Maintenance updates (#1081)

ipykernel/eventloops.py

@@ -9,6 +9,7 @@
 from functools import partial
 
 import zmq
+from jupyter_core.utils import run_sync
 from packaging.version import Version as V  # noqa
 from traitlets.config.application import Application
 
@@ -250,12 +251,6 @@ def process_stream_events(stream, *a, **kw):
         app.mainloop()
 
     else:
-        import asyncio
-
-        import nest_asyncio
-
-        nest_asyncio.apply()
-
         doi = kernel.do_one_iteration
         # Tk uses milliseconds
         poll_interval = int(1000 * kernel._poll_interval)
@@ -267,9 +262,8 @@ def __init__(self, app, func):
                 self.func = func
 
             def on_timer(self):
-                loop = asyncio.get_event_loop()
                 try:
-                    loop.run_until_complete(self.func())
+                    run_sync(self.func)()
                 except Exception:
                     kernel.log.exception("Error in message handler")
                 self.app.after(poll_interval, self.on_timer)

ipykernel/inprocess/client.py

@@ -15,11 +15,7 @@
 
 from jupyter_client.client import KernelClient
 from jupyter_client.clientabc import KernelClientABC
-
-try:
-    from jupyter_client.utils import run_sync  # requires 7.0+
-except ImportError:
-    run_sync = None  # type:ignore
+from jupyter_core.utils import run_sync
 
 # IPython imports
 from traitlets import Instance, Type, default

ipykernel/kernelapp.py

@@ -13,6 +13,7 @@
 from functools import partial
 from io import FileIO, TextIOWrapper
 from logging import StreamHandler
+from typing import Optional
 
 import zmq
 from IPython.core.application import (  # type:ignore[attr-defined]
@@ -131,7 +132,7 @@ class IPKernelApp(BaseIPythonApplication, InteractiveShellApp, ConnectionFileMix
     poller = Any()  # don't restrict this even though current pollers are all Threads
     heartbeat = Instance(Heartbeat, allow_none=True)
 
-    context = Any()
+    context: Optional[zmq.Context] = Any()  # type:ignore[assignment]
     shell_socket = Any()
     control_socket = Any()
     debugpy_socket = Any()
@@ -403,7 +404,8 @@ def close(self):
             if socket and not socket.closed:
                 socket.close()
         self.log.debug("Terminating zmq context")
-        self.context.term()
+        if self.context:
+            self.context.term()
         self.log.debug("Terminated zmq context")
 
     def log_connection_info(self):

pyproject.toml

@@ -30,12 +30,12 @@ dependencies = [
     "comm>=0.1.1",
     "traitlets>=5.4.0",
     "jupyter_client>=6.1.12",
+    "jupyter_core>=4.12,!=5.0.*",
     "tornado>=6.1",
     "matplotlib-inline>=0.1",
     'appnope;platform_system=="Darwin"',
     "pyzmq>=17",
     "psutil",
-    "nest_asyncio",
     "packaging",
 ]