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GeezerVison is showing github.com — [3.11] gh-96387: take_gil() resets drop request before exit (#96869) by vstinner · Pull Request #96941 · python/cpython

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@vstinner

@vstinner vstinner commented Sep 19, 2022 •
edited by bedevere-bot
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At Python exit, sometimes a thread holding the GIL can wait forever for a thread (usually a daemon thread) which requested to drop the GIL, whereas the thread already exited. To fix the race condition, the thread which requested the GIL drop now resets its request before exiting.

take_gil() now calls RESET_GIL_DROP_REQUEST() before PyThread_exit_thread() if it called SET_GIL_DROP_REQUEST to fix a race condition with drop_gil().

Issue discovered and analyzed by Mingliang ZHAO.

(cherry picked from commit 04f4977)

  • Issue: The main thread hang at drop_gil due to FORCE_SWITCHING after daemon thread exited #96387

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@vstinner
gh-96387: take_gil() resets drop request before exit (#96869)
978a6b4 
At Python exit, sometimes a thread holding the GIL can wait forever
for a thread (usually a daemon thread) which requested to drop the
GIL, whereas the thread already exited. To fix the race condition,
the thread which requested the GIL drop now resets its request before
exiting.

take_gil() now calls RESET_GIL_DROP_REQUEST() before
PyThread_exit_thread() if it called SET_GIL_DROP_REQUEST to fix a
race condition with drop_gil().

Issue discovered and analyzed by Mingliang ZHAO.

(cherry picked from commit 04f4977)
@vstinner vstinner added the needs backport to 3.10 label Sep 19, 2022
@bedevere-bot bedevere-bot added the awaiting core review label Sep 19, 2022
@bedevere-bot bedevere-bot mentioned this pull request Sep 19, 2022
gh-96387: take_gil() resets drop request before exit #96869
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@vstinner
vstinner merged commit 6ff5471 into python:3.11 Sep 20, 2022
@miss-islington

miss-islington commented Sep 20, 2022

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Thanks @vstinner for the PR 🌮🎉.. I'm working now to backport this PR to: 3.10.
🐍🍒⛏🤖
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@bedevere-bot bedevere-bot removed the awaiting core review label Sep 20, 2022
@vstinner
vstinner deleted the take_gil311 branch September 20, 2022 00:12
@bedevere-bot

bedevere-bot commented Sep 20, 2022

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GH-96943 is a backport of this pull request to the 3.10 branch.
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@bedevere-bot bedevere-bot removed the needs backport to 3.10 label Sep 20, 2022
miss-islington pushed a commit to miss-islington/cpython that referenced this pull request Sep 20, 2022
@vstinner @miss-islington
pythongh-96387: take_gil() resets drop request before exit (pythonGH-…
bfb99c8 
…96869) (pythonGH-96941)

At Python exit, sometimes a thread holding the GIL can wait forever
for a thread (usually a daemon thread) which requested to drop the
GIL, whereas the thread already exited. To fix the race condition,
the thread which requested the GIL drop now resets its request before
exiting.

take_gil() now calls RESET_GIL_DROP_REQUEST() before
PyThread_exit_thread() if it called SET_GIL_DROP_REQUEST to fix a
race condition with drop_gil().

Issue discovered and analyzed by Mingliang ZHAO.

(cherry picked from commit 04f4977)
(cherry picked from commit 6ff5471)

Co-authored-by: Victor Stinner <[email protected]>
miss-islington added a commit that referenced this pull request Sep 20, 2022
@miss-islington @vstinner
gh-96387: take_gil() resets drop request before exit (GH-96869) (GH-9…
dcff50a 
…6941)

At Python exit, sometimes a thread holding the GIL can wait forever
for a thread (usually a daemon thread) which requested to drop the
GIL, whereas the thread already exited. To fix the race condition,
the thread which requested the GIL drop now resets its request before
exiting.

take_gil() now calls RESET_GIL_DROP_REQUEST() before
PyThread_exit_thread() if it called SET_GIL_DROP_REQUEST to fix a
race condition with drop_gil().

Issue discovered and analyzed by Mingliang ZHAO.

(cherry picked from commit 04f4977)
(cherry picked from commit 6ff5471)

Co-authored-by: Victor Stinner <[email protected]>
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3 participants

@vstinner @miss-islington @bedevere-bot
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