Adds automatic cleanup of Spark work directory

Spark uses the 'work' directory to save files (job-jar, ...) required to
run. Per default theses files are never deleted, which can cause quite
heavy memory consumption.

This commit enables a periodic cleanup of the folder during the
execution of an suite/exp (set in the reference.spark.conf) plus an
manual cleanup on startup.

peel-extensions/src/main/resources/reference.spark.conf

@@ -8,6 +8,7 @@ system {
             home = ${app.path.systems}"/spark"
             config = ${system.spark.path.home}"/conf"
             log = ${system.spark.path.home}"/logs"
+            work = ${system.spark.path.home}"/work"
         }
         startup {
             max.attempts = ${system.default.startup.max.attempts}
@@ -28,6 +29,8 @@ system {
                 SPARK_WORKER_CORES = ${system.default.config.parallelism.per-node}
                 SPARK_EXECUTOR_CORES = ${system.default.config.parallelism.per-node}
                 SPARK_EXECUTOR_MEMORY = "512m"
+                # Enables periodic cleanup of worker / application dirs every 5 min. for data older than 1 hour.
+                SPARK_WORKER_OPTS = """"-Dspark.worker.cleanup.enabled=true -Dspark.worker.cleanup.interval=300 -Dspark.worker.cleanup.appDataTtl=3600""""
             }
             # spark-defaults.conf entries
             defaults {

peel-extensions/src/main/resources/templates/spark/conf/spark-env.sh.mustache

@@ -42,7 +42,7 @@
 {{#SPARK_WORKER_WEBUI_PORT}}SPARK_WORKER_WEBUI_PORT={{SPARK_WORKER_WEBUI_PORT}}{{/SPARK_WORKER_WEBUI_PORT}}{{^SPARK_WORKER_WEBUI_PORT}}# - SPARK_WORKER_WEBUI_PORT, to use non-default ports for the worker{{/SPARK_WORKER_WEBUI_PORT}}
 {{#SPARK_WORKER_INSTANCES}}SPARK_WORKER_INSTANCES={{SPARK_WORKER_INSTANCES}}{{/SPARK_WORKER_INSTANCES}}{{^SPARK_WORKER_INSTANCES}}# - SPARK_WORKER_INSTANCES, to set the number of worker processes per node{{/SPARK_WORKER_INSTANCES}}
 {{#SPARK_WORKER_DIR}}SPARK_WORKER_DIR={{SPARK_WORKER_DIR}}{{/SPARK_WORKER_DIR}}{{^SPARK_WORKER_DIR}}# - SPARK_WORKER_DIR, to set the working directory of worker processes{{/SPARK_WORKER_DIR}}
-{{#SPARK_WORKER_OPTS}}SPARK_WORKER_OPTS={{SPARK_WORKER_OPTS}}{{/SPARK_WORKER_OPTS}}{{^SPARK_WORKER_OPTS}}# - SPARK_WORKER_OPTS, to set config properties only for the worker (e.g. "-Dx=y"){{/SPARK_WORKER_OPTS}}
+{{#SPARK_WORKER_OPTS}}SPARK_WORKER_OPTS={{{SPARK_WORKER_OPTS}}}{{/SPARK_WORKER_OPTS}}{{^SPARK_WORKER_OPTS}}# - SPARK_WORKER_OPTS, to set config properties only for the worker (e.g. "-Dx=y"){{/SPARK_WORKER_OPTS}}
 {{#SPARK_HISTORY_OPTS}}SPARK_HISTORY_OPTS={{SPARK_HISTORY_OPTS}}{{/SPARK_HISTORY_OPTS}}{{^SPARK_HISTORY_OPTS}}# - SPARK_HISTORY_OPTS, to set config properties only for the history server (e.g. "-Dx=y"){{/SPARK_HISTORY_OPTS}}
 {{#SPARK_DAEMON_JAVA_OPTS}}SPARK_DAEMON_JAVA_OPTS={{SPARK_DAEMON_JAVA_OPTS}}{{/SPARK_DAEMON_JAVA_OPTS}}{{^SPARK_DAEMON_JAVA_OPTS}}# - SPARK_DAEMON_JAVA_OPTS, to set config properties for all daemons (e.g. "-Dx=y"){{/SPARK_DAEMON_JAVA_OPTS}}
 {{#SPARK_PUBLIC_DNS}}SPARK_PUBLIC_DNS={{SPARK_PUBLIC_DNS}}{{/SPARK_PUBLIC_DNS}}{{^SPARK_PUBLIC_DNS}}# - SPARK_PUBLIC_DNS, to set the public dns name of the master or workers{{/SPARK_PUBLIC_DNS}}

peel-extensions/src/main/scala/org/peelframework/spark/beans/system/Spark.scala

@@ -140,13 +140,27 @@ class Spark(
       s""" ssh $user@$host "$cmd" """
     }
 
+    val rmWorkDir = (host: String, workDir: String) => {
+      val cmd = s""" rm -Rf $workDir/* """
+      s""" ssh $user@$host "$cmd" """
+    }
+
     val hosts = config.getStringList(s"system.$configKey.config.slaves").asScala
     val paths = config.getString(s"system.$configKey.config.defaults.spark.local.dir").split(',')
+    val workDir = config.getString(s"system.$configKey.path.work")
 
-    val futureInitOps = Future.traverse(hosts)(host => Future {
-      logger.info(s"Initializing Spark tmp directories '${paths.mkString(",")}' at $host")
-      shell ! (init(host, paths), s"Unable to initialize Spark tmp directories '${paths.mkString(",")}' at $host.")
-    })
+    val futureInitOps = Future.traverse(hosts){ host =>
+      for {
+        _ <- Future {
+          logger.info(s"Initializing Spark tmp directories '${paths.mkString(",")}' at $host")
+          shell ! (init(host, paths), s"Unable to initialize Spark tmp directories '${paths.mkString(",")}' at $host.")
+        }
+        f <- Future {
+          logger.debug(s"Removing Spark work directory content '$workDir' at $host")
+          shell ! (rmWorkDir(host, workDir), s"Unable to remove Spark work directory content '$workDir' at $host.", fatal = false)
+        }
+      } yield f
+    }
 
     // await for all futureInitOps to finish
     Await.result(futureInitOps, Math.max(30, 5 * hosts.size).seconds)