GeezerVison is showing github.com — IsolatedAsyncioTestCase and asyncio.run no-longer call asyncio.set_event_loop · Issue #93896 · python/cpython
IsolatedAsyncioTestCase and asyncio.run no-longer call asyncio.set_event_loop #93896Activitygraingert commented on Jun 16, 2022 ContributorAuthor More actions import sys
import asyncio
async def run_subprocess():
proc = await asyncio.create_subprocess_shell(
"exit 0",
stdin=asyncio.subprocess.DEVNULL,
stdout=asyncio.subprocess.DEVNULL,
stderr=asyncio.subprocess.DEVNULL,
)
await proc.wait()
print("success!")
async def amain():
await asyncio.to_thread(asyncio.run, run_subprocess())
def main():
asyncio.get_event_loop_policy().set_child_watcher(asyncio.SafeChildWatcher())
asyncio.run(amain())
if __name__ == "__main__":
sys.exit(main()) graingert@superjacent ~/projects python3.10 demo_subprocess.py
success!
graingert@superjacent ~/projects python3.11 demo_subprocess.py
Traceback (most recent call last):
File "/home/graingert/projects/demo_subprocess.py", line 26, in <module>
sys.exit(main())
^^^^^^
File "/home/graingert/projects/demo_subprocess.py", line 22, in main
asyncio.run(amain())
^^^^^^^^^^^^^^^^^^^^
File "/usr/lib/python3.11/asyncio/runners.py", line 181, in run
return runner.run(main)
^^^^^^^^^^^^^^^^
File "/usr/lib/python3.11/asyncio/runners.py", line 115, in run
return self._loop.run_until_complete(task)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/lib/python3.11/asyncio/base_events.py", line 650, in run_until_complete
return future.result()
^^^^^^^^^^^^^^^
File "/home/graingert/projects/demo_subprocess.py", line 17, in amain
await asyncio.to_thread(asyncio.run, run_subprocess())
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/lib/python3.11/asyncio/threads.py", line 25, in to_thread
return await loop.run_in_executor(None, func_call)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/lib/python3.11/concurrent/futures/thread.py", line 58, in run
result = self.fn(*self.args, **self.kwargs)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/lib/python3.11/asyncio/runners.py", line 181, in run
return runner.run(main)
^^^^^^^^^^^^^^^^
File "/usr/lib/python3.11/asyncio/runners.py", line 115, in run
return self._loop.run_until_complete(task)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/lib/python3.11/asyncio/base_events.py", line 650, in run_until_complete
return future.result()
^^^^^^^^^^^^^^^
File "/home/graingert/projects/demo_subprocess.py", line 6, in run_subprocess
proc = await asyncio.create_subprocess_shell(
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/lib/python3.11/asyncio/subprocess.py", line 205, in create_subprocess_shell
transport, protocol = await loop.subprocess_shell(
^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/lib/python3.11/asyncio/base_events.py", line 1647, in subprocess_shell
transport = await self._make_subprocess_transport(
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/lib/python3.11/asyncio/unix_events.py", line 204, in _make_subprocess_transport
raise RuntimeError("asyncio.get_child_watcher() is not activated, "
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
RuntimeError: asyncio.get_child_watcher() is not activated, subprocess support is not installed.
graingert commented on Jun 16, 2022 ContributorAuthor More actions I know there were some efforts to deprecate get/set_event_loop_policy and child watchers #82772 so I think those Deprecations should be applied before asyncio.run/IsolatedAsyncioTestCase stops calling asyncio.set_event_loop() graingert commented on Jun 17, 2022 ContributorAuthor More actions alternatively is there still time to deprecate the child watchers system and the policy system in favor of
asyncio.Runner(loop_factory=asyncio.ProactorEventLoop/asyncio.SelectorEventLoop/uvloop.uvloop.new_event_loop) before the 3.11 release?
that would be deprecating:
asyncio.get_event_loop() # already deprecated unless the loop is running
asyncio.set_event_loop() # asyncio.set_event_loop(None) should probably be exempt
asyncio.get_event_loop_policy()
asyncio.set_event_loop_policy() # asyncio.set_event_loop_policy(None) should probably be exempt
asyncio.set_child_watcher()
asyncio.get_child_watcher() will remain and will always be asyncio.PidfdChildWatcher on old kernels and asyncio.ThreadedChildWatcher on very old kernels
asyncio.new_event_loop() will issue a DeprecationWarning if the current policy is not the default policy, and then become an alias of
if sys.platform == "win32":
new_event_loop = ProactorEventLoop
else:
new_event_loop = SelectorEventLoop
graingert commented on Jun 23, 2022 ContributorAuthor More actions this is also broken with the PidfdChildWatcher encukou commented on Jun 27, 2022 Marking as potential release blocker. graingert commented on Jun 30, 2022 ContributorAuthor More actions gvanrossum commented on Jul 6, 2022 Go ahead with that PR, Kumar. kumaraditya303 commented on Jul 6, 2022 I created #94593 which fixes this by reverting to the 3.10 and earlier behavior of setting the event loop if no loop factory was supplied. No new parameter is added so can be backport to 3.11. graingert commented on Jul 6, 2022 ContributorAuthor More actions
We should have a separate discussion about the future of the policy system.
see #94597 added a commit that references this issue on Jul 6, 2022GH-93896: AAlways set event loop in asyncio.run and IsolatedAsyncioTe… added 2 commits that reference this issue on Jul 6, 2022pythonGH-93896: AAlways set event loop in asyncio.run and IsolatedAsy… GH-93896: AAlways set event loop in asyncio.run and IsolatedAsyncioTe… kumaraditya303 commented on Jul 6, 2022 This is fixed in 3.12 (main) and 3.11 by #94593 #94608 respectively.
Thanks everyone! ixenion commented on Apr 24, 2024 gvanrossum commented on Apr 24, 2024 @ixenion Please be civil. This is not the place to get help, but you can find help for Python issues on discuss.python.org. locked as off topic and limited conversation to collaborators on Apr 24, 2024
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