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bpo-39877: take_gil() now exits the thread if finalizing#18854

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vstinner wants to merge 2 commits into
python:masterfrom
vstinner:take_gil_exit
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bpo-39877: take_gil() now exits the thread if finalizing#18854
vstinner wants to merge 2 commits into
python:masterfrom
vstinner:take_gil_exit

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@vstinner

@vstinner vstinner commented Mar 8, 2020 •
edited by bedevere-bot
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take_gil() is now responsible to exit the thread if Python is
finalizing. Not only exit before trying to acquire the GIL, but exit
also once the GIL is succesfully acquired.

https://bugs.python.org/issue39877

@vstinner
bpo-39877: take_gil() now exits the thread if finalizing …
9ac0b25 
take_gil() is now responsible to exit the thread if Python is
finalizing. Not only exit before trying to acquire the GIL, but exit
also once the GIL is succesfully acquired.
@vstinner

vstinner commented Mar 8, 2020

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@pitrou: My previous change introduced a race condition: https://bugs.python.org/issue39877#msg363667 This change should fix it.

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vstinner commented Mar 8, 2020 •
edited by bedevere-bot
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I tested manually: with this change and PR #18848, asyncio_gc.py of bpo-19466 does no longer crash.

pitrou
pitrou requested changes Mar 8, 2020
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I believe the fix is somehow incomplete, see below.
Also, as you say, the problem is "is it safe to destroy the GIL if there are still daemon threads trying to take it?".

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bedevere-bot commented Mar 8, 2020

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When you're done making the requested changes, leave the comment: I have made the requested changes; please review again.

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vstinner commented Mar 9, 2020

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I have made the requested changes; please review again.

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bedevere-bot commented Mar 9, 2020

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Thanks for making the requested changes!

@pitrou: please review the changes made to this pull request.

@bedevere-bot bedevere-bot requested a review from pitrou March 9, 2020 07:44
@vstinner vstinner mentioned this pull request Mar 9, 2020
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vstinner commented Mar 9, 2020

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I merged PR #18890 which checks if the thread must exit at function exit as well. In short, it restores the Python 3.8 behavior.

I close this PR for now.

We can revisit take_gil() later to try to adjust/optimize it later. I prefer to move step by step.

@vstinner vstinner closed this Mar 9, 2020
@vstinner vstinner deleted the take_gil_exit branch March 9, 2020 22:13
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