gh-125451: Fix deadlock in ProcessPoolExecutor shutdown #125492
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There was a deadlock when `ProcessPoolExecutor` shuts down at the same time that a queueing thread handles an error when processing a task. Don't use `_shutdown_lock` to protect the `_ThreadWakeup` pipes -- use an internal lock instead. This fixes the ordering deadlock where the `ExecutorManagerThread` holds the `_shutdown_lock` and joins the queueing thread, while the queueing thread is attempting to acquire the `_shutdown_lock` while closing the `_ThreadWakeup`.
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needs backport to 3.13
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Near line 724, please remove the comment:
# _shutdown_lock must be locked to access _ThreadWakeup (...)
Oh, I made commit a4dfe8e in 2020 to fix another race condition:
commit a4dfe8ede5a37576e17035dccfe109ba7752237e
Author: Victor Stinner <vstinner@python.org>
Date: Wed Apr 29 03:32:06 2020 +0200
bpo-39995: Fix concurrent.futures _ThreadWakeup (GH-19760)
Fix a race condition in concurrent.futures._ThreadWakeup: access to
_ThreadWakeup is now protected with the shutdown lock.
The failure of these 2 workers is known: #125535 |
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!buildbot AMD64 Fedora Stable Refleaks |
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🤖 New build scheduled with the buildbot fleet by @colesbury for commit 84db201 🤖 The command will test the builders whose names match following regular expression: The builders matched are:
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kumaraditya303
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Oct 16, 2024
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Thanks @colesbury for the PR 🌮🎉.. I'm working now to backport this PR to: 3.12, 3.13. |
miss-islington
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…GH-125492) There was a deadlock when `ProcessPoolExecutor` shuts down at the same time that a queueing thread handles an error processing a task. Don't use `_shutdown_lock` to protect the `_ThreadWakeup` pipes -- use an internal lock instead. This fixes the ordering deadlock where the `ExecutorManagerThread` holds the `_shutdown_lock` and joins the queueing thread, while the queueing thread is attempting to acquire the `_shutdown_lock` while closing the `_ThreadWakeup`. (cherry picked from commit 760872e) Co-authored-by: Sam Gross <colesbury@gmail.com>
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Sorry, @colesbury, I could not cleanly backport this to |
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GH-125598 is a backport of this pull request to the 3.13 branch. |
colesbury
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…ythonGH-125492) There was a deadlock when `ProcessPoolExecutor` shuts down at the same time that a queueing thread handles an error processing a task. Don't use `_shutdown_lock` to protect the `_ThreadWakeup` pipes -- use an internal lock instead. This fixes the ordering deadlock where the `ExecutorManagerThread` holds the `_shutdown_lock` and joins the queueing thread, while the queueing thread is attempting to acquire the `_shutdown_lock` while closing the `_ThreadWakeup`. (cherry picked from commit 760872e) Co-authored-by: Sam Gross <colesbury@gmail.com>
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GH-125599 is a backport of this pull request to the 3.12 branch. |
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…5492) (GH-125598) There was a deadlock when `ProcessPoolExecutor` shuts down at the same time that a queueing thread handles an error processing a task. Don't use `_shutdown_lock` to protect the `_ThreadWakeup` pipes -- use an internal lock instead. This fixes the ordering deadlock where the `ExecutorManagerThread` holds the `_shutdown_lock` and joins the queueing thread, while the queueing thread is attempting to acquire the `_shutdown_lock` while closing the `_ThreadWakeup`. (cherry picked from commit 760872e) Co-authored-by: Sam Gross <colesbury@gmail.com>
colesbury
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…5492) (#125599) There was a deadlock when `ProcessPoolExecutor` shuts down at the same time that a queueing thread handles an error processing a task. Don't use `_shutdown_lock` to protect the `_ThreadWakeup` pipes -- use an internal lock instead. This fixes the ordering deadlock where the `ExecutorManagerThread` holds the `_shutdown_lock` and joins the queueing thread, while the queueing thread is attempting to acquire the `_shutdown_lock` while closing the `_ThreadWakeup`. (cherry picked from commit 760872e)
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There was a deadlock when
ProcessPoolExecutorshuts down at the same time that a queueing thread handles an error when processing a task. Don't use_shutdown_lockto protect the_ThreadWakeuppipes -- use an internal lock instead. This fixes the ordering deadlock where theExecutorManagerThreadholds the_shutdown_lockand joins the queueing thread, while the queueing thread is attempting to acquire the_shutdown_lockwhile closing the_ThreadWakeup.