don't patch jupyter_client.session at import time

ipyparallel/apps/baseapp.py

@@ -17,6 +17,8 @@
 from traitlets import Bool, Instance, Unicode, default, observe
 from traitlets.config.application import LevelFormatter, catch_config_error
 
+from ipyparallel import util
+
 from .._version import __version__
 
 # FIXME: CUnicode is needed for cli parsing
@@ -136,6 +138,7 @@ def _default_session(self):
     @catch_config_error
     def initialize(self, argv=None):
         """initialize the app"""
+        util._disable_session_extract_dates()
         self.init_config_from_env()
         super().initialize(argv)
         self.init_deprecated_config()

ipyparallel/client/client.py

@@ -570,6 +570,7 @@ def __init__(
             )
             raise ValueError(msg.format(exc.message))
 
+        util._disable_session_extract_dates()
         self.session = Session(**extra_args)
 
         self._query_socket = self._context.socket(zmq.DEALER)

ipyparallel/controller/heartmonitor.py

@@ -18,6 +18,7 @@
 from zmq.devices import ThreadDevice, ThreadMonitoredQueue
 from zmq.eventloop.zmqstream import ZMQStream
 
+from ipyparallel import util
 from ipyparallel.util import bind, connect, log_errors, set_hwm
 
 
@@ -120,6 +121,7 @@ class HeartMonitor(LoggingConfigurable):
 
     @default("session")
     def _default_session(self):
+        util._disable_session_extract_dates()
         return Session(parent=self)
 
     loop = Instance(ioloop.IOLoop)

ipyparallel/controller/scheduler.py

@@ -46,6 +46,7 @@ def _default_loop(self):
 
     @default("session")
     def _default_session(self):
+        util._disable_session_extract_dates()
         return jupyter_client.session.Session(parent=self)
 
     client_stream = Instance(

ipyparallel/engine/app.py

@@ -37,6 +37,7 @@
 from traitlets.config import Config
 from zmq.eventloop import zmqstream
 
+from ipyparallel import util
 from ipyparallel.apps.baseapp import (
     BaseParallelApplication,
     base_aliases,
@@ -405,6 +406,7 @@ def load_connection_file(self):
 
         config.Session.packer = d['pack']
         config.Session.unpacker = d['unpack']
+        util._disable_session_extract_dates()
         self.session = Session(parent=self)
 
         self.log.debug("Config changed:")

ipyparallel/engine/nanny.py

@@ -68,6 +68,7 @@ def __init__(
         self.curve_secretkey = curve_secretkey
         self.config = config
         self.pipe = pipe
+        util._disable_session_extract_dates()
         self.session = Session(config=self.config)
 
         self.log = local_logger(f"{self.__class__.__name__}.{engine_id}", log_level)

ipyparallel/tests/test_db.py

@@ -21,6 +21,7 @@
 
 class TaskDBTest:
     def setUp(self):
+        util._disable_session_extract_dates()
         self.session = Session()
         self.db = self.create_db()
         self.load_records(16)

ipyparallel/util.py

@@ -24,6 +24,7 @@
 from IPython import get_ipython
 from IPython.core.profiledir import ProfileDir, ProfileDirError
 from IPython.paths import get_ipython_dir
+from jupyter_client import session
 from jupyter_client.localinterfaces import is_public_ip, localhost, public_ips
 from tornado.ioloop import IOLoop
 from traitlets.log import get_logger
@@ -599,21 +600,13 @@ def _v(version_s):
     return tuple(int(s) for s in re.findall(r"\d+", version_s))
 
 
-def _patch_jupyter_client_dates():
-    """Monkeypatch jupyter_client.extract_dates to be nondestructive wrt timezone info"""
-    import jupyter_client
-
-    if _v(jupyter_client.__version__) < _v('5.0'):
-        from jupyter_client import session
-
-        if hasattr(session, '_save_extract_dates'):
-            return
-        session._save_extract_dates = session.extract_dates
-        session.extract_dates = extract_dates
-
+@lru_cache()
+def _disable_session_extract_dates():
+    """Monkeypatch jupyter_client.extract_dates to be a no-op
 
-# FIXME: remove patch when we require jupyter_client 5.0
-_patch_jupyter_client_dates()
+    avoids performance problem parsing unused timestamp strings
+    """
+    session.extract_dates = lambda obj: obj
 
 
 def progress(*args, widget=None, **kwargs):

pyproject.toml

@@ -41,7 +41,7 @@ dependencies = [
     "pyzmq>=18",
     "traitlets>=4.3",
     "ipython>=4",
-    "jupyter_client",
+    "jupyter_client>=5",
     "ipykernel>=4.4",
     "tornado>=5.1",
     "psutil",