GeezerVison is showing github.com — 3.11.5 regression: StreamWriter.__del__ fails if event loop is already closed · Issue #109538 · python/cpython
3.11.5 regression: StreamWriter.__del__ fails if event loop is already closed #109538DescriptionBug report
Bug description:
PR #107650 added a StreamWriter.__del__ that emits a ResourceWarning if a StreamWriter is not closed by the time it is garbage collected, and it has been backported as 3.11.5. However, if the event loop has already been closed by the time this happens, it causes a RuntimeError message to be displayed. It's non-fatal because exceptions raised by __del__ are ignored, but it causes an error message to be displayed to the user (as opposed to ResourceWarning, which is only shown when one opts in).
Code like the following used to run without any visible error, but now prints a traceback (and does not report the ResourceWarning for the unclosed StreamWriter when run with -X dev):
#!/usr/bin/env python3
import asyncio
async def main():
global writer
reader, writer = await asyncio.open_connection("127.0.0.1", 22)
asyncio.run(main())Output in 3.11.5:
Exception ignored in: <function StreamWriter.__del__ at 0x7fd54ee11080>
Traceback (most recent call last):
File "/usr/lib/python3.11/asyncio/streams.py", line 396, in __del__
File "/usr/lib/python3.11/asyncio/streams.py", line 344, in close
File "/usr/lib/python3.11/asyncio/selector_events.py", line 860, in close
File "/usr/lib/python3.11/asyncio/base_events.py", line 761, in call_soon
File "/usr/lib/python3.11/asyncio/base_events.py", line 519, in _check_closed
RuntimeError: Event loop is closed
CPython versions tested on:
3.11
Operating systems tested on:
Linux
Linked PRs
Reacted by sunilgoothy, NicholasTNG, sphr2k, Michael, Bekzod Mirahmedov, Zach Probst, Peter F. Patel-Schneider, Klemens Karaś, Oleksandr, Michael Czigler and 8 more Activitydpr-0 commented on Sep 27, 2023 smirnoffs commented on Oct 6, 2023 I have the same problem with 3.11.6. Thanks for reporting it. pfps commented on Oct 25, 2023 dpr-0 commented on Oct 26, 2023
Is there a workaround?
Use gc.collect() may help
Here is my workaround.
@pytest.fixture
def event_loop():
policy = asyncio.get_event_loop_policy()
loop = policy.new_event_loop()
loop.set_debug(True)
yield loop
gc.collect()
loop.close()pfps commented on Oct 26, 2023 @dpr-0 Thanks, but just adding that to my program didn't prevent the messages. dpr-0 commented on Oct 26, 2023
@dpr-0 Thanks, but just adding that to my program didn't prevent the messages.
Hope you can find the problem T^T dtatarkin commented on Nov 9, 2023 Same problem for python 3.12.0 Reacted by anton-m-py and Eduardo gvanrossum commented on Nov 9, 2023 Sorry for the inconvenience. Can you (or anyone else reading this) submit a PR for the main branch? We will then backport the PR to 3.12 and 3.11. bmerry commented on Nov 10, 2023 ContributorAuthor More actions
Sorry for the inconvenience. Can you (or anyone else reading this) submit a PR for the main branch? We will then backport the PR to 3.12 and 3.11.
What is the desired behaviour if the event loop is already closed when the StreamWriter is destroyed? Should __del__ just become a no-op? RoTorEx commented on Nov 22, 2023 Did anyone find a solution? gvanrossum commented on Nov 22, 2023
Did anyone find a solution?
It's fixed in the main, 3.12 and 3.11 branches. It will be fixed in the next official releases of 3.11 and 3.12 from python.org (within 1-2 months). Reacted by Andrei, DPR, Aleksey, Dmitriy Tatarkin, Markus, shaliamekh-innowise and Rajesh Kumar Nallabanda LostInDarkMath commented on Jan 23, 2024
Did anyone find a solution?
It's fixed in the main, 3.12 and 3.11 branches. It will be fixed in the next official releases of 3.11 and 3.12 from python.org (within 1-2 months).
Is this fix included in 3.11.7?
Because I'm still able to reproduce it with Python 3.11.7
Edit: nevermind, I used 3.11.6 by accident. All good mdczaplicki commented on May 15, 2024 Just so you know, on python 3.11.9 with this setting for pytest:
[tool.pytest.ini_options]
asyncio_mode = "auto"
filterwarnings = ["error"]
the suite still raises an error from ignored warning:
def _warn_teardown_exception(
hook_name: str, hook_impl: HookImpl, e: BaseException
) -> None:
msg = "A plugin raised an exception during an old-style hookwrapper teardown.\n"
msg += f"Plugin: {hook_impl.plugin_name}, Hook: {hook_name}\n"
msg += f"{type(e).__name__}: {e}\n"
msg += "For more information see https://pluggy.readthedocs.io/en/stable/api_reference.html#pluggy.PluggyTeardownRaisedWarning" # noqa: E501
> warnings.warn(PluggyTeardownRaisedWarning(msg), stacklevel=5)
E pluggy.PluggyTeardownRaisedWarning: A plugin raised an exception during an old-style hookwrapper teardown.
E Plugin: unraisableexception, Hook: pytest_runtest_setup
E PytestUnraisableExceptionWarning: Exception ignored in: <function StreamWriter.__del__ at 0xffffb9f4d620>
E
E Traceback (most recent call last):
E File "/usr/local/lib/python3.11/asyncio/streams.py", line 411, in __del__
E warnings.warn("loop is closed", ResourceWarning)
E ResourceWarning: loop is closed
E
E For more information see https://pluggy.readthedocs.io/en/stable/api_reference.html#pluggy.PluggyTeardownRaisedWarning
../virtualenvs/project-bTydf30B-py3.11/lib/python3.11/site-packages/pluggy/_callers.py:50: PluggyTeardownRaisedWarning
def unraisable_exception_runtest_hook() -> Generator[None, None, None]:
with catch_unraisable_exception() as cm:
yield
if cm.unraisable:
if cm.unraisable.err_msg is not None:
err_msg = cm.unraisable.err_msg
else:
err_msg = "Exception ignored in"
msg = f"{err_msg}: {cm.unraisable.object!r}\n\n"
msg += "".join(
traceback.format_exception(
cm.unraisable.exc_type,
cm.unraisable.exc_value,
cm.unraisable.exc_traceback,
)
)
> warnings.warn(pytest.PytestUnraisableExceptionWarning(msg))
E pytest.PytestUnraisableExceptionWarning: Exception ignored in: <function StreamWriter.__del__ at 0xffff878ed620>
E
E Traceback (most recent call last):
E File "/usr/local/lib/python3.11/asyncio/streams.py", line 411, in __del__
E warnings.warn("loop is closed", ResourceWarning)
E ResourceWarning: loop is closed
../virtualenvs/project-bTydf30B-py3.11/lib/python3.11/site-packages/_pytest/unraisableexception.py:78: PytestUnraisableExceptionWarning
Is it expected? Should I add those warnings as ignored to my pytest setup? gvanrossum commented on May 16, 2024 @mdczaplicki That error might be due to pytest -- I cannot tell from the output you're posting. If you really think this is still not fixed in CPython 3.11.9, can you open a new issue with complete instructions for reproducing the problem? (Ideally also testing in 3.12.)
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