedValue<KV<K, AccumT>>>(
+              inputDataStream.getExecutionEnvironment(),
+              rawPartialFlinkTransform) {}; // we have to cheat around the ctor being protected
+
+        inputDataStream.getExecutionEnvironment().addOperator(rawPartialFlinkTransform);
+
+        return buildTwoInputStream(
+            partialyCombinedStream.keyBy(accumKeySelector),
+            transformSideInputs.f1,
+            fullName,
+            finalDoFnOperator,
+            outputTypeInfo);
+    }
+  }
+
+  /**
+   * Creates a two-steps GBK operation. Elements are first aggregated locally to save on serialized size since in batch
+   * it's very likely that all the elements will be within the same window and pane.
+   * The only difference with batchCombinePerKey is the nature of the SystemReduceFn used. It uses SystemReduceFn.buffering()
+   * instead of SystemReduceFn.combining() so that new element can simply be appended without accessing the existing state.
+   */
+  public static <K, InputT> SingleOutputStreamOperator<WindowedValue<KV<K, Iterable<InputT>>>> batchGroupByKey(
+      FlinkStreamingTranslationContext context,
+      PTransform<PCollection<KV<K, InputT>>, PCollection<KV<K, Iterable<InputT>>>> transform) {
+
+    Map<Integer, PCollectionView<?>> sideInputTagMapping = new HashMap<>();
+    List<PCollectionView<?>> sideInputs = Collections.emptyList();
+
+    PCollection<KV<K, InputT>> input = context.getInput(transform);
+    KvCoder<K, InputT> inputKvCoder = (KvCoder<K, InputT>) input.getCoder();
+
+    SerializablePipelineOptions serializablePipelineOptions =
+        new SerializablePipelineOptions(context.getPipelineOptions());
+
+    TypeInformation<WindowedValue<KV<K, Iterable<InputT>>>> outputTypeInfo =
+        context.getTypeInfo(context.getOutput(transform));
+
+    Coder<Iterable<InputT>> accumulatorCoder = IterableCoder.of(inputKvCoder.getValueCoder());
+    KvCoder<K, Iterable<InputT>> accumKvCoder = KvCoder.of(inputKvCoder.getKeyCoder(), accumulatorCoder);
+
+    Coder<WindowedValue<KV<K, Iterable<InputT>>>> windowedAccumCoder =
+        WindowedValue.getFullCoder(
+            accumKvCoder, input.getWindowingStrategy().getWindowFn().windowCoder());
+
+    Coder<WindowedValue<KV<K, Iterable<Iterable<InputT>>>>> outputCoder =
+        WindowedValue.getFullCoder(
+            KvCoder.of(inputKvCoder.getKeyCoder(), IterableCoder.of(accumulatorCoder)) , input.getWindowingStrategy().getWindowFn().windowCoder());
+
+    TypeInformation<WindowedValue<KV<K, Iterable<Iterable<InputT>>>>> accumulatedTypeInfo =
+        new CoderTypeInformation<>(
+          WindowedValue.getFullCoder(
+              KvCoder.of(inputKvCoder.getKeyCoder(), IterableCoder.of(IterableCoder.of(inputKvCoder.getValueCoder()))), input.getWindowingStrategy().getWindowFn().windowCoder()),
+            serializablePipelineOptions);
+
+    // final aggregation
+    WindowDoFnOperator<K, Iterable<InputT>, Iterable<Iterable<InputT>>> finalDoFnOperator =
+          getWindowedAccumulateDoFnOperator(
+              context,
+              transform,
+              accumKvCoder,
+              outputCoder,
+              sideInputTagMapping,
+              sideInputs);
+
+    return
+        getBatchCombinePerKeyOperator(
+          context,
+          input,
+          sideInputTagMapping,
+          sideInputs,
+          windowedAccumCoder,
+          new ConcatenateAsIterable<>(),
+          finalDoFnOperator,
+          accumulatedTypeInfo
+      )
+      .flatMap(new FlattenIterable<>(), outputTypeInfo)
+      .name("concatenate");
+  }
+
+  private static <InputT, K> WindowDoFnOperator<K, Iterable<InputT>, Iterable<Iterable<InputT>>> getWindowedAccumulateDoFnOperator(
+      FlinkStreamingTranslationContext context,
+      PTransform<PCollection<KV<K,InputT>>, PCollection<KV<K, Iterable<InputT>>>> transform,
+      KvCoder<K, Iterable<InputT>> accumKvCoder,
+      Coder<WindowedValue<KV<K, Iterable<Iterable<InputT>>>>> outputCoder,
+      Map<Integer, PCollectionView<?>> sideInputTagMapping,
+      List<PCollectionView<?>> sideInputs) {
+
+      // Combining fn
+    SystemReduceFn<K, Iterable<InputT>, Iterable<Iterable<InputT>>, Iterable<Iterable<InputT>>, BoundedWindow> reduceFn =
+        SystemReduceFn.buffering(accumKvCoder.getValueCoder());
+
+    return getWindowedAggregateDoFnOperator(
+        context, transform, accumKvCoder, outputCoder, reduceFn, sideInputTagMapping, sideInputs);
+  }
+
   public static <K, InputT, AccumT, OutputT>
       SingleOutputStreamOperator<WindowedValue<KV<K, OutputT>>> batchCombinePerKey(
           FlinkStreamingTranslationContext context,
@@ -267,18 +441,16 @@ SingleOutputStreamOperator<WindowedValue<KV<K, OutputT>>> batchCombinePerKey(
     KvCoder<K, AccumT> accumKvCoder;
 
     PCollection<KV<K, InputT>> input = context.getInput(transform);
-    String fullName = FlinkStreamingTransformTranslators.getCurrentTransformName(context);
-    DataStream<WindowedValue<KV<K, InputT>>> inputDataStream = context.getInputDataStream(input);
     KvCoder<K, InputT> inputKvCoder = (KvCoder<K, InputT>) input.getCoder();
-    Coder<WindowedValue<KV<K, OutputT>>> outputCoder =
-        context.getWindowedInputCoder(context.getOutput(transform));
-    SerializablePipelineOptions serializablePipelineOptions =
-        new SerializablePipelineOptions(context.getPipelineOptions());
     TypeInformation<WindowedValue<KV<K, OutputT>>> outputTypeInfo =
         context.getTypeInfo(context.getOutput(transform));
 
+    Coder<WindowedValue<KV<K, OutputT>>> outputCoder =
+        context.getWindowedInputCoder(context.getOutput(transform));
+
+    Coder<AccumT> accumulatorCoder;
     try {
-      Coder<AccumT> accumulatorCoder =
+      accumulatorCoder =
           combineFn.getAccumulatorCoder(
               input.getPipeline().getCoderRegistry(), inputKvCoder.getValueCoder());
 
@@ -291,29 +463,6 @@ SingleOutputStreamOperator<WindowedValue<KV<K, OutputT>>> batchCombinePerKey(
       throw new RuntimeException(e);
     }
 
-    TupleTag<KV<K, AccumT>> mainTag = new TupleTag<>("main output");
-
-    PartialReduceBundleOperator<K, InputT, OutputT, AccumT> partialDoFnOperator =
-        new PartialReduceBundleOperator<>(
-            combineFn,
-            fullName,
-            context.getWindowedInputCoder(input),
-            mainTag,
-            Collections.emptyList(),
-            new DoFnOperator.MultiOutputOutputManagerFactory<>(
-                mainTag, windowedAccumCoder, serializablePipelineOptions),
-            input.getWindowingStrategy(),
-            sideInputTagMapping,
-            sideInputs,
-            context.getPipelineOptions());
-
-    String partialName = "Combine: " + fullName;
-    CoderTypeInformation<WindowedValue<KV<K, AccumT>>> partialTypeInfo =
-        new CoderTypeInformation<>(windowedAccumCoder, context.getPipelineOptions());
-
-    KvToByteBufferKeySelector<K, AccumT> accumKeySelector =
-        new KvToByteBufferKeySelector<>(inputKvCoder.getKeyCoder(), serializablePipelineOptions);
-
     // final aggregation from AccumT to OutputT
     WindowDoFnOperator<K, AccumT, OutputT> finalDoFnOperator =
         getWindowedAggregateDoFnOperator(
@@ -325,30 +474,16 @@ SingleOutputStreamOperator<WindowedValue<KV<K, OutputT>>> batchCombinePerKey(
             sideInputTagMapping,
             sideInputs);
 
-    if (sideInputs.isEmpty()) {
-      return inputDataStream
-          .transform(partialName, partialTypeInfo, partialDoFnOperator)
-          .uid(partialName)
-          .keyBy(accumKeySelector)
-          .transform(fullName, outputTypeInfo, finalDoFnOperator)
-          .uid(fullName);
-    } else {
-      Tuple2<Map<Integer, PCollectionView<?>>, DataStream<RawUnionValue>> transformSideInputs =
-          FlinkStreamingTransformTranslators.transformSideInputs(sideInputs, context);
-
-      KeyedStream<WindowedValue<KV<K, AccumT>>, ByteBuffer> keyedStream =
-          inputDataStream
-              .transform(partialName, partialTypeInfo, partialDoFnOperator)
-              .uid(partialName)
-              .keyBy(accumKeySelector);
-
-      return buildTwoInputStream(
-          keyedStream,
-          transformSideInputs.f1,
-          transform.getName(),
-          finalDoFnOperator,
-          outputTypeInfo);
-    }
+    return getBatchCombinePerKeyOperator(
+        context,
+        context.getInput(transform),
+        sideInputTagMapping,
+        sideInputs,
+        windowedAccumCoder,
+        combineFn,
+        finalDoFnOperator,
+        outputTypeInfo
+    );
   }
 
   @SuppressWarnings({
@@ -356,7 +491,7 @@ SingleOutputStreamOperator<WindowedValue<KV<K, OutputT>>> batchCombinePerKey(
   })
   public static <K, InputT, OutputT>
       SingleOutputStreamOperator<WindowedValue<KV<K, OutputT>>> buildTwoInputStream(
-          KeyedStream<WindowedValue<KV<K, InputT>>, ByteBuffer> keyedStream,
+          KeyedStream<WindowedValue<KV<K, InputT>>, FlinkKey> keyedStream,
           DataStream<RawUnionValue> sideInputStream,
           String name,
           WindowDoFnOperator<K, InputT, OutputT> operator,
diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingPipelineTranslator.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingPipelineTranslator.java
index 3ed00a3c5ef2..8f0e6db26dab 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingPipelineTranslator.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingPipelineTranslator.java
@@ -20,7 +20,6 @@
 import static org.apache.beam.sdk.util.construction.PTransformTranslation.WRITE_FILES_TRANSFORM_URN;
 
 import java.io.IOException;
-import java.nio.ByteBuffer;
 import java.util.Arrays;
 import java.util.HashMap;
 import java.util.List;
@@ -28,7 +27,8 @@
 import java.util.Objects;
 import java.util.concurrent.ThreadLocalRandom;
 import java.util.concurrent.TimeUnit;
-import org.apache.beam.runners.flink.translation.wrappers.streaming.FlinkKeyUtils;
+
+import org.apache.beam.runners.flink.adapter.FlinkKey;
 import org.apache.beam.sdk.Pipeline;
 import org.apache.beam.sdk.coders.Coder;
 import org.apache.beam.sdk.coders.ShardedKeyCoder;
@@ -399,7 +399,7 @@ private Map<Integer, ShardedKey<Integer>> generateShardedKeys(int key, int shard
 
           // create effective key in the same way Beam/Flink will do so we can see if it gets
           // allocated to the partition we want
-          ByteBuffer effectiveKey = FlinkKeyUtils.encodeKey(shk, shardedKeyCoder);
+          FlinkKey effectiveKey = FlinkKey.of(shk, shardedKeyCoder);
 
           int partition =
               KeyGroupRangeAssignment.assignKeyToParallelOperator(
diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingPortablePipelineTranslator.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingPortablePipelineTranslator.java
index e7244bf982d0..901ab1c672dc 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingPortablePipelineTranslator.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingPortablePipelineTranslator.java
@@ -27,7 +27,6 @@
 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.google.auto.service.AutoService;
 import java.io.IOException;
-import java.nio.ByteBuffer;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashMap;
@@ -41,14 +40,15 @@
 import org.apache.beam.runners.core.KeyedWorkItem;
 import org.apache.beam.runners.core.SystemReduceFn;
 import org.apache.beam.runners.core.construction.SerializablePipelineOptions;
+import org.apache.beam.runners.flink.adapter.FlinkKey;
 import org.apache.beam.runners.flink.translation.functions.FlinkExecutableStageContextFactory;
 import org.apache.beam.runners.flink.translation.functions.ImpulseSourceFunction;
 import org.apache.beam.runners.flink.translation.types.CoderTypeInformation;
 import org.apache.beam.runners.flink.translation.wrappers.SourceInputFormat;
 import org.apache.beam.runners.flink.translation.wrappers.streaming.DoFnOperator;
 import org.apache.beam.runners.flink.translation.wrappers.streaming.ExecutableStageDoFnOperator;
-import org.apache.beam.runners.flink.translation.wrappers.streaming.KvToByteBufferKeySelector;
-import org.apache.beam.runners.flink.translation.wrappers.streaming.SdfByteBufferKeySelector;
+import org.apache.beam.runners.flink.translation.wrappers.streaming.KvToFlinkKeyKeySelector;
+import org.apache.beam.runners.flink.translation.wrappers.streaming.SdfFlinkKeyKeySelector;
 import org.apache.beam.runners.flink.translation.wrappers.streaming.SingletonKeyedWorkItemCoder;
 import org.apache.beam.runners.flink.translation.wrappers.streaming.WindowDoFnOperator;
 import org.apache.beam.runners.flink.translation.wrappers.streaming.WorkItemKeySelector;
@@ -431,15 +431,11 @@ private <K, V> SingleOutputStreamOperator<WindowedValue<KV<K, Iterable<V>>>> add
         WindowedValue.getFullCoder(workItemCoder, windowingStrategy.getWindowFn().windowCoder());
 
     WorkItemKeySelector<K, V> keySelector =
-        new WorkItemKeySelector<>(
-            inputElementCoder.getKeyCoder(),
-            new SerializablePipelineOptions(context.getPipelineOptions()));
+        new WorkItemKeySelector<>(inputElementCoder.getKeyCoder());
 
-    KeyedStream<WindowedValue<KV<K, V>>, ByteBuffer> keyedWorkItemStream =
+    KeyedStream<WindowedValue<KV<K, V>>, FlinkKey> keyedWorkItemStream =
         inputDataStream.keyBy(
-            new KvToByteBufferKeySelector(
-                inputElementCoder.getKeyCoder(),
-                new SerializablePipelineOptions(context.getPipelineOptions())));
+            new KvToFlinkKeyKeySelector(inputElementCoder.getKeyCoder()));
 
     SystemReduceFn<K, V, Iterable<V>, Iterable<V>, BoundedWindow> reduceFn =
         SystemReduceFn.buffering(inputElementCoder.getValueCoder());
@@ -834,8 +830,7 @@ private <InputT, OutputT> void translateExecutableStage(
       if (stateful) {
         keyCoder = ((KvCoder) valueCoder).getKeyCoder();
         keySelector =
-            new KvToByteBufferKeySelector(
-                keyCoder, new SerializablePipelineOptions(context.getPipelineOptions()));
+            new KvToFlinkKeyKeySelector(keyCoder);
       } else {
         // For an SDF, we know that the input element should be
         // KV<KV<element, KV<restriction, watermarkState>>, size>. We are going to use the element
@@ -850,8 +845,7 @@ private <InputT, OutputT> void translateExecutableStage(
         }
         keyCoder = ((KvCoder) ((KvCoder) valueCoder).getKeyCoder()).getKeyCoder();
         keySelector =
-            new SdfByteBufferKeySelector(
-                keyCoder, new SerializablePipelineOptions(context.getPipelineOptions()));
+            new SdfFlinkKeyKeySelector(keyCoder);
       }
       inputDataStream = inputDataStream.keyBy(keySelector);
     }
diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingTransformTranslators.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingTransformTranslators.java
index f8401efb343a..35a08eb54115 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingTransformTranslators.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingTransformTranslators.java
@@ -33,11 +33,12 @@
 import org.apache.beam.runners.core.SplittableParDoViaKeyedWorkItems;
 import org.apache.beam.runners.core.SystemReduceFn;
 import org.apache.beam.runners.core.construction.SerializablePipelineOptions;
+import org.apache.beam.runners.flink.adapter.FlinkKey;
 import org.apache.beam.runners.flink.translation.functions.FlinkAssignWindows;
 import org.apache.beam.runners.flink.translation.functions.ImpulseSourceFunction;
 import org.apache.beam.runners.flink.translation.types.CoderTypeInformation;
 import org.apache.beam.runners.flink.translation.wrappers.streaming.DoFnOperator;
-import org.apache.beam.runners.flink.translation.wrappers.streaming.KvToByteBufferKeySelector;
+import org.apache.beam.runners.flink.translation.wrappers.streaming.KvToFlinkKeyKeySelector;
 import org.apache.beam.runners.flink.translation.wrappers.streaming.SingletonKeyedWorkItem;
 import org.apache.beam.runners.flink.translation.wrappers.streaming.SingletonKeyedWorkItemCoder;
 import org.apache.beam.runners.flink.translation.wrappers.streaming.SplittableDoFnOperator;
@@ -106,6 +107,7 @@
 import org.apache.flink.api.java.tuple.Tuple2;
 import org.apache.flink.api.java.typeutils.GenericTypeInfo;
 import org.apache.flink.api.java.typeutils.ResultTypeQueryable;
+import org.apache.flink.api.java.typeutils.ValueTypeInfo;
 import org.apache.flink.configuration.Configuration;
 import org.apache.flink.runtime.state.CheckpointListener;
 import org.apache.flink.runtime.state.FunctionInitializationContext;
@@ -262,17 +264,17 @@ public void translateNode(
   }
 
   static class ValueWithRecordIdKeySelector<T>
-      implements KeySelector<WindowedValue<ValueWithRecordId<T>>, ByteBuffer>,
-          ResultTypeQueryable<ByteBuffer> {
+      implements KeySelector<WindowedValue<ValueWithRecordId<T>>, FlinkKey>,
+          ResultTypeQueryable<FlinkKey> {
 
     @Override
-    public ByteBuffer getKey(WindowedValue<ValueWithRecordId<T>> value) throws Exception {
-      return ByteBuffer.wrap(value.getValue().getId());
+    public FlinkKey getKey(WindowedValue<ValueWithRecordId<T>> value) throws Exception {
+      return FlinkKey.of(ByteBuffer.wrap(value.getValue().getId()));
     }
 
     @Override
-    public TypeInformation<ByteBuffer> getProducedType() {
-      return new GenericTypeInfo<>(ByteBuffer.class);
+    public TypeInformation<FlinkKey> getProducedType() {
+      return ValueTypeInfo.of(FlinkKey.class);
     }
   }
 
@@ -590,8 +592,7 @@ static <InputT, OutputT> void translateParDo(
         // that it is also keyed
         keyCoder = ((KvCoder) input.getCoder()).getKeyCoder();
         keySelector =
-            new KvToByteBufferKeySelector(
-                keyCoder, new SerializablePipelineOptions(context.getPipelineOptions()));
+            new KvToFlinkKeyKeySelector<>(keyCoder);
         final PTransform<?, PCollection<InputT>> producer = context.getProducer(input);
         final String previousUrn =
             producer != null
@@ -609,8 +610,7 @@ static <InputT, OutputT> void translateParDo(
         // we know that it is keyed on byte[]
         keyCoder = ByteArrayCoder.of();
         keySelector =
-            new WorkItemKeySelector<>(
-                keyCoder, new SerializablePipelineOptions(context.getPipelineOptions()));
+            new WorkItemKeySelector<>(keyCoder);
         stateful = true;
       }
 
@@ -963,16 +963,13 @@ public void translateNode(
       // Pre-aggregate before shuffle similar to group combine
       if (!context.isStreaming()) {
         outDataStream =
-            FlinkStreamingAggregationsTranslators.batchCombinePerKeyNoSideInputs(
+            FlinkStreamingAggregationsTranslators.batchGroupByKey(
                 context,
-                transform,
-                new FlinkStreamingAggregationsTranslators.ConcatenateAsIterable<>());
+                transform);
       } else {
         // No pre-aggregation in Streaming mode.
-        KvToByteBufferKeySelector<K, InputT> keySelector =
-            new KvToByteBufferKeySelector<>(
-                inputKvCoder.getKeyCoder(),
-                new SerializablePipelineOptions(context.getPipelineOptions()));
+        KvToFlinkKeyKeySelector<K, InputT> keySelector =
+            new KvToFlinkKeyKeySelector<>(inputKvCoder.getKeyCoder());
 
         Coder<WindowedValue<KV<K, Iterable<InputT>>>> outputCoder =
             WindowedValue.getFullCoder(
@@ -1039,9 +1036,6 @@ public void translateNode(
 
       DataStream<WindowedValue<KV<K, InputT>>> inputDataStream = context.getInputDataStream(input);
 
-      SerializablePipelineOptions serializablePipelineOptions =
-          new SerializablePipelineOptions(context.getPipelineOptions());
-
       @SuppressWarnings("unchecked")
       GlobalCombineFn<InputT, ?, OutputT> combineFn = ((Combine.PerKey) transform).getFn();
 
@@ -1051,9 +1045,9 @@ public void translateNode(
       @SuppressWarnings("unchecked")
       List<PCollectionView<?>> sideInputs = ((Combine.PerKey) transform).getSideInputs();
 
-      KeyedStream<WindowedValue<KV<K, InputT>>, ByteBuffer> keyedStream =
+      KeyedStream<WindowedValue<KV<K, InputT>>, FlinkKey> keyedStream =
           inputDataStream.keyBy(
-              new KvToByteBufferKeySelector<>(keyCoder, serializablePipelineOptions));
+              new KvToFlinkKeyKeySelector<>(keyCoder));
 
       if (sideInputs.isEmpty()) {
         SingleOutputStreamOperator<WindowedValue<KV<K, OutputT>>> outDataStream;
@@ -1152,11 +1146,9 @@ public void translateNode(
               .returns(workItemTypeInfo)
               .name("ToKeyedWorkItem");
 
-      KeyedStream<WindowedValue<KeyedWorkItem<K, InputT>>, ByteBuffer> keyedWorkItemStream =
+      KeyedStream<WindowedValue<KeyedWorkItem<K, InputT>>, FlinkKey> keyedWorkItemStream =
           workItemStream.keyBy(
-              new WorkItemKeySelector<>(
-                  inputKvCoder.getKeyCoder(),
-                  new SerializablePipelineOptions(context.getPipelineOptions())));
+              new WorkItemKeySelector<>(inputKvCoder.getKeyCoder()));
 
       context.setOutputDataStream(context.getOutput(transform), keyedWorkItemStream);
     }
diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/adapter/FlinkKey.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/adapter/FlinkKey.java
new file mode 100644
index 000000000000..637b4cb3696e
--- /dev/null
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/adapter/FlinkKey.java
@@ -0,0 +1,71 @@
+package org.apache.beam.runners.flink.adapter;
+
+import org.apache.beam.runners.flink.translation.types.CoderTypeSerializer;
+import org.apache.beam.runners.flink.translation.wrappers.streaming.FlinkKeyUtils;
+import org.apache.beam.sdk.coders.ByteArrayCoder;
+import org.apache.beam.sdk.coders.Coder;
+import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.hash.Hashing;
+import org.apache.flink.core.memory.DataInputView;
+import org.apache.flink.core.memory.DataOutputView;
+import org.apache.flink.types.Value;
+
+import javax.annotation.Nullable;
+import java.io.IOException;
+import java.nio.ByteBuffer;
+
+import static org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.base.Preconditions.checkNotNull;
+
+public class FlinkKey implements Value {
+
+  private final CoderTypeSerializer<byte[]> serializer;
+
+  @SuppressWarnings("initialization.fields.uninitialized")
+  private ByteBuffer underlying;
+
+  public FlinkKey() {
+    this.serializer = new CoderTypeSerializer<>(ByteArrayCoder.of(), false);
+  }
+
+  private FlinkKey(ByteBuffer underlying) {
+    this();
+    this.underlying = underlying;
+  }
+
+  public ByteBuffer getSerializedKey() {
+    return underlying;
+  }
+
+  public static FlinkKey of(ByteBuffer bytes) {
+    return new FlinkKey(bytes);
+  }
+
+  public static <K> FlinkKey of(K key, Coder<K> coder) {
+    return new FlinkKey(FlinkKeyUtils.encodeKey(key, coder));
+  }
+
+  @Override
+  public void write(DataOutputView out) throws IOException {
+    checkNotNull(underlying);
+    serializer.serialize(underlying.array(), out);
+  }
+
+  @Override
+  public void read(DataInputView in) throws IOException {
+    this.underlying = ByteBuffer.wrap(serializer.deserialize(in));
+  }
+
+  public <K> K getKey(Coder<K> coder) {
+    return FlinkKeyUtils.decodeKey(underlying, coder);
+  }
+
+  @Override
+  public int hashCode() {
+//    return underlying.hashCode();
+    return Hashing.murmur3_128().hashBytes(underlying.array()).asInt();
+  }
+
+  @Override
+  public boolean equals(@Nullable Object obj) {
+    return obj instanceof FlinkKey && ((FlinkKey) obj).underlying.equals(underlying);
+  }
+}
diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/DoFnOperator.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/DoFnOperator.java
index 5c6471ee9c23..98519cd508ba 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/DoFnOperator.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/DoFnOperator.java
@@ -24,7 +24,6 @@
 import java.io.InputStream;
 import java.io.OutputStream;
 import java.io.Serializable;
-import java.nio.ByteBuffer;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
@@ -57,6 +56,7 @@
 import org.apache.beam.runners.core.TimerInternals.TimerData;
 import org.apache.beam.runners.core.construction.SerializablePipelineOptions;
 import org.apache.beam.runners.flink.FlinkPipelineOptions;
+import org.apache.beam.runners.flink.adapter.FlinkKey;
 import org.apache.beam.runners.flink.metrics.DoFnRunnerWithMetricsUpdate;
 import org.apache.beam.runners.flink.metrics.FlinkMetricContainer;
 import org.apache.beam.runners.flink.translation.types.CoderTypeSerializer;
@@ -149,7 +149,7 @@ public class DoFnOperator<PreInputT, InputT, OutputT>
     extends AbstractStreamOperator<WindowedValue<OutputT>>
     implements OneInputStreamOperator<WindowedValue<PreInputT>, WindowedValue<OutputT>>,
         TwoInputStreamOperator<WindowedValue<PreInputT>, RawUnionValue, WindowedValue<OutputT>>,
-        Triggerable<ByteBuffer, TimerData> {
+        Triggerable<FlinkKey, TimerData> {
 
   private static final Logger LOG = LoggerFactory.getLogger(DoFnOperator.class);
   private final boolean isStreaming;
@@ -1146,19 +1146,19 @@ public void notifyCheckpointComplete(long checkpointId) throws Exception {
   }
 
   @Override
-  public void onEventTime(InternalTimer<ByteBuffer, TimerData> timer) {
+  public void onEventTime(InternalTimer<FlinkKey, TimerData> timer) {
     checkInvokeStartBundle();
     fireTimerInternal(timer.getKey(), timer.getNamespace());
   }
 
   @Override
-  public void onProcessingTime(InternalTimer<ByteBuffer, TimerData> timer) {
+  public void onProcessingTime(InternalTimer<FlinkKey, TimerData> timer) {
     checkInvokeStartBundle();
     fireTimerInternal(timer.getKey(), timer.getNamespace());
   }
 
   // allow overriding this in ExecutableStageDoFnOperator to set the key context
-  protected void fireTimerInternal(ByteBuffer key, TimerData timerData) {
+  protected void fireTimerInternal(FlinkKey key, TimerData timerData) {
     long oldHold = keyCoder != null ? keyedStateInternals.minWatermarkHoldMs() : -1L;
     fireTimer(timerData);
     emitWatermarkIfHoldChanged(oldHold);
@@ -1533,7 +1533,7 @@ void processPendingProcessingTimeTimers() {
         keyedStateBackend.setCurrentKey(internalTimer.getKey());
         TimerData timer = internalTimer.getNamespace();
         checkInvokeStartBundle();
-        fireTimerInternal((ByteBuffer) internalTimer.getKey(), timer);
+        fireTimerInternal((FlinkKey) internalTimer.getKey(), timer);
       }
     }
 
diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/ExecutableStageDoFnOperator.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/ExecutableStageDoFnOperator.java
index 5a7e25299ff7..c02d7d9c99ea 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/ExecutableStageDoFnOperator.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/ExecutableStageDoFnOperator.java
@@ -24,7 +24,6 @@
 
 import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
 import java.io.IOException;
-import java.nio.ByteBuffer;
 import java.util.ArrayDeque;
 import java.util.Arrays;
 import java.util.Collection;
@@ -59,6 +58,7 @@
 import org.apache.beam.runners.core.TimerInternals;
 import org.apache.beam.runners.core.TimerInternalsFactory;
 import org.apache.beam.runners.core.construction.SerializablePipelineOptions;
+import org.apache.beam.runners.flink.adapter.FlinkKey;
 import org.apache.beam.runners.flink.translation.functions.FlinkExecutableStageContextFactory;
 import org.apache.beam.runners.flink.translation.types.CoderTypeSerializer;
 import org.apache.beam.runners.flink.translation.utils.Locker;
@@ -369,17 +369,17 @@ static class BagUserStateFactory<V, W extends BoundedWindow>
       implements StateRequestHandlers.BagUserStateHandlerFactory<ByteString, V, W> {
 
     private final StateInternals stateInternals;
-    private final KeyedStateBackend<ByteBuffer> keyedStateBackend;
+    private final KeyedStateBackend<FlinkKey> keyedStateBackend;
     /** Lock to hold whenever accessing the state backend. */
     private final Lock stateBackendLock;
     /** For debugging: The key coder used by the Runner. */
     private final @Nullable Coder runnerKeyCoder;
     /** For debugging: Same as keyedStateBackend but upcasted, to access key group meta info. */
-    private final @Nullable AbstractKeyedStateBackend<ByteBuffer> keyStateBackendWithKeyGroupInfo;
+    private final @Nullable AbstractKeyedStateBackend<FlinkKey> keyStateBackendWithKeyGroupInfo;
 
     BagUserStateFactory(
         StateInternals stateInternals,
-        KeyedStateBackend<ByteBuffer> keyedStateBackend,
+        KeyedStateBackend<FlinkKey> keyedStateBackend,
         Lock stateBackendLock,
         @Nullable Coder runnerKeyCoder) {
       this.stateInternals = stateInternals;
@@ -389,7 +389,7 @@ static class BagUserStateFactory<V, W extends BoundedWindow>
         // This will always succeed, unless a custom state backend is used which does not extend
         // AbstractKeyedStateBackend. This is unlikely but we should still consider this case.
         this.keyStateBackendWithKeyGroupInfo =
-            (AbstractKeyedStateBackend<ByteBuffer>) keyedStateBackend;
+            (AbstractKeyedStateBackend<FlinkKey>) keyedStateBackend;
       } else {
         this.keyStateBackendWithKeyGroupInfo = null;
       }
@@ -417,7 +417,7 @@ public Iterable<V> get(ByteString key, W window) {
                   "State get for {} {} {} {}",
                   pTransformId,
                   userStateId,
-                  Arrays.toString(keyedStateBackend.getCurrentKey().array()),
+                  Arrays.toString(keyedStateBackend.getCurrentKey().getSerializedKey().array()),
                   window);
             }
             BagState<V> bagState =
@@ -437,7 +437,7 @@ public void append(ByteString key, W window, Iterator<V> values) {
                   "State append for {} {} {} {}",
                   pTransformId,
                   userStateId,
-                  Arrays.toString(keyedStateBackend.getCurrentKey().array()),
+                  Arrays.toString(keyedStateBackend.getCurrentKey().getSerializedKey().array()),
                   window);
             }
             BagState<V> bagState =
@@ -458,7 +458,7 @@ public void clear(ByteString key, W window) {
                   "State clear for {} {} {} {}",
                   pTransformId,
                   userStateId,
-                  Arrays.toString(keyedStateBackend.getCurrentKey().array()),
+                  Arrays.toString(keyedStateBackend.getCurrentKey().getSerializedKey().array()),
                   window);
             }
             BagState<V> bagState =
@@ -469,7 +469,7 @@ public void clear(ByteString key, W window) {
 
         private void prepareStateBackend(ByteString key) {
           // Key for state request is shipped encoded with NESTED context.
-          ByteBuffer encodedKey = FlinkKeyUtils.fromEncodedKey(key);
+          FlinkKey encodedKey = FlinkKey.of(FlinkKeyUtils.fromEncodedKey(key));
           keyedStateBackend.setCurrentKey(encodedKey);
           if (keyStateBackendWithKeyGroupInfo != null) {
             int currentKeyGroupIndex = keyStateBackendWithKeyGroupInfo.getCurrentKeyGroupIndex();
@@ -511,13 +511,13 @@ public void setKeyContextElement1(StreamRecord record) {}
   public void setCurrentKey(Object key) {}
 
   @Override
-  public ByteBuffer getCurrentKey() {
+  public FlinkKey getCurrentKey() {
     // This is the key retrieved by HeapInternalTimerService when setting a Flink timer.
     // Note: Only called by the TimerService. Must be guarded by a lock.
     Preconditions.checkState(
         stateBackendLock.isLocked(),
         "State backend must be locked when retrieving the current key.");
-    return this.<ByteBuffer>getKeyedStateBackend().getCurrentKey();
+    return this.<FlinkKey>getKeyedStateBackend().getCurrentKey();
   }
 
   void setTimer(Timer<?> timerElement, TimerInternals.TimerData timerData) {
@@ -527,8 +527,8 @@ void setTimer(Timer<?> timerElement, TimerInternals.TimerData timerData) {
       LOG.debug("Setting timer: {} {}", timerElement, timerData);
       // KvToByteBufferKeySelector returns the key encoded, it doesn't care about the
       // window, timestamp or pane information.
-      ByteBuffer encodedKey =
-          (ByteBuffer)
+      FlinkKey encodedKey =
+          (FlinkKey)
               keySelector.getKey(
                   WindowedValue.valueInGlobalWindow(
                       (InputT) KV.of(timerElement.getUserKey(), null)));
@@ -562,8 +562,8 @@ class SdfFlinkTimerInternalsFactory implements TimerInternalsFactory<InputT> {
     @Override
     public TimerInternals timerInternalsForKey(InputT key) {
       try {
-        ByteBuffer encodedKey =
-            (ByteBuffer) keySelector.getKey(WindowedValue.valueInGlobalWindow(key));
+        FlinkKey encodedKey =
+            (FlinkKey) keySelector.getKey(WindowedValue.valueInGlobalWindow(key));
         return new SdfFlinkTimerInternals(encodedKey);
       } catch (Exception e) {
         throw new RuntimeException("Couldn't get a timer internals", e);
@@ -576,9 +576,9 @@ public TimerInternals timerInternalsForKey(InputT key) {
    * org.apache.beam.model.fnexecution.v1.BeamFnApi.DelayedBundleApplication}.
    */
   class SdfFlinkTimerInternals implements TimerInternals {
-    private final ByteBuffer key;
+    private final FlinkKey key;
 
-    SdfFlinkTimerInternals(ByteBuffer key) {
+    SdfFlinkTimerInternals(FlinkKey key) {
       this.key = key;
     }
 
@@ -659,8 +659,8 @@ class SdfFlinkStateInternalsFactory implements StateInternalsFactory<InputT> {
     @Override
     public StateInternals stateInternalsForKey(InputT key) {
       try {
-        ByteBuffer encodedKey =
-            (ByteBuffer) keySelector.getKey(WindowedValue.valueInGlobalWindow(key));
+        FlinkKey encodedKey =
+            (FlinkKey) keySelector.getKey(WindowedValue.valueInGlobalWindow(key));
         return new SdfFlinkStateInternals(encodedKey);
       } catch (Exception e) {
         throw new RuntimeException("Couldn't get a state internals", e);
@@ -671,9 +671,9 @@ public StateInternals stateInternalsForKey(InputT key) {
   /** A {@link StateInternals} for keeping {@link DelayedBundleApplication}s as states. */
   class SdfFlinkStateInternals implements StateInternals {
 
-    private final ByteBuffer key;
+    private final FlinkKey key;
 
-    SdfFlinkStateInternals(ByteBuffer key) {
+    SdfFlinkStateInternals(FlinkKey key) {
       this.key = key;
     }
 
@@ -697,7 +697,7 @@ public <T extends State> T state(
   }
 
   @Override
-  protected void fireTimerInternal(ByteBuffer key, TimerInternals.TimerData timer) {
+  protected void fireTimerInternal(FlinkKey key, TimerInternals.TimerData timer) {
     // We have to synchronize to ensure the state backend is not concurrently accessed by the state
     // requests
     try (Locker locker = Locker.locked(stateBackendLock)) {
@@ -774,7 +774,7 @@ DoFnRunner<InputT, OutputT> createBufferingDoFnRunnerIfNeeded(
               serializedOptions,
               keyedBufferingBackend != null ? () -> Locker.locked(stateBackendLock) : null,
               keyedBufferingBackend != null
-                  ? input -> FlinkKeyUtils.encodeKey(((KV) input).getKey(), (Coder) keyCoder)
+                  ? input -> FlinkKey.of(((KV) input).getKey(), (Coder) keyCoder)
                   : null,
               sdkHarnessRunner::emitResults);
     }
@@ -797,7 +797,7 @@ protected DoFnRunner<InputT, OutputT> createWrappingDoFnRunner(
             windowCoder,
             inputCoder,
             this::setTimer,
-            () -> FlinkKeyUtils.decodeKey(getCurrentKey(), keyCoder),
+            () -> FlinkKeyUtils.decodeKey(getCurrentKey().getSerializedKey(), keyCoder),
             keyedStateInternals);
 
     return ensureStateDoFnRunner(sdkHarnessRunner, payload, stepContext);
@@ -1116,7 +1116,7 @@ private DoFnRunner<InputT, OutputT> ensureStateDoFnRunner(
             .map(UserStateReference::localName)
             .collect(Collectors.toList());
 
-    KeyedStateBackend<ByteBuffer> stateBackend = getKeyedStateBackend();
+    KeyedStateBackend<FlinkKey> stateBackend = getKeyedStateBackend();
 
     StateCleaner stateCleaner =
         new StateCleaner(
@@ -1159,7 +1159,7 @@ static class CleanupTimer<InputT> implements StatefulDoFnRunner.CleanupTimer<Inp
     private final WindowingStrategy windowingStrategy;
     private final Coder keyCoder;
     private final Coder windowCoder;
-    private final KeyedStateBackend<ByteBuffer> keyedStateBackend;
+    private final KeyedStateBackend<FlinkKey> keyedStateBackend;
 
     CleanupTimer(
         TimerInternals timerInternals,
@@ -1167,7 +1167,7 @@ static class CleanupTimer<InputT> implements StatefulDoFnRunner.CleanupTimer<Inp
         WindowingStrategy windowingStrategy,
         Coder keyCoder,
         Coder windowCoder,
-        KeyedStateBackend<ByteBuffer> keyedStateBackend) {
+        KeyedStateBackend<FlinkKey> keyedStateBackend) {
       this.timerInternals = timerInternals;
       this.stateBackendLock = stateBackendLock;
       this.windowingStrategy = windowingStrategy;
@@ -1186,7 +1186,7 @@ public void setForWindow(InputT input, BoundedWindow window) {
         return;
       }
       // needs to match the encoding in prepareStateBackend for state request handler
-      final ByteBuffer key = FlinkKeyUtils.encodeKey(((KV) input).getKey(), keyCoder);
+      final FlinkKey key = FlinkKey.of(((KV) input).getKey(), keyCoder);
       // Ensure the state backend is not concurrently accessed by the state requests
       try (Locker locker = Locker.locked(stateBackendLock)) {
         keyedStateBackend.setCurrentKey(key);
@@ -1221,15 +1221,15 @@ static class StateCleaner implements StatefulDoFnRunner.StateCleaner<BoundedWind
 
     private final List<String> userStateNames;
     private final Coder windowCoder;
-    private final ArrayDeque<KV<ByteBuffer, BoundedWindow>> cleanupQueue;
-    private final Supplier<ByteBuffer> currentKeySupplier;
+    private final ArrayDeque<KV<FlinkKey, BoundedWindow>> cleanupQueue;
+    private final Supplier<FlinkKey> currentKeySupplier;
     private final ThrowingFunction<Long, Boolean> hasPendingEventTimeTimers;
     private final CleanupTimer cleanupTimer;
 
     StateCleaner(
         List<String> userStateNames,
         Coder windowCoder,
-        Supplier<ByteBuffer> currentKeySupplier,
+        Supplier<FlinkKey> currentKeySupplier,
         ThrowingFunction<Long, Boolean> hasPendingEventTimeTimers,
         CleanupTimer cleanupTimer) {
       this.userStateNames = userStateNames;
@@ -1247,11 +1247,10 @@ public void clearForWindow(BoundedWindow window) {
       cleanupQueue.add(KV.of(currentKeySupplier.get(), window));
     }
 
-    @SuppressWarnings("ByteBufferBackingArray")
-    void cleanupState(StateInternals stateInternals, Consumer<ByteBuffer> keyContextConsumer)
+    void cleanupState(StateInternals stateInternals, Consumer<FlinkKey> keyContextConsumer)
         throws Exception {
       while (!cleanupQueue.isEmpty()) {
-        KV<ByteBuffer, BoundedWindow> kv = Preconditions.checkNotNull(cleanupQueue.remove());
+        KV<FlinkKey, BoundedWindow> kv = Preconditions.checkNotNull(cleanupQueue.remove());
         BoundedWindow window = Preconditions.checkNotNull(kv.getValue());
         keyContextConsumer.accept(kv.getKey());
         // Check whether we have pending timers which were set during the bundle.
@@ -1260,7 +1259,7 @@ void cleanupState(StateInternals stateInternals, Consumer<ByteBuffer> keyContext
           cleanupTimer.setCleanupTimer(window);
         } else {
           if (LOG.isDebugEnabled()) {
-            LOG.debug("State cleanup for {} {}", Arrays.toString(kv.getKey().array()), window);
+            LOG.debug("State cleanup for {} {}", Arrays.toString(kv.getKey().getSerializedKey().array()), window);
           }
           // No more timers (finally!). Time to clean up.
           for (String userState : userStateNames) {
diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/KvToByteBufferKeySelector.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/KvToFlinkKeyKeySelector.java
similarity index 62%
rename from runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/KvToByteBufferKeySelector.java
rename to runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/KvToFlinkKeyKeySelector.java
index 204247b1d836..a852a724c040 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/KvToByteBufferKeySelector.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/KvToFlinkKeyKeySelector.java
@@ -17,40 +17,37 @@
  */
 package org.apache.beam.runners.flink.translation.wrappers.streaming;
 
-import java.nio.ByteBuffer;
-import org.apache.beam.runners.core.construction.SerializablePipelineOptions;
-import org.apache.beam.runners.flink.translation.types.CoderTypeInformation;
+import org.apache.beam.runners.flink.adapter.FlinkKey;
 import org.apache.beam.sdk.coders.Coder;
 import org.apache.beam.sdk.util.WindowedValue;
 import org.apache.beam.sdk.values.KV;
 import org.apache.flink.api.common.typeinfo.TypeInformation;
 import org.apache.flink.api.java.functions.KeySelector;
 import org.apache.flink.api.java.typeutils.ResultTypeQueryable;
+import org.apache.flink.api.java.typeutils.ValueTypeInfo;
 
 /**
  * {@link KeySelector} that retrieves a key from a {@link KV}. This will return the key as encoded
- * by the provided {@link Coder} in a {@link ByteBuffer}. This ensures that all key
+ * by the provided {@link Coder} in a {@link FlinkKey}. This ensures that all key
  * comparisons/hashing happen on the encoded form.
  */
-public class KvToByteBufferKeySelector<K, V>
-    implements KeySelector<WindowedValue<KV<K, V>>, ByteBuffer>, ResultTypeQueryable<ByteBuffer> {
+public class KvToFlinkKeyKeySelector<K, V>
+    implements KeySelector<WindowedValue<KV<K, V>>, FlinkKey>, ResultTypeQueryable<FlinkKey> {
 
   private final Coder<K> keyCoder;
-  private final SerializablePipelineOptions pipelineOptions;
 
-  public KvToByteBufferKeySelector(Coder<K> keyCoder, SerializablePipelineOptions pipelineOptions) {
+  public KvToFlinkKeyKeySelector(Coder<K> keyCoder) {
     this.keyCoder = keyCoder;
-    this.pipelineOptions = pipelineOptions;
   }
 
   @Override
-  public ByteBuffer getKey(WindowedValue<KV<K, V>> value) {
+  public FlinkKey getKey(WindowedValue<KV<K, V>> value) {
     K key = value.getValue().getKey();
-    return FlinkKeyUtils.encodeKey(key, keyCoder);
+    return FlinkKey.of(key, keyCoder);
   }
 
   @Override
-  public TypeInformation<ByteBuffer> getProducedType() {
-    return new CoderTypeInformation<>(FlinkKeyUtils.ByteBufferCoder.of(), pipelineOptions);
+  public TypeInformation<FlinkKey> getProducedType() {
+    return ValueTypeInfo.of(FlinkKey.class);
   }
 }
diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/SdfByteBufferKeySelector.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/SdfFlinkKeyKeySelector.java
similarity index 75%
rename from runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/SdfByteBufferKeySelector.java
rename to runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/SdfFlinkKeyKeySelector.java
index 8c6f10abf448..176a585e993d 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/SdfByteBufferKeySelector.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/SdfFlinkKeyKeySelector.java
@@ -19,6 +19,7 @@
 
 import java.nio.ByteBuffer;
 import org.apache.beam.runners.core.construction.SerializablePipelineOptions;
+import org.apache.beam.runners.flink.adapter.FlinkKey;
 import org.apache.beam.runners.flink.translation.types.CoderTypeInformation;
 import org.apache.beam.sdk.coders.Coder;
 import org.apache.beam.sdk.util.WindowedValue;
@@ -26,36 +27,35 @@
 import org.apache.flink.api.common.typeinfo.TypeInformation;
 import org.apache.flink.api.java.functions.KeySelector;
 import org.apache.flink.api.java.typeutils.ResultTypeQueryable;
+import org.apache.flink.api.java.typeutils.ValueTypeInfo;
 
 /**
  * {@link KeySelector} that retrieves a key from a {@code KV<KV<element, KV<restriction,
  * watermarkState>>, size>}. This will return the element as encoded by the provided {@link Coder}
- * in a {@link ByteBuffer}. This ensures that all key comparisons/hashing happen on the encoded
+ * in a {@link FlinkKey}. This ensures that all key comparisons/hashing happen on the encoded
  * form. Note that the reason we don't use the whole {@code KV<KV<element, KV<restriction,
  * watermarkState>>, Double>} as the key is when checkpoint happens, we will get different
  * restriction/watermarkState/size, which Flink treats as a new key. Using new key to set state and
  * timer may cause defined behavior.
  */
-public class SdfByteBufferKeySelector<K, V>
-    implements KeySelector<WindowedValue<KV<KV<K, V>, Double>>, ByteBuffer>,
-        ResultTypeQueryable<ByteBuffer> {
+public class SdfFlinkKeyKeySelector<K, V>
+    implements KeySelector<WindowedValue<KV<KV<K, V>, Double>>, FlinkKey>,
+        ResultTypeQueryable<FlinkKey> {
 
   private final Coder<K> keyCoder;
-  private final SerializablePipelineOptions pipelineOptions;
 
-  public SdfByteBufferKeySelector(Coder<K> keyCoder, SerializablePipelineOptions pipelineOptions) {
+  public SdfFlinkKeyKeySelector(Coder<K> keyCoder) {
     this.keyCoder = keyCoder;
-    this.pipelineOptions = pipelineOptions;
   }
 
   @Override
-  public ByteBuffer getKey(WindowedValue<KV<KV<K, V>, Double>> value) {
+  public FlinkKey getKey(WindowedValue<KV<KV<K, V>, Double>> value) {
     K key = value.getValue().getKey().getKey();
-    return FlinkKeyUtils.encodeKey(key, keyCoder);
+    return FlinkKey.of(key, keyCoder);
   }
 
   @Override
-  public TypeInformation<ByteBuffer> getProducedType() {
-    return new CoderTypeInformation<>(FlinkKeyUtils.ByteBufferCoder.of(), pipelineOptions);
+  public TypeInformation<FlinkKey> getProducedType() {
+    return ValueTypeInfo.of(FlinkKey.class);
   }
 }
diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/WorkItemKeySelector.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/WorkItemKeySelector.java
index 64ea6ca26d4d..d809f4287983 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/WorkItemKeySelector.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/WorkItemKeySelector.java
@@ -19,13 +19,13 @@
 
 import java.nio.ByteBuffer;
 import org.apache.beam.runners.core.KeyedWorkItem;
-import org.apache.beam.runners.core.construction.SerializablePipelineOptions;
-import org.apache.beam.runners.flink.translation.types.CoderTypeInformation;
+import org.apache.beam.runners.flink.adapter.FlinkKey;
 import org.apache.beam.sdk.coders.Coder;
 import org.apache.beam.sdk.util.WindowedValue;
 import org.apache.flink.api.common.typeinfo.TypeInformation;
 import org.apache.flink.api.java.functions.KeySelector;
 import org.apache.flink.api.java.typeutils.ResultTypeQueryable;
+import org.apache.flink.api.java.typeutils.ValueTypeInfo;
 
 /**
  * {@link KeySelector} that retrieves a key from a {@link KeyedWorkItem}. This will return the key
@@ -33,25 +33,23 @@
  * comparisons/hashing happen on the encoded form.
  */
 public class WorkItemKeySelector<K, V>
-    implements KeySelector<WindowedValue<KeyedWorkItem<K, V>>, ByteBuffer>,
-        ResultTypeQueryable<ByteBuffer> {
+    implements KeySelector<WindowedValue<KeyedWorkItem<K, V>>, FlinkKey>,
+        ResultTypeQueryable<FlinkKey> {
 
   private final Coder<K> keyCoder;
-  private final SerializablePipelineOptions pipelineOptions;
 
-  public WorkItemKeySelector(Coder<K> keyCoder, SerializablePipelineOptions pipelineOptions) {
+  public WorkItemKeySelector(Coder<K> keyCoder) {
     this.keyCoder = keyCoder;
-    this.pipelineOptions = pipelineOptions;
   }
 
   @Override
-  public ByteBuffer getKey(WindowedValue<KeyedWorkItem<K, V>> value) throws Exception {
+  public FlinkKey getKey(WindowedValue<KeyedWorkItem<K, V>> value) throws Exception {
     K key = value.getValue().key();
-    return FlinkKeyUtils.encodeKey(key, keyCoder);
+    return FlinkKey.of(key, keyCoder);
   }
 
   @Override
-  public TypeInformation<ByteBuffer> getProducedType() {
-    return new CoderTypeInformation<>(FlinkKeyUtils.ByteBufferCoder.of(), pipelineOptions);
+  public TypeInformation<FlinkKey> getProducedType() {
+    return ValueTypeInfo.of(FlinkKey.class);
   }
 }
diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/io/DedupingOperator.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/io/DedupingOperator.java
index d43723964844..9d238aa36110 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/io/DedupingOperator.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/io/DedupingOperator.java
@@ -17,8 +17,8 @@
  */
 package org.apache.beam.runners.flink.translation.wrappers.streaming.io;
 
-import java.nio.ByteBuffer;
 import org.apache.beam.runners.core.construction.SerializablePipelineOptions;
+import org.apache.beam.runners.flink.adapter.FlinkKey;
 import org.apache.beam.sdk.io.FileSystems;
 import org.apache.beam.sdk.options.PipelineOptions;
 import org.apache.beam.sdk.util.WindowedValue;
@@ -43,7 +43,7 @@
 })
 public class DedupingOperator<T> extends AbstractStreamOperator<WindowedValue<T>>
     implements OneInputStreamOperator<WindowedValue<ValueWithRecordId<T>>, WindowedValue<T>>,
-        Triggerable<ByteBuffer, VoidNamespace> {
+        Triggerable<FlinkKey, VoidNamespace> {
 
   private static final long MAX_RETENTION_SINCE_ACCESS = Duration.standardMinutes(10L).getMillis();
   private final SerializablePipelineOptions options;
@@ -94,12 +94,12 @@ public void processElement(StreamRecord<WindowedValue<ValueWithRecordId<T>>> str
   }
 
   @Override
-  public void onEventTime(InternalTimer<ByteBuffer, VoidNamespace> internalTimer) {
+  public void onEventTime(InternalTimer<FlinkKey, VoidNamespace> internalTimer) {
     // will never happen
   }
 
   @Override
-  public void onProcessingTime(InternalTimer<ByteBuffer, VoidNamespace> internalTimer)
+  public void onProcessingTime(InternalTimer<FlinkKey, VoidNamespace> internalTimer)
       throws Exception {
     ValueState<Long> dedupingState = getPartitionedState(dedupingStateDescriptor);
 
diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/state/FlinkStateInternals.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/state/FlinkStateInternals.java
index 2856813ce6ad..47390428d4bd 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/state/FlinkStateInternals.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/state/FlinkStateInternals.java
@@ -18,7 +18,6 @@
 package org.apache.beam.runners.flink.translation.wrappers.streaming.state;
 
 import java.io.IOException;
-import java.nio.ByteBuffer;
 import java.util.Collections;
 import java.util.HashSet;
 import java.util.Iterator;
@@ -35,6 +34,7 @@
 import org.apache.beam.runners.core.StateTag;
 import org.apache.beam.runners.core.construction.SerializablePipelineOptions;
 import org.apache.beam.runners.flink.FlinkPipelineOptions;
+import org.apache.beam.runners.flink.adapter.FlinkKey;
 import org.apache.beam.runners.flink.translation.types.CoderTypeSerializer;
 import org.apache.beam.runners.flink.translation.wrappers.streaming.FlinkKeyUtils;
 import org.apache.beam.sdk.coders.Coder;
@@ -97,7 +97,7 @@
  * {@link StateInternals} that uses a Flink {@link KeyedStateBackend} to manage state.
  *
  * <p>Note: In the Flink streaming runner the key is always encoded using an {@link Coder} and
- * stored in a {@link ByteBuffer}.
+ * stored in a {@link FlinkKey}.
  */
 @SuppressWarnings({
   "rawtypes", // TODO(https://github.com/apache/beam/issues/20447)
@@ -108,7 +108,7 @@ public class FlinkStateInternals<K> implements StateInternals {
   private static final StateNamespace globalWindowNamespace =
       StateNamespaces.window(GlobalWindow.Coder.INSTANCE, GlobalWindow.INSTANCE);
 
-  private final KeyedStateBackend<ByteBuffer> flinkStateBackend;
+  private final KeyedStateBackend<FlinkKey> flinkStateBackend;
   private final Coder<K> keyCoder;
   FlinkStateNamespaceKeySerializer namespaceKeySerializer;
 
@@ -174,7 +174,7 @@ public String toString() {
   private final boolean fasterCopy;
 
   public FlinkStateInternals(
-      KeyedStateBackend<ByteBuffer> flinkStateBackend,
+      KeyedStateBackend<FlinkKey> flinkStateBackend,
       Coder<K> keyCoder,
       Coder<? extends BoundedWindow> windowCoder,
       SerializablePipelineOptions pipelineOptions)
@@ -203,8 +203,8 @@ public Long minWatermarkHoldMs() {
 
   @Override
   public K getKey() {
-    ByteBuffer keyBytes = flinkStateBackend.getCurrentKey();
-    return FlinkKeyUtils.decodeKey(keyBytes, keyCoder);
+    FlinkKey keyBytes = flinkStateBackend.getCurrentKey();
+    return FlinkKeyUtils.decodeKey(keyBytes.getSerializedKey(), keyCoder);
   }
 
   @Override
@@ -517,11 +517,11 @@ private static class FlinkValueState<T> implements ValueState<T> {
     private final StateNamespace namespace;
     private final String stateId;
     private final ValueStateDescriptor<T> flinkStateDescriptor;
-    private final KeyedStateBackend<ByteBuffer> flinkStateBackend;
+    private final KeyedStateBackend<FlinkKey> flinkStateBackend;
     private final FlinkStateNamespaceKeySerializer namespaceSerializer;
 
     FlinkValueState(
-        KeyedStateBackend<ByteBuffer> flinkStateBackend,
+        KeyedStateBackend<FlinkKey> flinkStateBackend,
         String stateId,
         StateNamespace namespace,
         Coder<T> coder,
@@ -600,11 +600,11 @@ public int hashCode() {
   private static class FlinkOrderedListState<T> implements OrderedListState<T> {
     private final StateNamespace namespace;
     private final ListStateDescriptor<TimestampedValue<T>> flinkStateDescriptor;
-    private final KeyedStateBackend<ByteBuffer> flinkStateBackend;
+    private final KeyedStateBackend<FlinkKey> flinkStateBackend;
     private final FlinkStateNamespaceKeySerializer namespaceSerializer;
 
     FlinkOrderedListState(
-        KeyedStateBackend<ByteBuffer> flinkStateBackend,
+        KeyedStateBackend<FlinkKey> flinkStateBackend,
         String stateId,
         StateNamespace namespace,
         Coder<T> coder,
@@ -723,12 +723,12 @@ private static class FlinkBagState<T> implements BagState<T> {
     private final StateNamespace namespace;
     private final String stateId;
     private final ListStateDescriptor<T> flinkStateDescriptor;
-    private final KeyedStateBackend<ByteBuffer> flinkStateBackend;
+    private final KeyedStateBackend<FlinkKey> flinkStateBackend;
     private final boolean storesVoidValues;
     private final FlinkStateNamespaceKeySerializer namespaceSerializer;
 
     FlinkBagState(
-        KeyedStateBackend<ByteBuffer> flinkStateBackend,
+        KeyedStateBackend<FlinkKey> flinkStateBackend,
         String stateId,
         StateNamespace namespace,
         Coder<T> coder,
@@ -864,11 +864,11 @@ private static class FlinkCombiningState<K, InputT, AccumT, OutputT>
     private final String stateId;
     private final Combine.CombineFn<InputT, AccumT, OutputT> combineFn;
     private final ValueStateDescriptor<AccumT> flinkStateDescriptor;
-    private final KeyedStateBackend<ByteBuffer> flinkStateBackend;
+    private final KeyedStateBackend<FlinkKey> flinkStateBackend;
     private final FlinkStateNamespaceKeySerializer namespaceSerializer;
 
     FlinkCombiningState(
-        KeyedStateBackend<ByteBuffer> flinkStateBackend,
+        KeyedStateBackend<FlinkKey> flinkStateBackend,
         String stateId,
         Combine.CombineFn<InputT, AccumT, OutputT> combineFn,
         StateNamespace namespace,
@@ -1026,12 +1026,12 @@ private static class FlinkCombiningStateWithContext<K, InputT, AccumT, OutputT>
     private final String stateId;
     private final CombineWithContext.CombineFnWithContext<InputT, AccumT, OutputT> combineFn;
     private final ValueStateDescriptor<AccumT> flinkStateDescriptor;
-    private final KeyedStateBackend<ByteBuffer> flinkStateBackend;
+    private final KeyedStateBackend<FlinkKey> flinkStateBackend;
     private final CombineWithContext.Context context;
     private final FlinkStateNamespaceKeySerializer namespaceSerializer;
 
     FlinkCombiningStateWithContext(
-        KeyedStateBackend<ByteBuffer> flinkStateBackend,
+        KeyedStateBackend<FlinkKey> flinkStateBackend,
         String stateId,
         CombineWithContext.CombineFnWithContext<InputT, AccumT, OutputT> combineFn,
         StateNamespace namespace,
@@ -1192,7 +1192,7 @@ private class FlinkWatermarkHoldState implements WatermarkHoldState {
     private org.apache.flink.api.common.state.MapState<String, Instant> watermarkHoldsState;
 
     public FlinkWatermarkHoldState(
-        KeyedStateBackend<ByteBuffer> flinkStateBackend,
+        KeyedStateBackend<FlinkKey> flinkStateBackend,
         MapStateDescriptor<String, Instant> watermarkHoldStateDescriptor,
         String stateId,
         StateNamespace namespace,
@@ -1314,11 +1314,11 @@ private static class FlinkMapState<KeyT, ValueT> implements MapState<KeyT, Value
     private final StateNamespace namespace;
     private final String stateId;
     private final MapStateDescriptor<KeyT, ValueT> flinkStateDescriptor;
-    private final KeyedStateBackend<ByteBuffer> flinkStateBackend;
+    private final KeyedStateBackend<FlinkKey> flinkStateBackend;
     private final FlinkStateNamespaceKeySerializer namespaceSerializer;
 
     FlinkMapState(
-        KeyedStateBackend<ByteBuffer> flinkStateBackend,
+        KeyedStateBackend<FlinkKey> flinkStateBackend,
         String stateId,
         StateNamespace namespace,
         Coder<KeyT> mapKeyCoder,
@@ -1533,11 +1533,11 @@ private static class FlinkSetState<T> implements SetState<T> {
     private final StateNamespace namespace;
     private final String stateId;
     private final MapStateDescriptor<T, Boolean> flinkStateDescriptor;
-    private final KeyedStateBackend<ByteBuffer> flinkStateBackend;
+    private final KeyedStateBackend<FlinkKey> flinkStateBackend;
     private final FlinkStateNamespaceKeySerializer namespaceSerializer;
 
     FlinkSetState(
-        KeyedStateBackend<ByteBuffer> flinkStateBackend,
+        KeyedStateBackend<FlinkKey> flinkStateBackend,
         String stateId,
         StateNamespace namespace,
         Coder<T> coder,
@@ -1690,9 +1690,9 @@ private void restoreWatermarkHoldsView() throws Exception {
     org.apache.flink.api.common.state.MapState<String, Instant> mapState =
         flinkStateBackend.getPartitionedState(
             VoidNamespace.INSTANCE, VoidNamespaceSerializer.INSTANCE, watermarkHoldStateDescriptor);
-    try (Stream<ByteBuffer> keys =
+    try (Stream<FlinkKey> keys =
         flinkStateBackend.getKeys(watermarkHoldStateDescriptor.getName(), VoidNamespace.INSTANCE)) {
-      Iterator<ByteBuffer> iterator = keys.iterator();
+      Iterator<FlinkKey> iterator = keys.iterator();
       while (iterator.hasNext()) {
         flinkStateBackend.setCurrentKey(iterator.next());
         mapState.values().forEach(this::addWatermarkHoldUsage);
diff --git a/runners/flink/src/test/java/org/apache/beam/runners/flink/adapter/FlinkKeyTest.java b/runners/flink/src/test/java/org/apache/beam/runners/flink/adapter/FlinkKeyTest.java
new file mode 100644
index 000000000000..97f9228c8499
--- /dev/null
+++ b/runners/flink/src/test/java/org/apache/beam/runners/flink/adapter/FlinkKeyTest.java
@@ -0,0 +1,80 @@
+package org.apache.beam.runners.flink.adapter;
+
+import com.google.common.collect.Range;
+import org.apache.beam.sdk.coders.VarIntCoder;
+import org.apache.flink.api.common.typeinfo.TypeInformation;
+import org.apache.flink.api.common.typeutils.TypeSerializer;
+import org.apache.flink.api.java.tuple.Tuple2;
+import org.apache.flink.api.java.typeutils.GenericTypeInfo;
+import org.apache.flink.api.java.typeutils.TypeExtractor;
+import org.apache.flink.api.java.typeutils.ValueTypeInfo;
+import org.apache.flink.util.MathUtils;
+import org.hamcrest.Matchers;
+import org.hamcrest.core.IsEqual;
+import org.hamcrest.core.IsInstanceOf;
+import org.junit.Test;
+import java.nio.ByteBuffer;
+import java.nio.charset.StandardCharsets;
+import java.util.Set;
+import java.util.stream.Collectors;
+import java.util.stream.IntStream;
+import java.util.stream.Stream;
+
+import static org.hamcrest.MatcherAssert.*;
+import static org.hamcrest.Matchers.equalTo;
+import static org.hamcrest.Matchers.greaterThan;
+import static org.hamcrest.Matchers.not;
+
+public class FlinkKeyTest {
+  @Test
+  public void testIsRecognizedAsValue() {
+    byte[] bs = "foobar".getBytes(StandardCharsets.UTF_8);
+    ByteBuffer buf = ByteBuffer.wrap(bs);
+    FlinkKey key = FlinkKey.of(buf);
+    TypeInformation<FlinkKey> tpe = TypeExtractor.getForObject(key);
+
+    assertThat(tpe, IsInstanceOf.instanceOf(ValueTypeInfo.class));
+
+    TypeInformation<Tuple2<FlinkKey, byte[]>> tupleTpe = TypeExtractor.getForObject(Tuple2.of(key, bs));
+    assertThat(tupleTpe, not(IsInstanceOf.instanceOf(GenericTypeInfo.class)));
+  }
+
+  @Test
+  public void testIsConsistent() {
+    byte[] bs = "foobar".getBytes(StandardCharsets.UTF_8);
+    byte[] bs2 = "foobar".getBytes(StandardCharsets.UTF_8);
+
+    FlinkKey key1 = FlinkKey.of(ByteBuffer.wrap(bs));
+    FlinkKey key2 = FlinkKey.of(ByteBuffer.wrap(bs2));
+
+    assertThat(key1, equalTo(key2));
+    assertThat(key1.hashCode(), equalTo(key2.hashCode()));
+  }
+
+  private void checkDistribution(int numKeys) {
+    int paralellism = 2100;
+
+    Set<Integer> hashcodes = IntStream.range(0, numKeys)
+        .mapToObj(i -> FlinkKey.of(i, VarIntCoder.of()))
+        .map(k -> k.hashCode())
+        .collect(Collectors.toSet());
+
+    Set<Integer> keyGroups =
+        hashcodes.stream()
+            .map(hash -> MathUtils.murmurHash(hash) % paralellism)
+            .collect(Collectors.toSet());
+
+    assertThat((double) hashcodes.size(), greaterThan(numKeys * 0.95));
+    assertThat((double) keyGroups.size(), greaterThan(paralellism * 0.95));
+  }
+
+  @Test
+  public void testWillBeWellDistributedForSmallKeyGroups() {
+    checkDistribution(8192);
+  }
+
+  @Test
+  public void testWillBeWellDistributedForLargeKeyGroups() {
+    checkDistribution(1000000);
+  }
+}
diff --git a/runners/flink/src/test/java/org/apache/beam/runners/flink/streaming/FlinkStateInternalsTest.java b/runners/flink/src/test/java/org/apache/beam/runners/flink/streaming/FlinkStateInternalsTest.java
index b816e79991ab..95c255159e6f 100644
--- a/runners/flink/src/test/java/org/apache/beam/runners/flink/streaming/FlinkStateInternalsTest.java
+++ b/runners/flink/src/test/java/org/apache/beam/runners/flink/streaming/FlinkStateInternalsTest.java
@@ -30,6 +30,7 @@
 import org.apache.beam.runners.core.StateTags;
 import org.apache.beam.runners.core.construction.SerializablePipelineOptions;
 import org.apache.beam.runners.flink.FlinkPipelineOptions;
+import org.apache.beam.runners.flink.adapter.FlinkKey;
 import org.apache.beam.runners.flink.translation.wrappers.streaming.state.FlinkStateInternals;
 import org.apache.beam.sdk.coders.CoderException;
 import org.apache.beam.sdk.coders.StringUtf8Coder;
@@ -40,6 +41,7 @@
 import org.apache.flink.api.common.ExecutionConfig;
 import org.apache.flink.api.common.JobID;
 import org.apache.flink.api.java.typeutils.GenericTypeInfo;
+import org.apache.flink.api.java.typeutils.ValueTypeInfo;
 import org.apache.flink.core.fs.CloseableRegistry;
 import org.apache.flink.runtime.jobgraph.JobVertexID;
 import org.apache.flink.runtime.operators.testutils.DummyEnvironment;
@@ -64,7 +66,7 @@ public class FlinkStateInternalsTest extends StateInternalsTest {
   @Override
   protected StateInternals createStateInternals() {
     try {
-      KeyedStateBackend<ByteBuffer> keyedStateBackend = createStateBackend();
+      KeyedStateBackend<FlinkKey> keyedStateBackend = createStateBackend();
       return new FlinkStateInternals<>(
           keyedStateBackend,
           StringUtf8Coder.of(),
@@ -77,7 +79,7 @@ protected StateInternals createStateInternals() {
 
   @Test
   public void testWatermarkHoldsPersistence() throws Exception {
-    KeyedStateBackend<ByteBuffer> keyedStateBackend = createStateBackend();
+    KeyedStateBackend<FlinkKey> keyedStateBackend = createStateBackend();
     FlinkStateInternals stateInternals =
         new FlinkStateInternals<>(
             keyedStateBackend,
@@ -116,9 +118,9 @@ public void testWatermarkHoldsPersistence() throws Exception {
     assertThat(stateInternals.minWatermarkHoldMs(), is(low.getMillis()));
 
     // Watermark hold should be computed across all keys
-    ByteBuffer firstKey = keyedStateBackend.getCurrentKey();
+    FlinkKey firstKey = keyedStateBackend.getCurrentKey();
     changeKey(keyedStateBackend);
-    ByteBuffer secondKey = keyedStateBackend.getCurrentKey();
+    FlinkKey secondKey = keyedStateBackend.getCurrentKey();
     assertThat(firstKey, is(Matchers.not(secondKey)));
     assertThat(stateInternals.minWatermarkHoldMs(), is(low.getMillis()));
     // ..but be tracked per key / window
@@ -171,7 +173,7 @@ public void testWatermarkHoldsPersistence() throws Exception {
 
   @Test
   public void testGlobalWindowWatermarkHoldClear() throws Exception {
-    KeyedStateBackend<ByteBuffer> keyedStateBackend = createStateBackend();
+    KeyedStateBackend<FlinkKey> keyedStateBackend = createStateBackend();
     FlinkStateInternals<String> stateInternals =
         new FlinkStateInternals<>(
             keyedStateBackend,
@@ -187,13 +189,13 @@ public void testGlobalWindowWatermarkHoldClear() throws Exception {
     assertThat(state.read(), is((Instant) null));
   }
 
-  public static KeyedStateBackend<ByteBuffer> createStateBackend() throws Exception {
-    AbstractKeyedStateBackend<ByteBuffer> keyedStateBackend =
+  public static KeyedStateBackend<FlinkKey> createStateBackend() throws Exception {
+    AbstractKeyedStateBackend<FlinkKey> keyedStateBackend =
         MemoryStateBackendWrapper.createKeyedStateBackend(
             new DummyEnvironment("test", 1, 0),
             new JobID(),
             "test_op",
-            new GenericTypeInfo<>(ByteBuffer.class).createSerializer(new ExecutionConfig()),
+            new ValueTypeInfo<>(FlinkKey.class).createSerializer(new ExecutionConfig()),
             2,
             new KeyGroupRange(0, 1),
             new KvStateRegistry().createTaskRegistry(new JobID(), new JobVertexID()),
@@ -207,10 +209,10 @@ public static KeyedStateBackend<ByteBuffer> createStateBackend() throws Exceptio
     return keyedStateBackend;
   }
 
-  private static void changeKey(KeyedStateBackend<ByteBuffer> keyedStateBackend)
+  private static void changeKey(KeyedStateBackend<FlinkKey> keyedStateBackend)
       throws CoderException {
     keyedStateBackend.setCurrentKey(
-        ByteBuffer.wrap(
-            CoderUtils.encodeToByteArray(StringUtf8Coder.of(), UUID.randomUUID().toString())));
+        FlinkKey.of(ByteBuffer.wrap(
+            CoderUtils.encodeToByteArray(StringUtf8Coder.of(), UUID.randomUUID().toString()))));
   }
 }
diff --git a/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/DoFnOperatorTest.java b/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/DoFnOperatorTest.java
index 67e21a17bc6b..7db97769d97a 100644
--- a/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/DoFnOperatorTest.java
+++ b/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/DoFnOperatorTest.java
@@ -32,7 +32,6 @@
 
 import com.fasterxml.jackson.databind.type.TypeFactory;
 import com.fasterxml.jackson.databind.util.LRUMap;
-import java.nio.ByteBuffer;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
@@ -52,8 +51,8 @@
 import org.apache.beam.runners.core.TimerInternals;
 import org.apache.beam.runners.core.construction.SerializablePipelineOptions;
 import org.apache.beam.runners.flink.FlinkPipelineOptions;
+import org.apache.beam.runners.flink.adapter.FlinkKey;
 import org.apache.beam.runners.flink.metrics.FlinkMetricContainer;
-import org.apache.beam.runners.flink.translation.types.CoderTypeInformation;
 import org.apache.beam.runners.flink.translation.types.CoderTypeSerializer;
 import org.apache.beam.sdk.Pipeline;
 import org.apache.beam.sdk.coders.Coder;
@@ -96,6 +95,7 @@
 import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.Iterables;
 import org.apache.flink.api.common.typeinfo.TypeInformation;
 import org.apache.flink.api.java.functions.KeySelector;
+import org.apache.flink.api.java.typeutils.ValueTypeInfo;
 import org.apache.flink.runtime.checkpoint.OperatorSubtaskState;
 import org.apache.flink.streaming.runtime.streamrecord.StreamRecord;
 import org.apache.flink.streaming.util.KeyedOneInputStreamOperatorTestHarness;
@@ -348,8 +348,8 @@ public void onProcessingTime(OnTimerContext context) {
         WindowedValue.getFullCoder(
             StringUtf8Coder.of(), windowingStrategy.getWindowFn().windowCoder());
 
-    KeySelector<WindowedValue<Integer>, ByteBuffer> keySelector =
-        e -> FlinkKeyUtils.encodeKey(e.getValue(), keyCoder);
+    KeySelector<WindowedValue<Integer>, FlinkKey> keySelector =
+        e -> FlinkKey.of(e.getValue(), keyCoder);
 
     TupleTag<String> outputTag = new TupleTag<>("main-output");
 
@@ -378,8 +378,7 @@ public void onProcessingTime(OnTimerContext context) {
         new KeyedOneInputStreamOperatorTestHarness<>(
             doFnOperator,
             keySelector,
-            new CoderTypeInformation<>(
-                FlinkKeyUtils.ByteBufferCoder.of(), FlinkPipelineOptions.defaults()));
+            ValueTypeInfo.of(FlinkKey.class));
 
     testHarness.setup(
         new CoderTypeSerializer<>(
@@ -438,8 +437,9 @@ public void testWatermarkUpdateAfterWatermarkHoldRelease() throws Exception {
 
     TupleTag<KV<String, String>> outputTag = new TupleTag<>("main-output");
     List<Long> emittedWatermarkHolds = new ArrayList<>();
-    KeySelector<WindowedValue<KV<String, String>>, ByteBuffer> keySelector =
-        e -> FlinkKeyUtils.encodeKey(e.getValue().getKey(), StringUtf8Coder.of());
+
+    KeySelector<WindowedValue<KV<String, String>>, FlinkKey> keySelector =
+        e -> FlinkKey.of(e.getValue().getKey(), StringUtf8Coder.of());
 
     DoFnOperator<KV<String, String>, KV<String, String>, KV<String, String>> doFnOperator =
         new DoFnOperator<KV<String, String>, KV<String, String>, KV<String, String>>(
@@ -546,8 +546,7 @@ void emitWatermarkIfHoldChanged(long currentWatermarkHold) {
             new KeyedOneInputStreamOperatorTestHarness<>(
                 doFnOperator,
                 keySelector,
-                new CoderTypeInformation<>(
-                    FlinkKeyUtils.ByteBufferCoder.of(), FlinkPipelineOptions.defaults()));
+                ValueTypeInfo.of(FlinkKey.class));
 
     testHarness.setup();
 
@@ -611,8 +610,8 @@ public void processElement(ProcessContext context) {
         WindowedValue.getFullCoder(
             StringUtf8Coder.of(), windowingStrategy.getWindowFn().windowCoder());
 
-    KeySelector<WindowedValue<Integer>, ByteBuffer> keySelector =
-        e -> FlinkKeyUtils.encodeKey(e.getValue(), keyCoder);
+    KeySelector<WindowedValue<Integer>, FlinkKey> keySelector =
+        e -> FlinkKey.of(e.getValue(), keyCoder);
 
     TupleTag<String> outputTag = new TupleTag<>("main-output");
 
@@ -641,8 +640,7 @@ public void processElement(ProcessContext context) {
         new KeyedOneInputStreamOperatorTestHarness<>(
             doFnOperator,
             keySelector,
-            new CoderTypeInformation<>(
-                FlinkKeyUtils.ByteBufferCoder.of(), FlinkPipelineOptions.defaults()));
+            ValueTypeInfo.of(FlinkKey.class));
 
     testHarness.open();
 
@@ -693,7 +691,7 @@ public void testStateGCForStatefulFn() throws Exception {
     final int timerOutput = 4093;
 
     KeyedOneInputStreamOperatorTestHarness<
-            ByteBuffer, WindowedValue<KV<String, Integer>>, WindowedValue<KV<String, Integer>>>
+            FlinkKey, WindowedValue<KV<String, Integer>>, WindowedValue<KV<String, Integer>>>
         testHarness =
             getHarness(
                 windowingStrategy,
@@ -758,7 +756,7 @@ public void testGCForGlobalWindow() throws Exception {
     WindowingStrategy<Object, GlobalWindow> windowingStrategy = WindowingStrategy.globalDefault();
 
     KeyedOneInputStreamOperatorTestHarness<
-            ByteBuffer, WindowedValue<KV<String, Integer>>, WindowedValue<KV<String, Integer>>>
+            FlinkKey, WindowedValue<KV<String, Integer>>, WindowedValue<KV<String, Integer>>>
         testHarness = getHarness(windowingStrategy, 5000, (window) -> new Instant(50), 4092);
 
     testHarness.open();
@@ -818,7 +816,7 @@ public void testGCForGlobalWindow() throws Exception {
   }
 
   private static KeyedOneInputStreamOperatorTestHarness<
-          ByteBuffer, WindowedValue<KV<String, Integer>>, WindowedValue<KV<String, Integer>>>
+          FlinkKey, WindowedValue<KV<String, Integer>>, WindowedValue<KV<String, Integer>>>
       getHarness(
           WindowingStrategy<?, ?> windowingStrategy,
           int elementOffset,
@@ -863,8 +861,8 @@ public void onTimer(OnTimerContext context, @StateId(stateId) ValueState<String>
 
     TupleTag<KV<String, Integer>> outputTag = new TupleTag<>("main-output");
 
-    KeySelector<WindowedValue<KV<String, Integer>>, ByteBuffer> keySelector =
-        e -> FlinkKeyUtils.encodeKey(e.getValue().getKey(), StringUtf8Coder.of());
+    KeySelector<WindowedValue<KV<String, Integer>>, FlinkKey> keySelector =
+        e -> FlinkKey.of(e.getValue().getKey(), StringUtf8Coder.of());
 
     FlinkPipelineOptions options = FlinkPipelineOptions.defaults();
     options.setStreaming(true);
@@ -891,7 +889,7 @@ outputTag, coder, new SerializablePipelineOptions(options)),
     return new KeyedOneInputStreamOperatorTestHarness<>(
         doFnOperator,
         keySelector,
-        new CoderTypeInformation<>(FlinkKeyUtils.ByteBufferCoder.of(), options));
+        ValueTypeInfo.of(FlinkKey.class));
   }
 
   @Test
@@ -914,9 +912,9 @@ void testSideInputs(boolean keyed) throws Exception {
         ImmutableMap.<Integer, PCollectionView<?>>builder().put(1, view1).put(2, view2).build();
 
     Coder<String> keyCoder = StringUtf8Coder.of();
-    KeySelector<WindowedValue<String>, ByteBuffer> keySelector = null;
+    KeySelector<WindowedValue<String>, FlinkKey> keySelector = null;
     if (keyed) {
-      keySelector = value -> FlinkKeyUtils.encodeKey(value.getValue(), keyCoder);
+      keySelector = value -> FlinkKey.of(value.getValue(), keyCoder);
     }
 
     DoFnOperator<String, String, String> doFnOperator =
@@ -948,8 +946,7 @@ outputTag, coder, new SerializablePipelineOptions(FlinkPipelineOptions.defaults(
               doFnOperator,
               keySelector,
               null,
-              new CoderTypeInformation<>(
-                  FlinkKeyUtils.ByteBufferCoder.of(), FlinkPipelineOptions.defaults()));
+              ValueTypeInfo.of(FlinkKey.class));
     }
 
     testHarness.open();
@@ -1038,16 +1035,16 @@ public void processElement(
     TupleTag<KV<String, Long>> outputTag = new TupleTag<>("main-output");
 
     StringUtf8Coder keyCoder = StringUtf8Coder.of();
-    KvToByteBufferKeySelector<String, Long> keySelector =
-        new KvToByteBufferKeySelector<>(keyCoder, null);
+    KvToFlinkKeyKeySelector<String, Long> keySelector =
+        new KvToFlinkKeyKeySelector<>(keyCoder);
+
     KvCoder<String, Long> coder = KvCoder.of(keyCoder, VarLongCoder.of());
 
     FullWindowedValueCoder<KV<String, Long>> kvCoder =
         WindowedValue.getFullCoder(coder, windowingStrategy.getWindowFn().windowCoder());
 
-    CoderTypeInformation<ByteBuffer> keyCoderInfo =
-        new CoderTypeInformation<>(
-            FlinkKeyUtils.ByteBufferCoder.of(), FlinkPipelineOptions.defaults());
+    TypeInformation<FlinkKey> keyCoderInfo =
+        ValueTypeInfo.of(FlinkKey.class);
 
     OneInputStreamOperatorTestHarness<
             WindowedValue<KV<String, Long>>, WindowedValue<KV<String, Long>>>
@@ -1151,8 +1148,8 @@ public void keyedParDoSideInputCheckpointing() throws Exception {
               WindowedValue.getFullCoder(keyCoder, IntervalWindow.getCoder());
           TupleTag<String> outputTag = new TupleTag<>("main-output");
 
-          KeySelector<WindowedValue<String>, ByteBuffer> keySelector =
-              e -> FlinkKeyUtils.encodeKey(e.getValue(), keyCoder);
+          KeySelector<WindowedValue<String>, FlinkKey> keySelector =
+              e -> FlinkKey.of(e.getValue(), keyCoder);
 
           ImmutableMap<Integer, PCollectionView<?>> sideInputMapping =
               ImmutableMap.<Integer, PCollectionView<?>>builder()
@@ -1186,8 +1183,7 @@ public void keyedParDoSideInputCheckpointing() throws Exception {
               keySelector,
               // we use a dummy key for the second input since it is considered to be broadcast
               null,
-              new CoderTypeInformation<>(
-                  FlinkKeyUtils.ByteBufferCoder.of(), FlinkPipelineOptions.defaults()));
+              ValueTypeInfo.of(FlinkKey.class));
         });
   }
 
@@ -1298,8 +1294,8 @@ public void keyedParDoPushbackDataCheckpointing() throws Exception {
 
           TupleTag<String> outputTag = new TupleTag<>("main-output");
 
-          KeySelector<WindowedValue<String>, ByteBuffer> keySelector =
-              e -> FlinkKeyUtils.encodeKey(e.getValue(), keyCoder);
+          KeySelector<WindowedValue<String>, FlinkKey> keySelector =
+              e -> FlinkKey.of(e.getValue(), keyCoder);
 
           ImmutableMap<Integer, PCollectionView<?>> sideInputMapping =
               ImmutableMap.<Integer, PCollectionView<?>>builder()
@@ -1333,8 +1329,7 @@ public void keyedParDoPushbackDataCheckpointing() throws Exception {
               keySelector,
               // we use a dummy key for the second input since it is considered to be broadcast
               null,
-              new CoderTypeInformation<>(
-                  FlinkKeyUtils.ByteBufferCoder.of(), FlinkPipelineOptions.defaults()));
+              ValueTypeInfo.of(FlinkKey.class));
         });
   }
 
@@ -1436,11 +1431,10 @@ public void onEventTime(OnTimerContext context) {
     final CoderTypeSerializer<WindowedValue<String>> outputSerializer =
         new CoderTypeSerializer<>(
             outputCoder, new SerializablePipelineOptions(FlinkPipelineOptions.defaults()));
-    CoderTypeInformation<ByteBuffer> keyCoderInfo =
-        new CoderTypeInformation<>(
-            FlinkKeyUtils.ByteBufferCoder.of(), FlinkPipelineOptions.defaults());
-    KeySelector<WindowedValue<Integer>, ByteBuffer> keySelector =
-        e -> FlinkKeyUtils.encodeKey(e.getValue(), keyCoder);
+    TypeInformation<FlinkKey> keyCoderInfo = ValueTypeInfo.of(FlinkKey.class);
+
+    KeySelector<WindowedValue<Integer>, FlinkKey> keySelector =
+        e -> FlinkKey.of(e.getValue(), keyCoder);
 
     OneInputStreamOperatorTestHarness<WindowedValue<Integer>, WindowedValue<String>> testHarness =
         createTestHarness(
@@ -1672,9 +1666,8 @@ public void finishBundle(FinishBundleContext context) {
   public void testBundleKeyed() throws Exception {
 
     StringUtf8Coder keyCoder = StringUtf8Coder.of();
-    KvToByteBufferKeySelector<String, String> keySelector =
-        new KvToByteBufferKeySelector<>(
-            keyCoder, new SerializablePipelineOptions(FlinkPipelineOptions.defaults()));
+    KvToFlinkKeyKeySelector<String, String> keySelector =
+        new KvToFlinkKeyKeySelector<>(keyCoder);
     KvCoder<String, String> kvCoder = KvCoder.of(keyCoder, StringUtf8Coder.of());
     WindowedValue.ValueOnlyWindowedValueCoder<KV<String, String>> windowedValueCoder =
         WindowedValue.getValueOnlyCoder(kvCoder);
@@ -2121,8 +2114,8 @@ public void testExactlyOnceBufferingKeyed() throws Exception {
     TupleTag<KV<String, String>> outputTag = new TupleTag<>("main-output");
 
     StringUtf8Coder keyCoder = StringUtf8Coder.of();
-    KvToByteBufferKeySelector<String, String> keySelector =
-        new KvToByteBufferKeySelector<>(keyCoder, new SerializablePipelineOptions(options));
+    KvToFlinkKeyKeySelector<String, String> keySelector =
+        new KvToFlinkKeyKeySelector<>(keyCoder);
     KvCoder<String, String> kvCoder = KvCoder.of(keyCoder, StringUtf8Coder.of());
     WindowedValue.ValueOnlyWindowedValueCoder<KV<String, String>> windowedValueCoder =
         WindowedValue.getValueOnlyCoder(kvCoder);
@@ -2206,7 +2199,7 @@ public void finishBundle(FinishBundleContext context) {
     assertThat(numStartBundleCalled, is(1));
     assertThat(
         stripStreamRecordFromWindowedValue(testHarness.getOutput()),
-        contains(
+        containsInAnyOrder(
             WindowedValue.valueInGlobalWindow(KV.of("key", "a")),
             WindowedValue.valueInGlobalWindow(KV.of("key", "b")),
             WindowedValue.valueInGlobalWindow(KV.of("key2", "c")),
@@ -2227,7 +2220,7 @@ public void finishBundle(FinishBundleContext context) {
     assertThat(numStartBundleCalled, is(2));
     assertThat(
         stripStreamRecordFromWindowedValue(testHarness.getOutput()),
-        contains(
+        containsInAnyOrder(
             WindowedValue.valueInGlobalWindow(KV.of("key", "a")),
             WindowedValue.valueInGlobalWindow(KV.of("key", "b")),
             WindowedValue.valueInGlobalWindow(KV.of("key2", "c")),
@@ -2240,7 +2233,7 @@ public void finishBundle(FinishBundleContext context) {
     assertThat(numStartBundleCalled, is(2));
     assertThat(
         stripStreamRecordFromWindowedValue(testHarness.getOutput()),
-        contains(
+        containsInAnyOrder(
             WindowedValue.valueInGlobalWindow(KV.of("key", "a")),
             WindowedValue.valueInGlobalWindow(KV.of("key", "b")),
             WindowedValue.valueInGlobalWindow(KV.of("key2", "c")),
@@ -2253,8 +2246,8 @@ public void testFailOnRequiresStableInputAndDisabledCheckpointing() {
     TupleTag<KV<String, String>> outputTag = new TupleTag<>("main-output");
 
     StringUtf8Coder keyCoder = StringUtf8Coder.of();
-    KvToByteBufferKeySelector<String, String> keySelector =
-        new KvToByteBufferKeySelector<>(keyCoder, null);
+    KvToFlinkKeyKeySelector<String, String> keySelector =
+        new KvToFlinkKeyKeySelector<>(keyCoder);
     KvCoder<String, String> kvCoder = KvCoder.of(keyCoder, StringUtf8Coder.of());
     WindowedValue.ValueOnlyWindowedValueCoder<KV<String, String>> windowedValueCoder =
         WindowedValue.getValueOnlyCoder(kvCoder);
diff --git a/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/ExecutableStageDoFnOperatorTest.java b/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/ExecutableStageDoFnOperatorTest.java
index 2eb0545b7794..68cffda38e36 100644
--- a/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/ExecutableStageDoFnOperatorTest.java
+++ b/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/ExecutableStageDoFnOperatorTest.java
@@ -63,6 +63,7 @@
 import org.apache.beam.runners.core.TimerInternals;
 import org.apache.beam.runners.core.construction.SerializablePipelineOptions;
 import org.apache.beam.runners.flink.FlinkPipelineOptions;
+import org.apache.beam.runners.flink.adapter.FlinkKey;
 import org.apache.beam.runners.flink.metrics.DoFnRunnerWithMetricsUpdate;
 import org.apache.beam.runners.flink.streaming.FlinkStateInternalsTest;
 import org.apache.beam.runners.flink.translation.functions.FlinkExecutableStageContextFactory;
@@ -109,6 +110,7 @@
 import org.apache.flink.api.common.cache.DistributedCache;
 import org.apache.flink.api.common.functions.RuntimeContext;
 import org.apache.flink.api.common.typeinfo.TypeInformation;
+import org.apache.flink.api.java.typeutils.ValueTypeInfo;
 import org.apache.flink.runtime.state.KeyedStateBackend;
 import org.apache.flink.streaming.api.watermark.Watermark;
 import org.apache.flink.streaming.runtime.streamrecord.StreamRecord;
@@ -683,7 +685,7 @@ public void testEnsureStateCleanupWithKeyedInputCleanupTimer() {
     cleanupTimer.setForWindow(KV.of("key", "string"), window);
 
     Mockito.verify(stateBackendLock).lock();
-    ByteBuffer key = FlinkKeyUtils.encodeKey("key", keyCoder);
+    FlinkKey key = FlinkKey.of("key", keyCoder);
     Mockito.verify(keyedStateBackend).setCurrentKey(key);
     assertThat(
         inMemoryTimerInternals.getNextTimer(TimeDomain.EVENT_TIME),
@@ -707,9 +709,9 @@ public void testEnsureStateCleanupWithKeyedInputStateCleaner() throws Exception
     }
     ImmutableList<BagState<String>> bagStates = bagStateBuilder.build();
 
-    MutableObject<ByteBuffer> key =
+    MutableObject<FlinkKey> key =
         new MutableObject<>(
-            ByteBuffer.wrap(stateInternals.getKey().getBytes(StandardCharsets.UTF_8)));
+            FlinkKey.of(ByteBuffer.wrap(stateInternals.getKey().getBytes(StandardCharsets.UTF_8))));
 
     // Test that state is cleaned up correctly
     ExecutableStageDoFnOperator.StateCleaner stateCleaner =
@@ -786,21 +788,20 @@ private void testEnsureDeferredStateCleanupTimerFiring(boolean withCheckpointing
     when(bundle.getTimerReceivers()).thenReturn(ImmutableMap.of(timerInputKey, timerReceiver));
 
     KeyedOneInputStreamOperatorTestHarness<
-            ByteBuffer, WindowedValue<KV<String, Integer>>, WindowedValue<Integer>>
+            FlinkKey, WindowedValue<KV<String, Integer>>, WindowedValue<Integer>>
         testHarness =
             new KeyedOneInputStreamOperatorTestHarness(
                 operator,
                 operator.keySelector,
-                new CoderTypeInformation<>(
-                    FlinkKeyUtils.ByteBufferCoder.of(), FlinkPipelineOptions.defaults()));
+                ValueTypeInfo.of(FlinkKey.class));
 
     testHarness.open();
 
     Lock stateBackendLock = Whitebox.getInternalState(operator, "stateBackendLock");
     stateBackendLock.lock();
 
-    KeyedStateBackend<ByteBuffer> keyedStateBackend = operator.getKeyedStateBackend();
-    ByteBuffer key = FlinkKeyUtils.encodeKey(windowedValue.getValue().getKey(), keyCoder);
+    KeyedStateBackend<FlinkKey> keyedStateBackend = operator.getKeyedStateBackend();
+    FlinkKey key = FlinkKey.of(windowedValue.getValue().getKey(), keyCoder);
     keyedStateBackend.setCurrentKey(key);
 
     DoFnOperator.FlinkTimerInternals timerInternals =
@@ -937,13 +938,12 @@ public void testEnsureStateCleanupOnFinalWatermark() throws Exception {
             WindowedValue.getFullCoder(kvCoder, windowCoder));
 
     KeyedOneInputStreamOperatorTestHarness<
-            ByteBuffer, WindowedValue<KV<String, Integer>>, WindowedValue<Integer>>
+            FlinkKey, WindowedValue<KV<String, Integer>>, WindowedValue<Integer>>
         testHarness =
             new KeyedOneInputStreamOperatorTestHarness(
                 operator,
                 operator.keySelector,
-                new CoderTypeInformation<>(
-                    FlinkKeyUtils.ByteBufferCoder.of(), FlinkPipelineOptions.defaults()));
+                ValueTypeInfo.of(FlinkKey.class));
 
     RemoteBundle bundle = Mockito.mock(RemoteBundle.class);
     when(bundle.getInputReceivers())
@@ -955,8 +955,8 @@ public void testEnsureStateCleanupOnFinalWatermark() throws Exception {
 
     testHarness.open();
 
-    KeyedStateBackend<ByteBuffer> keyedStateBackend = operator.getKeyedStateBackend();
-    ByteBuffer key = FlinkKeyUtils.encodeKey("key1", keyCoder);
+    KeyedStateBackend<FlinkKey> keyedStateBackend = operator.getKeyedStateBackend();
+    FlinkKey key = FlinkKey.of("key1", keyCoder);
     keyedStateBackend.setCurrentKey(key);
 
     // create some state which can be cleaned up
@@ -981,7 +981,7 @@ public void testEnsureStateCleanupOnFinalWatermark() throws Exception {
   @Test
   public void testCacheTokenHandling() throws Exception {
     InMemoryStateInternals test = InMemoryStateInternals.forKey("test");
-    KeyedStateBackend<ByteBuffer> stateBackend = FlinkStateInternalsTest.createStateBackend();
+    KeyedStateBackend<FlinkKey> stateBackend = FlinkStateInternalsTest.createStateBackend();
 
     ExecutableStageDoFnOperator.BagUserStateFactory<Integer, GlobalWindow> bagUserStateFactory =
         new ExecutableStageDoFnOperator.BagUserStateFactory<>(
@@ -1254,7 +1254,7 @@ private ExecutableStageDoFnOperator getOperator(
             createOutputMap(mainOutput, additionalOutputs),
             windowingStrategy,
             keyCoder,
-            keyCoder != null ? new KvToByteBufferKeySelector<>(keyCoder, null) : null);
+            keyCoder != null ? new KvToFlinkKeyKeySelector<>(keyCoder) : null);
 
     Whitebox.setInternalState(operator, "stateRequestHandler", stateRequestHandler);
     return operator;
diff --git a/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/WindowDoFnOperatorTest.java b/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/WindowDoFnOperatorTest.java
index 408e8d05a4a0..221a8c458886 100644
--- a/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/WindowDoFnOperatorTest.java
+++ b/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/WindowDoFnOperatorTest.java
@@ -30,10 +30,12 @@
 
 import java.io.ByteArrayOutputStream;
 import java.nio.ByteBuffer;
+
 import org.apache.beam.runners.core.KeyedWorkItem;
 import org.apache.beam.runners.core.SystemReduceFn;
 import org.apache.beam.runners.core.construction.SerializablePipelineOptions;
 import org.apache.beam.runners.flink.FlinkPipelineOptions;
+import org.apache.beam.runners.flink.adapter.FlinkKey;
 import org.apache.beam.runners.flink.translation.wrappers.streaming.DoFnOperator.MultiOutputOutputManagerFactory;
 import org.apache.beam.sdk.coders.Coder;
 import org.apache.beam.sdk.coders.CoderRegistry;
@@ -52,7 +54,7 @@
 import org.apache.beam.sdk.values.WindowingStrategy;
 import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.Iterables;
 import org.apache.flink.api.java.functions.KeySelector;
-import org.apache.flink.api.java.typeutils.GenericTypeInfo;
+import org.apache.flink.api.java.typeutils.ValueTypeInfo;
 import org.apache.flink.runtime.checkpoint.OperatorSubtaskState;
 import org.apache.flink.streaming.runtime.streamrecord.StreamRecord;
 import org.apache.flink.streaming.util.KeyedOneInputStreamOperatorTestHarness;
@@ -73,7 +75,7 @@ public class WindowDoFnOperatorTest {
   public void testRestore() throws Exception {
     // test harness
     KeyedOneInputStreamOperatorTestHarness<
-            ByteBuffer, WindowedValue<KV<Long, Long>>, WindowedValue<KV<Long, Long>>>
+        FlinkKey, WindowedValue<KV<Long, Long>>, WindowedValue<KV<Long, Long>>>
         testHarness = createTestHarness(getWindowDoFnOperator(true));
     testHarness.open();
 
@@ -125,7 +127,7 @@ public void testTimerCleanupOfPendingTimerList() throws Exception {
     // test harness
     WindowDoFnOperator<Long, Long, Long> windowDoFnOperator = getWindowDoFnOperator(true);
     KeyedOneInputStreamOperatorTestHarness<
-            ByteBuffer, WindowedValue<KV<Long, Long>>, WindowedValue<KV<Long, Long>>>
+            FlinkKey, WindowedValue<KV<Long, Long>>, WindowedValue<KV<Long, Long>>>
         testHarness = createTestHarness(windowDoFnOperator);
     testHarness.open();
 
@@ -233,22 +235,22 @@ outputTag, outputCoder, new SerializablePipelineOptions(options)),
         emptyList(),
         options,
         VarLongCoder.of(),
-        new WorkItemKeySelector(VarLongCoder.of(), new SerializablePipelineOptions(options)));
+        new WorkItemKeySelector(VarLongCoder.of()));
   }
 
   private KeyedOneInputStreamOperatorTestHarness<
-          ByteBuffer, WindowedValue<KV<Long, Long>>, WindowedValue<KV<Long, Long>>>
+          FlinkKey, WindowedValue<KV<Long, Long>>, WindowedValue<KV<Long, Long>>>
       createTestHarness(WindowDoFnOperator<Long, Long, Long> windowDoFnOperator) throws Exception {
     return new KeyedOneInputStreamOperatorTestHarness<>(
         windowDoFnOperator,
-        (KeySelector<WindowedValue<KV<Long, Long>>, ByteBuffer>)
+        (KeySelector<WindowedValue<KV<Long, Long>>, FlinkKey>)
             o -> {
               try (ByteArrayOutputStream baos = new ByteArrayOutputStream()) {
                 VarLongCoder.of().encode(o.getValue().getKey(), baos);
-                return ByteBuffer.wrap(baos.toByteArray());
+                return FlinkKey.of(ByteBuffer.wrap(baos.toByteArray()));
               }
             },
-        new GenericTypeInfo<>(ByteBuffer.class));
+        ValueTypeInfo.of(FlinkKey.class));
   }
 
   private static class Item {

From ac24d8f8fa831211a11e55fe5f147dfa500b185e Mon Sep 17 00:00:00 2001
From: jto <boudhevil@gmail.com>
Date: Wed, 16 Oct 2024 20:58:14 +0200
Subject: [PATCH 23/26] [Flink] Add post commit triggers

---
 .../trigger_files/beam_PostCommit_Java_PVR_Flink_Batch.json    | 2 +-
 .../trigger_files/beam_PostCommit_Java_PVR_Flink_Docker.json   | 3 ++-
 .../beam_PostCommit_Java_PVR_Flink_Streaming.json              | 3 ++-
 .github/trigger_files/beam_PostCommit_Python.json              | 3 ++-
 4 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/.github/trigger_files/beam_PostCommit_Java_PVR_Flink_Batch.json b/.github/trigger_files/beam_PostCommit_Java_PVR_Flink_Batch.json
index e3d6056a5de9..c4676f255a44 100644
--- a/.github/trigger_files/beam_PostCommit_Java_PVR_Flink_Batch.json
+++ b/.github/trigger_files/beam_PostCommit_Java_PVR_Flink_Batch.json
@@ -1,4 +1,4 @@
 {
   "comment": "Modify this file in a trivial way to cause this test suite to run",
-  "modification": 1
+  "https://github.com/apache/beam/pull/32440": "test new datastream runner for batch"
 }
diff --git a/.github/trigger_files/beam_PostCommit_Java_PVR_Flink_Docker.json b/.github/trigger_files/beam_PostCommit_Java_PVR_Flink_Docker.json
index b970762c8397..5367806ac338 100644
--- a/.github/trigger_files/beam_PostCommit_Java_PVR_Flink_Docker.json
+++ b/.github/trigger_files/beam_PostCommit_Java_PVR_Flink_Docker.json
@@ -1,4 +1,5 @@
 {
   "comment": "Modify this file in a trivial way to cause this test suite to run",
-  "https://github.com/apache/beam/pull/31156": "noting that PR #31156 should run this test"
+  "https://github.com/apache/beam/pull/31156": "noting that PR #31156 should run this test",
+  "https://github.com/apache/beam/pull/32440": "test new datastream runner for batch"
 }
diff --git a/.github/trigger_files/beam_PostCommit_Java_PVR_Flink_Streaming.json b/.github/trigger_files/beam_PostCommit_Java_PVR_Flink_Streaming.json
index e3d6056a5de9..2dd3a2471d89 100644
--- a/.github/trigger_files/beam_PostCommit_Java_PVR_Flink_Streaming.json
+++ b/.github/trigger_files/beam_PostCommit_Java_PVR_Flink_Streaming.json
@@ -1,4 +1,5 @@
 {
   "comment": "Modify this file in a trivial way to cause this test suite to run",
-  "modification": 1
+  "modification": 1,
+  "https://github.com/apache/beam/pull/32440": "test new datastream runner for batch"
 }
diff --git a/.github/trigger_files/beam_PostCommit_Python.json b/.github/trigger_files/beam_PostCommit_Python.json
index 9e1d1e1b80dd..0e40218bf035 100644
--- a/.github/trigger_files/beam_PostCommit_Python.json
+++ b/.github/trigger_files/beam_PostCommit_Python.json
@@ -1,5 +1,6 @@
 {
   "comment": "Modify this file in a trivial way to cause this test suite to run.",
-  "modification": 4
+  "modification": 4,
+  "https://github.com/apache/beam/pull/32440": "test new datastream runner for batch"
 }
 

From a7b90230ef6cad0deb3f4b095781f5af5e751680 Mon Sep 17 00:00:00 2001
From: jto <boudhevil@gmail.com>
Date: Wed, 16 Oct 2024 21:01:37 +0200
Subject: [PATCH 24/26] [Flink] licence

---
 .../beam/runners/flink/adapter/FlinkKey.java  | 17 +++++++++++++
 .../runners/flink/adapter/FlinkKeyTest.java   | 25 ++++++++++++++-----
 2 files changed, 36 insertions(+), 6 deletions(-)

diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/adapter/FlinkKey.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/adapter/FlinkKey.java
index 637b4cb3696e..cf3871f68a1c 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/adapter/FlinkKey.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/adapter/FlinkKey.java
@@ -1,3 +1,20 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
 package org.apache.beam.runners.flink.adapter;
 
 import org.apache.beam.runners.flink.translation.types.CoderTypeSerializer;
diff --git a/runners/flink/src/test/java/org/apache/beam/runners/flink/adapter/FlinkKeyTest.java b/runners/flink/src/test/java/org/apache/beam/runners/flink/adapter/FlinkKeyTest.java
index 97f9228c8499..b0fadc0c07eb 100644
--- a/runners/flink/src/test/java/org/apache/beam/runners/flink/adapter/FlinkKeyTest.java
+++ b/runners/flink/src/test/java/org/apache/beam/runners/flink/adapter/FlinkKeyTest.java
@@ -1,26 +1,39 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
 package org.apache.beam.runners.flink.adapter;
 
-import com.google.common.collect.Range;
 import org.apache.beam.sdk.coders.VarIntCoder;
 import org.apache.flink.api.common.typeinfo.TypeInformation;
-import org.apache.flink.api.common.typeutils.TypeSerializer;
 import org.apache.flink.api.java.tuple.Tuple2;
 import org.apache.flink.api.java.typeutils.GenericTypeInfo;
 import org.apache.flink.api.java.typeutils.TypeExtractor;
 import org.apache.flink.api.java.typeutils.ValueTypeInfo;
 import org.apache.flink.util.MathUtils;
-import org.hamcrest.Matchers;
-import org.hamcrest.core.IsEqual;
 import org.hamcrest.core.IsInstanceOf;
 import org.junit.Test;
+
 import java.nio.ByteBuffer;
 import java.nio.charset.StandardCharsets;
 import java.util.Set;
 import java.util.stream.Collectors;
 import java.util.stream.IntStream;
-import java.util.stream.Stream;
 
-import static org.hamcrest.MatcherAssert.*;
+import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.greaterThan;
 import static org.hamcrest.Matchers.not;

From ae0f3b4fa84962420302cb6b07f4b69ee770e414 Mon Sep 17 00:00:00 2001
From: jto <boudhevil@gmail.com>
Date: Wed, 16 Oct 2024 21:07:41 +0200
Subject: [PATCH 25/26] [Flink] spotless

---
 ...FlinkStreamingAggregationsTranslators.java | 180 +++++++++---------
 .../FlinkStreamingPipelineTranslator.java     |   1 -
 ...nkStreamingPortablePipelineTranslator.java |   9 +-
 .../FlinkStreamingTransformTranslators.java   |  18 +-
 .../beam/runners/flink/adapter/FlinkKey.java  |  13 +-
 .../ExecutableStageDoFnOperator.java          |  11 +-
 .../streaming/SdfFlinkKeyKeySelector.java     |   7 +-
 .../runners/flink/adapter/FlinkKeyTest.java   |  33 ++--
 .../streaming/FlinkStateInternalsTest.java    |   6 +-
 .../wrappers/streaming/DoFnOperatorTest.java  |  36 +---
 .../ExecutableStageDoFnOperatorTest.java      |   8 +-
 .../streaming/WindowDoFnOperatorTest.java     |   3 +-
 12 files changed, 150 insertions(+), 175 deletions(-)

diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingAggregationsTranslators.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingAggregationsTranslators.java
index 1579a3d4affa..1683ced890c7 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingAggregationsTranslators.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingAggregationsTranslators.java
@@ -17,6 +17,11 @@
  */
 package org.apache.beam.runners.flink;
 
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
 import org.apache.beam.runners.core.KeyedWorkItem;
 import org.apache.beam.runners.core.SystemReduceFn;
 import org.apache.beam.runners.core.construction.SerializablePipelineOptions;
@@ -58,14 +63,9 @@
 import org.apache.flink.streaming.api.transformations.TwoInputTransformation;
 import org.apache.flink.util.Collector;
 
-import java.util.ArrayList;
-import java.util.Collections;
-import java.util.HashMap;
-import java.util.List;
-import java.util.Map;
-
 public class FlinkStreamingAggregationsTranslators {
-  public static class ConcatenateAsIterable<T> extends Combine.CombineFn<T, Iterable<T>, Iterable<T>> {
+  public static class ConcatenateAsIterable<T>
+      extends Combine.CombineFn<T, Iterable<T>, Iterable<T>> {
     @Override
     public Iterable<T> createAccumulator() {
       return new ArrayList<>();
@@ -214,8 +214,7 @@ WindowDoFnOperator<K, InputAccumT, OutputAccumT> getWindowedAggregateDoFnOperato
         WindowedValue.getFullCoder(workItemCoder, windowingStrategy.getWindowFn().windowCoder());
 
     // Key selector
-    WorkItemKeySelector<K, InputAccumT> workItemKeySelector =
-        new WorkItemKeySelector<>(keyCoder);
+    WorkItemKeySelector<K, InputAccumT> workItemKeySelector = new WorkItemKeySelector<>(keyCoder);
 
     return new WindowDoFnOperator<>(
         reduceFn,
@@ -257,29 +256,30 @@ WindowDoFnOperator<K, InputAccumT, OutputAccumT> getWindowedAggregateDoFnOperato
   }
 
   private static class FlattenIterable<K, InputT>
-      implements FlatMapFunction<WindowedValue<KV<K, Iterable<Iterable<InputT>>>>, WindowedValue<KV<K, Iterable<InputT>>>> {
+      implements FlatMapFunction<
+          WindowedValue<KV<K, Iterable<Iterable<InputT>>>>,
+          WindowedValue<KV<K, Iterable<InputT>>>> {
     @Override
     public void flatMap(
         WindowedValue<KV<K, Iterable<Iterable<InputT>>>> w,
-        Collector<WindowedValue<KV<K, Iterable<InputT>>>> collector) throws Exception {
-      WindowedValue<KV<K, Iterable<InputT>>> flattened = w.withValue(
-          KV.of(
-              w.getValue().getKey(),
-              Iterables.concat(w.getValue().getValue())));
+        Collector<WindowedValue<KV<K, Iterable<InputT>>>> collector)
+        throws Exception {
+      WindowedValue<KV<K, Iterable<InputT>>> flattened =
+          w.withValue(KV.of(w.getValue().getKey(), Iterables.concat(w.getValue().getValue())));
       collector.collect(flattened);
     }
   }
 
   public static <K, InputT, AccumT, OutputT>
-    SingleOutputStreamOperator<WindowedValue<KV<K, OutputT>>> getBatchCombinePerKeyOperator(
-        FlinkStreamingTranslationContext context,
-        PCollection<KV<K, InputT>> input,
-        Map<Integer, PCollectionView<?>> sideInputTagMapping,
-        List<PCollectionView<?>> sideInputs,
-        Coder<WindowedValue<KV<K, AccumT>>> windowedAccumCoder,
-        CombineFnBase.GlobalCombineFn<InputT, AccumT, ?> combineFn,
-        WindowDoFnOperator<K, AccumT, OutputT> finalDoFnOperator,
-        TypeInformation<WindowedValue<KV<K, OutputT>>> outputTypeInfo){
+      SingleOutputStreamOperator<WindowedValue<KV<K, OutputT>>> getBatchCombinePerKeyOperator(
+          FlinkStreamingTranslationContext context,
+          PCollection<KV<K, InputT>> input,
+          Map<Integer, PCollectionView<?>> sideInputTagMapping,
+          List<PCollectionView<?>> sideInputs,
+          Coder<WindowedValue<KV<K, AccumT>>> windowedAccumCoder,
+          CombineFnBase.GlobalCombineFn<InputT, AccumT, ?> combineFn,
+          WindowDoFnOperator<K, AccumT, OutputT> finalDoFnOperator,
+          TypeInformation<WindowedValue<KV<K, OutputT>>> outputTypeInfo) {
 
     String fullName = FlinkStreamingTransformTranslators.getCurrentTransformName(context);
     DataStream<WindowedValue<KV<K, InputT>>> inputDataStream = context.getInputDataStream(input);
@@ -314,50 +314,55 @@ SingleOutputStreamOperator<WindowedValue<KV<K, OutputT>>> getBatchCombinePerKeyO
     if (sideInputs.isEmpty()) {
       return inputDataStream
           .transform(partialName, partialTypeInfo, partialDoFnOperator)
-          .uid(partialName).name(partialName)
+          .uid(partialName)
+          .name(partialName)
           .keyBy(accumKeySelector)
           .transform(fullName, outputTypeInfo, finalDoFnOperator)
-          .uid(fullName).name(fullName);
+          .uid(fullName)
+          .name(fullName);
     } else {
 
       Tuple2<Map<Integer, PCollectionView<?>>, DataStream<RawUnionValue>> transformSideInputs =
           FlinkStreamingTransformTranslators.transformSideInputs(sideInputs, context);
 
       TwoInputTransformation<
-          WindowedValue<KV<K, InputT>>, RawUnionValue, WindowedValue<KV<K, AccumT>>> rawPartialFlinkTransform =
-          new TwoInputTransformation<>(
-              inputDataStream.getTransformation(),
-              transformSideInputs.f1.broadcast().getTransformation(),
-              partialName,
-              partialDoFnOperator,
-              partialTypeInfo,
-              inputDataStream.getParallelism());
+              WindowedValue<KV<K, InputT>>, RawUnionValue, WindowedValue<KV<K, AccumT>>>
+          rawPartialFlinkTransform =
+              new TwoInputTransformation<>(
+                  inputDataStream.getTransformation(),
+                  transformSideInputs.f1.broadcast().getTransformation(),
+                  partialName,
+                  partialDoFnOperator,
+                  partialTypeInfo,
+                  inputDataStream.getParallelism());
 
       SingleOutputStreamOperator<WindowedValue<KV<K, AccumT>>> partialyCombinedStream =
           new SingleOutputStreamOperator<WindowedValue<KV<K, AccumT>>>(
               inputDataStream.getExecutionEnvironment(),
               rawPartialFlinkTransform) {}; // we have to cheat around the ctor being protected
 
-        inputDataStream.getExecutionEnvironment().addOperator(rawPartialFlinkTransform);
+      inputDataStream.getExecutionEnvironment().addOperator(rawPartialFlinkTransform);
 
-        return buildTwoInputStream(
-            partialyCombinedStream.keyBy(accumKeySelector),
-            transformSideInputs.f1,
-            fullName,
-            finalDoFnOperator,
-            outputTypeInfo);
+      return buildTwoInputStream(
+          partialyCombinedStream.keyBy(accumKeySelector),
+          transformSideInputs.f1,
+          fullName,
+          finalDoFnOperator,
+          outputTypeInfo);
     }
   }
 
   /**
-   * Creates a two-steps GBK operation. Elements are first aggregated locally to save on serialized size since in batch
-   * it's very likely that all the elements will be within the same window and pane.
-   * The only difference with batchCombinePerKey is the nature of the SystemReduceFn used. It uses SystemReduceFn.buffering()
-   * instead of SystemReduceFn.combining() so that new element can simply be appended without accessing the existing state.
+   * Creates a two-steps GBK operation. Elements are first aggregated locally to save on serialized
+   * size since in batch it's very likely that all the elements will be within the same window and
+   * pane. The only difference with batchCombinePerKey is the nature of the SystemReduceFn used. It
+   * uses SystemReduceFn.buffering() instead of SystemReduceFn.combining() so that new element can
+   * simply be appended without accessing the existing state.
    */
-  public static <K, InputT> SingleOutputStreamOperator<WindowedValue<KV<K, Iterable<InputT>>>> batchGroupByKey(
-      FlinkStreamingTranslationContext context,
-      PTransform<PCollection<KV<K, InputT>>, PCollection<KV<K, Iterable<InputT>>>> transform) {
+  public static <K, InputT>
+      SingleOutputStreamOperator<WindowedValue<KV<K, Iterable<InputT>>>> batchGroupByKey(
+          FlinkStreamingTranslationContext context,
+          PTransform<PCollection<KV<K, InputT>>, PCollection<KV<K, Iterable<InputT>>>> transform) {
 
     Map<Integer, PCollectionView<?>> sideInputTagMapping = new HashMap<>();
     List<PCollectionView<?>> sideInputs = Collections.emptyList();
@@ -372,7 +377,8 @@ public static <K, InputT> SingleOutputStreamOperator<WindowedValue<KV<K, Iterabl
         context.getTypeInfo(context.getOutput(transform));
 
     Coder<Iterable<InputT>> accumulatorCoder = IterableCoder.of(inputKvCoder.getValueCoder());
-    KvCoder<K, Iterable<InputT>> accumKvCoder = KvCoder.of(inputKvCoder.getKeyCoder(), accumulatorCoder);
+    KvCoder<K, Iterable<InputT>> accumKvCoder =
+        KvCoder.of(inputKvCoder.getKeyCoder(), accumulatorCoder);
 
     Coder<WindowedValue<KV<K, Iterable<InputT>>>> windowedAccumCoder =
         WindowedValue.getFullCoder(
@@ -380,50 +386,55 @@ public static <K, InputT> SingleOutputStreamOperator<WindowedValue<KV<K, Iterabl
 
     Coder<WindowedValue<KV<K, Iterable<Iterable<InputT>>>>> outputCoder =
         WindowedValue.getFullCoder(
-            KvCoder.of(inputKvCoder.getKeyCoder(), IterableCoder.of(accumulatorCoder)) , input.getWindowingStrategy().getWindowFn().windowCoder());
+            KvCoder.of(inputKvCoder.getKeyCoder(), IterableCoder.of(accumulatorCoder)),
+            input.getWindowingStrategy().getWindowFn().windowCoder());
 
     TypeInformation<WindowedValue<KV<K, Iterable<Iterable<InputT>>>>> accumulatedTypeInfo =
         new CoderTypeInformation<>(
-          WindowedValue.getFullCoder(
-              KvCoder.of(inputKvCoder.getKeyCoder(), IterableCoder.of(IterableCoder.of(inputKvCoder.getValueCoder()))), input.getWindowingStrategy().getWindowFn().windowCoder()),
+            WindowedValue.getFullCoder(
+                KvCoder.of(
+                    inputKvCoder.getKeyCoder(),
+                    IterableCoder.of(IterableCoder.of(inputKvCoder.getValueCoder()))),
+                input.getWindowingStrategy().getWindowFn().windowCoder()),
             serializablePipelineOptions);
 
     // final aggregation
     WindowDoFnOperator<K, Iterable<InputT>, Iterable<Iterable<InputT>>> finalDoFnOperator =
-          getWindowedAccumulateDoFnOperator(
-              context,
-              transform,
-              accumKvCoder,
-              outputCoder,
-              sideInputTagMapping,
-              sideInputs);
-
-    return
-        getBatchCombinePerKeyOperator(
-          context,
-          input,
-          sideInputTagMapping,
-          sideInputs,
-          windowedAccumCoder,
-          new ConcatenateAsIterable<>(),
-          finalDoFnOperator,
-          accumulatedTypeInfo
-      )
-      .flatMap(new FlattenIterable<>(), outputTypeInfo)
-      .name("concatenate");
+        getWindowedAccumulateDoFnOperator(
+            context, transform, accumKvCoder, outputCoder, sideInputTagMapping, sideInputs);
+
+    return getBatchCombinePerKeyOperator(
+            context,
+            input,
+            sideInputTagMapping,
+            sideInputs,
+            windowedAccumCoder,
+            new ConcatenateAsIterable<>(),
+            finalDoFnOperator,
+            accumulatedTypeInfo)
+        .flatMap(new FlattenIterable<>(), outputTypeInfo)
+        .name("concatenate");
   }
 
-  private static <InputT, K> WindowDoFnOperator<K, Iterable<InputT>, Iterable<Iterable<InputT>>> getWindowedAccumulateDoFnOperator(
-      FlinkStreamingTranslationContext context,
-      PTransform<PCollection<KV<K,InputT>>, PCollection<KV<K, Iterable<InputT>>>> transform,
-      KvCoder<K, Iterable<InputT>> accumKvCoder,
-      Coder<WindowedValue<KV<K, Iterable<Iterable<InputT>>>>> outputCoder,
-      Map<Integer, PCollectionView<?>> sideInputTagMapping,
-      List<PCollectionView<?>> sideInputs) {
+  private static <InputT, K>
+      WindowDoFnOperator<K, Iterable<InputT>, Iterable<Iterable<InputT>>>
+          getWindowedAccumulateDoFnOperator(
+              FlinkStreamingTranslationContext context,
+              PTransform<PCollection<KV<K, InputT>>, PCollection<KV<K, Iterable<InputT>>>>
+                  transform,
+              KvCoder<K, Iterable<InputT>> accumKvCoder,
+              Coder<WindowedValue<KV<K, Iterable<Iterable<InputT>>>>> outputCoder,
+              Map<Integer, PCollectionView<?>> sideInputTagMapping,
+              List<PCollectionView<?>> sideInputs) {
 
-      // Combining fn
-    SystemReduceFn<K, Iterable<InputT>, Iterable<Iterable<InputT>>, Iterable<Iterable<InputT>>, BoundedWindow> reduceFn =
-        SystemReduceFn.buffering(accumKvCoder.getValueCoder());
+    // Combining fn
+    SystemReduceFn<
+            K,
+            Iterable<InputT>,
+            Iterable<Iterable<InputT>>,
+            Iterable<Iterable<InputT>>,
+            BoundedWindow>
+        reduceFn = SystemReduceFn.buffering(accumKvCoder.getValueCoder());
 
     return getWindowedAggregateDoFnOperator(
         context, transform, accumKvCoder, outputCoder, reduceFn, sideInputTagMapping, sideInputs);
@@ -482,8 +493,7 @@ SingleOutputStreamOperator<WindowedValue<KV<K, OutputT>>> batchCombinePerKey(
         windowedAccumCoder,
         combineFn,
         finalDoFnOperator,
-        outputTypeInfo
-    );
+        outputTypeInfo);
   }
 
   @SuppressWarnings({
diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingPipelineTranslator.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingPipelineTranslator.java
index 8f0e6db26dab..0607838987f1 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingPipelineTranslator.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingPipelineTranslator.java
@@ -27,7 +27,6 @@
 import java.util.Objects;
 import java.util.concurrent.ThreadLocalRandom;
 import java.util.concurrent.TimeUnit;
-
 import org.apache.beam.runners.flink.adapter.FlinkKey;
 import org.apache.beam.sdk.Pipeline;
 import org.apache.beam.sdk.coders.Coder;
diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingPortablePipelineTranslator.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingPortablePipelineTranslator.java
index 901ab1c672dc..a74be9f7e9e0 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingPortablePipelineTranslator.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingPortablePipelineTranslator.java
@@ -434,8 +434,7 @@ private <K, V> SingleOutputStreamOperator<WindowedValue<KV<K, Iterable<V>>>> add
         new WorkItemKeySelector<>(inputElementCoder.getKeyCoder());
 
     KeyedStream<WindowedValue<KV<K, V>>, FlinkKey> keyedWorkItemStream =
-        inputDataStream.keyBy(
-            new KvToFlinkKeyKeySelector(inputElementCoder.getKeyCoder()));
+        inputDataStream.keyBy(new KvToFlinkKeyKeySelector(inputElementCoder.getKeyCoder()));
 
     SystemReduceFn<K, V, Iterable<V>, Iterable<V>, BoundedWindow> reduceFn =
         SystemReduceFn.buffering(inputElementCoder.getValueCoder());
@@ -829,8 +828,7 @@ private <InputT, OutputT> void translateExecutableStage(
       }
       if (stateful) {
         keyCoder = ((KvCoder) valueCoder).getKeyCoder();
-        keySelector =
-            new KvToFlinkKeyKeySelector(keyCoder);
+        keySelector = new KvToFlinkKeyKeySelector(keyCoder);
       } else {
         // For an SDF, we know that the input element should be
         // KV<KV<element, KV<restriction, watermarkState>>, size>. We are going to use the element
@@ -844,8 +842,7 @@ private <InputT, OutputT> void translateExecutableStage(
                   valueCoder.getClass().getSimpleName()));
         }
         keyCoder = ((KvCoder) ((KvCoder) valueCoder).getKeyCoder()).getKeyCoder();
-        keySelector =
-            new SdfFlinkKeyKeySelector(keyCoder);
+        keySelector = new SdfFlinkKeyKeySelector(keyCoder);
       }
       inputDataStream = inputDataStream.keyBy(keySelector);
     }
diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingTransformTranslators.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingTransformTranslators.java
index 35a08eb54115..36cf035a33be 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingTransformTranslators.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/FlinkStreamingTransformTranslators.java
@@ -105,7 +105,6 @@
 import org.apache.flink.api.common.typeinfo.TypeInformation;
 import org.apache.flink.api.java.functions.KeySelector;
 import org.apache.flink.api.java.tuple.Tuple2;
-import org.apache.flink.api.java.typeutils.GenericTypeInfo;
 import org.apache.flink.api.java.typeutils.ResultTypeQueryable;
 import org.apache.flink.api.java.typeutils.ValueTypeInfo;
 import org.apache.flink.configuration.Configuration;
@@ -591,8 +590,7 @@ static <InputT, OutputT> void translateParDo(
         // Based on the fact that the signature is stateful, DoFnSignatures ensures
         // that it is also keyed
         keyCoder = ((KvCoder) input.getCoder()).getKeyCoder();
-        keySelector =
-            new KvToFlinkKeyKeySelector<>(keyCoder);
+        keySelector = new KvToFlinkKeyKeySelector<>(keyCoder);
         final PTransform<?, PCollection<InputT>> producer = context.getProducer(input);
         final String previousUrn =
             producer != null
@@ -609,8 +607,7 @@ static <InputT, OutputT> void translateParDo(
       } else if (doFn instanceof SplittableParDoViaKeyedWorkItems.ProcessFn) {
         // we know that it is keyed on byte[]
         keyCoder = ByteArrayCoder.of();
-        keySelector =
-            new WorkItemKeySelector<>(keyCoder);
+        keySelector = new WorkItemKeySelector<>(keyCoder);
         stateful = true;
       }
 
@@ -962,10 +959,7 @@ public void translateNode(
       SingleOutputStreamOperator<WindowedValue<KV<K, Iterable<InputT>>>> outDataStream;
       // Pre-aggregate before shuffle similar to group combine
       if (!context.isStreaming()) {
-        outDataStream =
-            FlinkStreamingAggregationsTranslators.batchGroupByKey(
-                context,
-                transform);
+        outDataStream = FlinkStreamingAggregationsTranslators.batchGroupByKey(context, transform);
       } else {
         // No pre-aggregation in Streaming mode.
         KvToFlinkKeyKeySelector<K, InputT> keySelector =
@@ -1046,8 +1040,7 @@ public void translateNode(
       List<PCollectionView<?>> sideInputs = ((Combine.PerKey) transform).getSideInputs();
 
       KeyedStream<WindowedValue<KV<K, InputT>>, FlinkKey> keyedStream =
-          inputDataStream.keyBy(
-              new KvToFlinkKeyKeySelector<>(keyCoder));
+          inputDataStream.keyBy(new KvToFlinkKeyKeySelector<>(keyCoder));
 
       if (sideInputs.isEmpty()) {
         SingleOutputStreamOperator<WindowedValue<KV<K, OutputT>>> outDataStream;
@@ -1147,8 +1140,7 @@ public void translateNode(
               .name("ToKeyedWorkItem");
 
       KeyedStream<WindowedValue<KeyedWorkItem<K, InputT>>, FlinkKey> keyedWorkItemStream =
-          workItemStream.keyBy(
-              new WorkItemKeySelector<>(inputKvCoder.getKeyCoder()));
+          workItemStream.keyBy(new WorkItemKeySelector<>(inputKvCoder.getKeyCoder()));
 
       context.setOutputDataStream(context.getOutput(transform), keyedWorkItemStream);
     }
diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/adapter/FlinkKey.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/adapter/FlinkKey.java
index cf3871f68a1c..6a5e8d0458f3 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/adapter/FlinkKey.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/adapter/FlinkKey.java
@@ -17,6 +17,11 @@
  */
 package org.apache.beam.runners.flink.adapter;
 
+import static org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.base.Preconditions.checkNotNull;
+
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import javax.annotation.Nullable;
 import org.apache.beam.runners.flink.translation.types.CoderTypeSerializer;
 import org.apache.beam.runners.flink.translation.wrappers.streaming.FlinkKeyUtils;
 import org.apache.beam.sdk.coders.ByteArrayCoder;
@@ -26,12 +31,6 @@
 import org.apache.flink.core.memory.DataOutputView;
 import org.apache.flink.types.Value;
 
-import javax.annotation.Nullable;
-import java.io.IOException;
-import java.nio.ByteBuffer;
-
-import static org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.base.Preconditions.checkNotNull;
-
 public class FlinkKey implements Value {
 
   private final CoderTypeSerializer<byte[]> serializer;
@@ -77,7 +76,7 @@ public <K> K getKey(Coder<K> coder) {
 
   @Override
   public int hashCode() {
-//    return underlying.hashCode();
+    //    return underlying.hashCode();
     return Hashing.murmur3_128().hashBytes(underlying.array()).asInt();
   }
 
diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/ExecutableStageDoFnOperator.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/ExecutableStageDoFnOperator.java
index c02d7d9c99ea..53e09f3f818c 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/ExecutableStageDoFnOperator.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/ExecutableStageDoFnOperator.java
@@ -562,8 +562,7 @@ class SdfFlinkTimerInternalsFactory implements TimerInternalsFactory<InputT> {
     @Override
     public TimerInternals timerInternalsForKey(InputT key) {
       try {
-        FlinkKey encodedKey =
-            (FlinkKey) keySelector.getKey(WindowedValue.valueInGlobalWindow(key));
+        FlinkKey encodedKey = (FlinkKey) keySelector.getKey(WindowedValue.valueInGlobalWindow(key));
         return new SdfFlinkTimerInternals(encodedKey);
       } catch (Exception e) {
         throw new RuntimeException("Couldn't get a timer internals", e);
@@ -659,8 +658,7 @@ class SdfFlinkStateInternalsFactory implements StateInternalsFactory<InputT> {
     @Override
     public StateInternals stateInternalsForKey(InputT key) {
       try {
-        FlinkKey encodedKey =
-            (FlinkKey) keySelector.getKey(WindowedValue.valueInGlobalWindow(key));
+        FlinkKey encodedKey = (FlinkKey) keySelector.getKey(WindowedValue.valueInGlobalWindow(key));
         return new SdfFlinkStateInternals(encodedKey);
       } catch (Exception e) {
         throw new RuntimeException("Couldn't get a state internals", e);
@@ -1259,7 +1257,10 @@ void cleanupState(StateInternals stateInternals, Consumer<FlinkKey> keyContextCo
           cleanupTimer.setCleanupTimer(window);
         } else {
           if (LOG.isDebugEnabled()) {
-            LOG.debug("State cleanup for {} {}", Arrays.toString(kv.getKey().getSerializedKey().array()), window);
+            LOG.debug(
+                "State cleanup for {} {}",
+                Arrays.toString(kv.getKey().getSerializedKey().array()),
+                window);
           }
           // No more timers (finally!). Time to clean up.
           for (String userState : userStateNames) {
diff --git a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/SdfFlinkKeyKeySelector.java b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/SdfFlinkKeyKeySelector.java
index 176a585e993d..b316726e74f8 100644
--- a/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/SdfFlinkKeyKeySelector.java
+++ b/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/SdfFlinkKeyKeySelector.java
@@ -17,10 +17,7 @@
  */
 package org.apache.beam.runners.flink.translation.wrappers.streaming;
 
-import java.nio.ByteBuffer;
-import org.apache.beam.runners.core.construction.SerializablePipelineOptions;
 import org.apache.beam.runners.flink.adapter.FlinkKey;
-import org.apache.beam.runners.flink.translation.types.CoderTypeInformation;
 import org.apache.beam.sdk.coders.Coder;
 import org.apache.beam.sdk.util.WindowedValue;
 import org.apache.beam.sdk.values.KV;
@@ -32,8 +29,8 @@
 /**
  * {@link KeySelector} that retrieves a key from a {@code KV<KV<element, KV<restriction,
  * watermarkState>>, size>}. This will return the element as encoded by the provided {@link Coder}
- * in a {@link FlinkKey}. This ensures that all key comparisons/hashing happen on the encoded
- * form. Note that the reason we don't use the whole {@code KV<KV<element, KV<restriction,
+ * in a {@link FlinkKey}. This ensures that all key comparisons/hashing happen on the encoded form.
+ * Note that the reason we don't use the whole {@code KV<KV<element, KV<restriction,
  * watermarkState>>, Double>} as the key is when checkpoint happens, we will get different
  * restriction/watermarkState/size, which Flink treats as a new key. Using new key to set state and
  * timer may cause defined behavior.
diff --git a/runners/flink/src/test/java/org/apache/beam/runners/flink/adapter/FlinkKeyTest.java b/runners/flink/src/test/java/org/apache/beam/runners/flink/adapter/FlinkKeyTest.java
index b0fadc0c07eb..649332c1e48f 100644
--- a/runners/flink/src/test/java/org/apache/beam/runners/flink/adapter/FlinkKeyTest.java
+++ b/runners/flink/src/test/java/org/apache/beam/runners/flink/adapter/FlinkKeyTest.java
@@ -17,6 +17,16 @@
  */
 package org.apache.beam.runners.flink.adapter;
 
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.equalTo;
+import static org.hamcrest.Matchers.greaterThan;
+import static org.hamcrest.Matchers.not;
+
+import java.nio.ByteBuffer;
+import java.nio.charset.StandardCharsets;
+import java.util.Set;
+import java.util.stream.Collectors;
+import java.util.stream.IntStream;
 import org.apache.beam.sdk.coders.VarIntCoder;
 import org.apache.flink.api.common.typeinfo.TypeInformation;
 import org.apache.flink.api.java.tuple.Tuple2;
@@ -27,17 +37,6 @@
 import org.hamcrest.core.IsInstanceOf;
 import org.junit.Test;
 
-import java.nio.ByteBuffer;
-import java.nio.charset.StandardCharsets;
-import java.util.Set;
-import java.util.stream.Collectors;
-import java.util.stream.IntStream;
-
-import static org.hamcrest.MatcherAssert.assertThat;
-import static org.hamcrest.Matchers.equalTo;
-import static org.hamcrest.Matchers.greaterThan;
-import static org.hamcrest.Matchers.not;
-
 public class FlinkKeyTest {
   @Test
   public void testIsRecognizedAsValue() {
@@ -48,7 +47,8 @@ public void testIsRecognizedAsValue() {
 
     assertThat(tpe, IsInstanceOf.instanceOf(ValueTypeInfo.class));
 
-    TypeInformation<Tuple2<FlinkKey, byte[]>> tupleTpe = TypeExtractor.getForObject(Tuple2.of(key, bs));
+    TypeInformation<Tuple2<FlinkKey, byte[]>> tupleTpe =
+        TypeExtractor.getForObject(Tuple2.of(key, bs));
     assertThat(tupleTpe, not(IsInstanceOf.instanceOf(GenericTypeInfo.class)));
   }
 
@@ -67,10 +67,11 @@ public void testIsConsistent() {
   private void checkDistribution(int numKeys) {
     int paralellism = 2100;
 
-    Set<Integer> hashcodes = IntStream.range(0, numKeys)
-        .mapToObj(i -> FlinkKey.of(i, VarIntCoder.of()))
-        .map(k -> k.hashCode())
-        .collect(Collectors.toSet());
+    Set<Integer> hashcodes =
+        IntStream.range(0, numKeys)
+            .mapToObj(i -> FlinkKey.of(i, VarIntCoder.of()))
+            .map(k -> k.hashCode())
+            .collect(Collectors.toSet());
 
     Set<Integer> keyGroups =
         hashcodes.stream()
diff --git a/runners/flink/src/test/java/org/apache/beam/runners/flink/streaming/FlinkStateInternalsTest.java b/runners/flink/src/test/java/org/apache/beam/runners/flink/streaming/FlinkStateInternalsTest.java
index 95c255159e6f..2324a262acc0 100644
--- a/runners/flink/src/test/java/org/apache/beam/runners/flink/streaming/FlinkStateInternalsTest.java
+++ b/runners/flink/src/test/java/org/apache/beam/runners/flink/streaming/FlinkStateInternalsTest.java
@@ -40,7 +40,6 @@
 import org.apache.beam.sdk.util.CoderUtils;
 import org.apache.flink.api.common.ExecutionConfig;
 import org.apache.flink.api.common.JobID;
-import org.apache.flink.api.java.typeutils.GenericTypeInfo;
 import org.apache.flink.api.java.typeutils.ValueTypeInfo;
 import org.apache.flink.core.fs.CloseableRegistry;
 import org.apache.flink.runtime.jobgraph.JobVertexID;
@@ -212,7 +211,8 @@ public static KeyedStateBackend<FlinkKey> createStateBackend() throws Exception
   private static void changeKey(KeyedStateBackend<FlinkKey> keyedStateBackend)
       throws CoderException {
     keyedStateBackend.setCurrentKey(
-        FlinkKey.of(ByteBuffer.wrap(
-            CoderUtils.encodeToByteArray(StringUtf8Coder.of(), UUID.randomUUID().toString()))));
+        FlinkKey.of(
+            ByteBuffer.wrap(
+                CoderUtils.encodeToByteArray(StringUtf8Coder.of(), UUID.randomUUID().toString()))));
   }
 }
diff --git a/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/DoFnOperatorTest.java b/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/DoFnOperatorTest.java
index 7db97769d97a..f0d8816bdeab 100644
--- a/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/DoFnOperatorTest.java
+++ b/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/DoFnOperatorTest.java
@@ -376,9 +376,7 @@ public void onProcessingTime(OnTimerContext context) {
 
     OneInputStreamOperatorTestHarness<WindowedValue<Integer>, WindowedValue<String>> testHarness =
         new KeyedOneInputStreamOperatorTestHarness<>(
-            doFnOperator,
-            keySelector,
-            ValueTypeInfo.of(FlinkKey.class));
+            doFnOperator, keySelector, ValueTypeInfo.of(FlinkKey.class));
 
     testHarness.setup(
         new CoderTypeSerializer<>(
@@ -544,9 +542,7 @@ void emitWatermarkIfHoldChanged(long currentWatermarkHold) {
             WindowedValue<KV<String, String>>, WindowedValue<KV<String, String>>>
         testHarness =
             new KeyedOneInputStreamOperatorTestHarness<>(
-                doFnOperator,
-                keySelector,
-                ValueTypeInfo.of(FlinkKey.class));
+                doFnOperator, keySelector, ValueTypeInfo.of(FlinkKey.class));
 
     testHarness.setup();
 
@@ -638,9 +634,7 @@ public void processElement(ProcessContext context) {
 
     OneInputStreamOperatorTestHarness<WindowedValue<Integer>, WindowedValue<String>> testHarness =
         new KeyedOneInputStreamOperatorTestHarness<>(
-            doFnOperator,
-            keySelector,
-            ValueTypeInfo.of(FlinkKey.class));
+            doFnOperator, keySelector, ValueTypeInfo.of(FlinkKey.class));
 
     testHarness.open();
 
@@ -887,9 +881,7 @@ outputTag, coder, new SerializablePipelineOptions(options)),
             Collections.emptyMap());
 
     return new KeyedOneInputStreamOperatorTestHarness<>(
-        doFnOperator,
-        keySelector,
-        ValueTypeInfo.of(FlinkKey.class));
+        doFnOperator, keySelector, ValueTypeInfo.of(FlinkKey.class));
   }
 
   @Test
@@ -943,10 +935,7 @@ outputTag, coder, new SerializablePipelineOptions(FlinkPipelineOptions.defaults(
       // we use a dummy key for the second input since it is considered to be broadcast
       testHarness =
           new KeyedTwoInputStreamOperatorTestHarness<>(
-              doFnOperator,
-              keySelector,
-              null,
-              ValueTypeInfo.of(FlinkKey.class));
+              doFnOperator, keySelector, null, ValueTypeInfo.of(FlinkKey.class));
     }
 
     testHarness.open();
@@ -1035,16 +1024,14 @@ public void processElement(
     TupleTag<KV<String, Long>> outputTag = new TupleTag<>("main-output");
 
     StringUtf8Coder keyCoder = StringUtf8Coder.of();
-    KvToFlinkKeyKeySelector<String, Long> keySelector =
-        new KvToFlinkKeyKeySelector<>(keyCoder);
+    KvToFlinkKeyKeySelector<String, Long> keySelector = new KvToFlinkKeyKeySelector<>(keyCoder);
 
     KvCoder<String, Long> coder = KvCoder.of(keyCoder, VarLongCoder.of());
 
     FullWindowedValueCoder<KV<String, Long>> kvCoder =
         WindowedValue.getFullCoder(coder, windowingStrategy.getWindowFn().windowCoder());
 
-    TypeInformation<FlinkKey> keyCoderInfo =
-        ValueTypeInfo.of(FlinkKey.class);
+    TypeInformation<FlinkKey> keyCoderInfo = ValueTypeInfo.of(FlinkKey.class);
 
     OneInputStreamOperatorTestHarness<
             WindowedValue<KV<String, Long>>, WindowedValue<KV<String, Long>>>
@@ -1666,8 +1653,7 @@ public void finishBundle(FinishBundleContext context) {
   public void testBundleKeyed() throws Exception {
 
     StringUtf8Coder keyCoder = StringUtf8Coder.of();
-    KvToFlinkKeyKeySelector<String, String> keySelector =
-        new KvToFlinkKeyKeySelector<>(keyCoder);
+    KvToFlinkKeyKeySelector<String, String> keySelector = new KvToFlinkKeyKeySelector<>(keyCoder);
     KvCoder<String, String> kvCoder = KvCoder.of(keyCoder, StringUtf8Coder.of());
     WindowedValue.ValueOnlyWindowedValueCoder<KV<String, String>> windowedValueCoder =
         WindowedValue.getValueOnlyCoder(kvCoder);
@@ -2114,8 +2100,7 @@ public void testExactlyOnceBufferingKeyed() throws Exception {
     TupleTag<KV<String, String>> outputTag = new TupleTag<>("main-output");
 
     StringUtf8Coder keyCoder = StringUtf8Coder.of();
-    KvToFlinkKeyKeySelector<String, String> keySelector =
-        new KvToFlinkKeyKeySelector<>(keyCoder);
+    KvToFlinkKeyKeySelector<String, String> keySelector = new KvToFlinkKeyKeySelector<>(keyCoder);
     KvCoder<String, String> kvCoder = KvCoder.of(keyCoder, StringUtf8Coder.of());
     WindowedValue.ValueOnlyWindowedValueCoder<KV<String, String>> windowedValueCoder =
         WindowedValue.getValueOnlyCoder(kvCoder);
@@ -2246,8 +2231,7 @@ public void testFailOnRequiresStableInputAndDisabledCheckpointing() {
     TupleTag<KV<String, String>> outputTag = new TupleTag<>("main-output");
 
     StringUtf8Coder keyCoder = StringUtf8Coder.of();
-    KvToFlinkKeyKeySelector<String, String> keySelector =
-        new KvToFlinkKeyKeySelector<>(keyCoder);
+    KvToFlinkKeyKeySelector<String, String> keySelector = new KvToFlinkKeyKeySelector<>(keyCoder);
     KvCoder<String, String> kvCoder = KvCoder.of(keyCoder, StringUtf8Coder.of());
     WindowedValue.ValueOnlyWindowedValueCoder<KV<String, String>> windowedValueCoder =
         WindowedValue.getValueOnlyCoder(kvCoder);
diff --git a/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/ExecutableStageDoFnOperatorTest.java b/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/ExecutableStageDoFnOperatorTest.java
index 68cffda38e36..a0a955aea1d6 100644
--- a/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/ExecutableStageDoFnOperatorTest.java
+++ b/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/ExecutableStageDoFnOperatorTest.java
@@ -791,9 +791,7 @@ private void testEnsureDeferredStateCleanupTimerFiring(boolean withCheckpointing
             FlinkKey, WindowedValue<KV<String, Integer>>, WindowedValue<Integer>>
         testHarness =
             new KeyedOneInputStreamOperatorTestHarness(
-                operator,
-                operator.keySelector,
-                ValueTypeInfo.of(FlinkKey.class));
+                operator, operator.keySelector, ValueTypeInfo.of(FlinkKey.class));
 
     testHarness.open();
 
@@ -941,9 +939,7 @@ public void testEnsureStateCleanupOnFinalWatermark() throws Exception {
             FlinkKey, WindowedValue<KV<String, Integer>>, WindowedValue<Integer>>
         testHarness =
             new KeyedOneInputStreamOperatorTestHarness(
-                operator,
-                operator.keySelector,
-                ValueTypeInfo.of(FlinkKey.class));
+                operator, operator.keySelector, ValueTypeInfo.of(FlinkKey.class));
 
     RemoteBundle bundle = Mockito.mock(RemoteBundle.class);
     when(bundle.getInputReceivers())
diff --git a/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/WindowDoFnOperatorTest.java b/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/WindowDoFnOperatorTest.java
index 221a8c458886..6380108ddb94 100644
--- a/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/WindowDoFnOperatorTest.java
+++ b/runners/flink/src/test/java/org/apache/beam/runners/flink/translation/wrappers/streaming/WindowDoFnOperatorTest.java
@@ -30,7 +30,6 @@
 
 import java.io.ByteArrayOutputStream;
 import java.nio.ByteBuffer;
-
 import org.apache.beam.runners.core.KeyedWorkItem;
 import org.apache.beam.runners.core.SystemReduceFn;
 import org.apache.beam.runners.core.construction.SerializablePipelineOptions;
@@ -75,7 +74,7 @@ public class WindowDoFnOperatorTest {
   public void testRestore() throws Exception {
     // test harness
     KeyedOneInputStreamOperatorTestHarness<
-        FlinkKey, WindowedValue<KV<Long, Long>>, WindowedValue<KV<Long, Long>>>
+            FlinkKey, WindowedValue<KV<Long, Long>>, WindowedValue<KV<Long, Long>>>
         testHarness = createTestHarness(getWindowDoFnOperator(true));
     testHarness.open();
 

From 9738b01f75315e13adafd02c208932bc70c5894e Mon Sep 17 00:00:00 2001
From: Kenneth Knowles <klk@google.com>
Date: Fri, 18 Oct 2024 13:20:10 -0400
Subject: [PATCH 26/26] Additional Flink github action trigger files

---
 .github/trigger_files/beam_PostCommit_Go_VR_Flink.json         | 1 +
 .github/trigger_files/beam_PostCommit_Java_Examples_Flink.json | 3 ++-
 .../beam_PostCommit_Java_ValidatesRunner_Flink.json            | 1 +
 .github/trigger_files/beam_PostCommit_XVR_Flink.json           | 1 +
 4 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/.github/trigger_files/beam_PostCommit_Go_VR_Flink.json b/.github/trigger_files/beam_PostCommit_Go_VR_Flink.json
index b98aece75634..d5ac7fc60d7f 100644
--- a/.github/trigger_files/beam_PostCommit_Go_VR_Flink.json
+++ b/.github/trigger_files/beam_PostCommit_Go_VR_Flink.json
@@ -1,5 +1,6 @@
 {
   "comment": "Modify this file in a trivial way to cause this test suite to run",
   "modification": 1,
+  "https://github.com/apache/beam/pull/32440": "testing datastream optimizations",
   "https://github.com/apache/beam/pull/32648": "testing addition of Flink 1.19 support"
 }
diff --git a/.github/trigger_files/beam_PostCommit_Java_Examples_Flink.json b/.github/trigger_files/beam_PostCommit_Java_Examples_Flink.json
index dd9afb90e638..300fbf52b011 100644
--- a/.github/trigger_files/beam_PostCommit_Java_Examples_Flink.json
+++ b/.github/trigger_files/beam_PostCommit_Java_Examples_Flink.json
@@ -1,3 +1,4 @@
 {
-    "https://github.com/apache/beam/pull/32648": "testing flink 1.19 support"
+  "https://github.com/apache/beam/pull/32440": "testing datastream optimizations",
+  "https://github.com/apache/beam/pull/32648": "testing flink 1.19 support"
 }
diff --git a/.github/trigger_files/beam_PostCommit_Java_ValidatesRunner_Flink.json b/.github/trigger_files/beam_PostCommit_Java_ValidatesRunner_Flink.json
index 9200c368abbe..cb7966397921 100644
--- a/.github/trigger_files/beam_PostCommit_Java_ValidatesRunner_Flink.json
+++ b/.github/trigger_files/beam_PostCommit_Java_ValidatesRunner_Flink.json
@@ -1,5 +1,6 @@
 {
   "comment": "Modify this file in a trivial way to cause this test suite to run",
   "https://github.com/apache/beam/pull/31156": "noting that PR #31156 should run this test",
+  "https://github.com/apache/beam/pull/32440": "testing datastream optimizations",
   "https://github.com/apache/beam/pull/32648": "testing addition of Flink 1.19 support"
 }
diff --git a/.github/trigger_files/beam_PostCommit_XVR_Flink.json b/.github/trigger_files/beam_PostCommit_XVR_Flink.json
index 0b34d452d42c..bb1b9f4c25e9 100644
--- a/.github/trigger_files/beam_PostCommit_XVR_Flink.json
+++ b/.github/trigger_files/beam_PostCommit_XVR_Flink.json
@@ -1,3 +1,4 @@
 {
+  "https://github.com/apache/beam/pull/32440": "testing datastream optimizations",
   "https://github.com/apache/beam/pull/32648": "testing addition of Flink 1.19 support"
 }