bpo-39877: take_gil() now exits the thread if finalizing by vstinner · Pull Request #18854 · python/cpython
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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.
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.
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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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| MUTEX_UNLOCK(gil->mutex); | ||
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| if (thread_must_exit(tstate)) { |
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I'm not sure why you're doing this here. It doesn't seem necessary and, furthermore, it's unlikely to trigger.
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| { | ||
| int err = errno; | ||
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| if (thread_must_exit(tstate)) { |
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Ok, but shouldn't you do this after COND_TIMED_WAIT below as well?
When you're done making the requested changes, leave the comment: I have made the requested changes; please review again.
| to run after wait_for_thread_shutdown() and before Py_Finalize() | ||
| completes. For example, when _PyImport_Cleanup() executes Python | ||
| code. */ | ||
| MUTEX_UNLOCK(gil->mutex); |
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I'm not sure if anyone else should be done here.
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For example, is COND_SIGNAL(gil->cond) needed to wake up the next thread waiting on COND_TIMED_WAIT()?
I have made the requested changes; please review again.
Thanks for making the requested changes!
@pitrou: please review the changes made to this pull request.
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.