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[3.12] gh-114440: Close writer pipe in multiprocessing.Queue, not concurrent.futures #114489

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encukou merged 2 commits into from
Jan 24, 2024
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[3.12] gh-114440: Close writer pipe in multiprocessing.Queue, not concurrent.futures #114489

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[3.12] gh-114440: Close writer pipe in multiprocessing.Queue, not con…
encukou Jan 23, 2024
62af0b7
Update Misc/NEWS.d/next/Library/2023-09-25-02-11-14.gh-issue-114440.b…
serhiy-storchaka Jan 23, 2024
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5 changes: 0 additions & 5 deletions Lib/concurrent/futures/process.py
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Original file line number Diff line number Diff line change
Expand Up @@ -524,11 +524,6 @@ def _terminate_broken(self, cause):

self.call_queue._terminate_broken()

# gh-107219: Close the connection writer which can unblock
# Queue._feed() if it was stuck in send_bytes().
if sys.platform == 'win32':
self.call_queue._writer.close()

# clean up resources
self._join_executor_internals(broken=True)

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5 changes: 5 additions & 0 deletions Lib/multiprocessing/queues.py
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Expand Up @@ -164,6 +164,11 @@ def _terminate_broken(self):
# gh-94777: Prevent queue writing to a pipe which is no longer read.
self._reader.close()

# gh-107219: Close the connection writer which can unblock
# Queue._feed() if it was stuck in send_bytes().
if sys.platform == 'win32':
self._writer.close()

self.close()
self.join_thread()

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6 changes: 6 additions & 0 deletions Misc/NEWS.d/next/Library/2023-09-25-02-11-14.gh-issue-114440.b2TrqG.rst
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@@ -0,0 +1,6 @@
On Windows, closing the connection writer when cleaning up a broken
:cls:`multiprocessing.Queue` queue is now done for all queues, rather than
only in :mod:`concurrent.futures` manager thread.
This can prevent a deadlock when a ``multiprocessing`` worker process terminates
without cleaning up.
This completes the backport of patches by Victor Stinner and Serhiy Storchaka.