mirror of https://github.com/python/cpython
bpo-45021: Fix a hang in forked children (GH-28007)
_global_shutdown_lock should be reinitialized in forked children
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@ -36,6 +36,12 @@ def _python_exit():
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# See bpo-39812 for context.
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threading._register_atexit(_python_exit)
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# At fork, reinitialize the `_global_shutdown_lock` lock in the child process
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if hasattr(os, 'register_at_fork'):
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os.register_at_fork(before=_global_shutdown_lock.acquire,
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after_in_child=_global_shutdown_lock._at_fork_reinit,
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after_in_parent=_global_shutdown_lock.release)
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class _WorkItem(object):
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def __init__(self, future, fn, args, kwargs):
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@ -911,6 +911,20 @@ class ThreadPoolExecutorTest(ThreadPoolMixin, ExecutorTest, BaseTestCase):
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self.assertEqual(len(executor._threads), 1)
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executor.shutdown(wait=True)
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@unittest.skipUnless(hasattr(os, 'register_at_fork'), 'need os.register_at_fork')
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def test_hang_global_shutdown_lock(self):
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# bpo-45021: _global_shutdown_lock should be reinitialized in the child
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# process, otherwise it will never exit
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def submit(pool):
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pool.submit(submit, pool)
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with futures.ThreadPoolExecutor(1) as pool:
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pool.submit(submit, pool)
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for _ in range(50):
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with futures.ProcessPoolExecutor(1, mp_context=get_context('fork')) as workers:
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workers.submit(tuple)
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class ProcessPoolExecutorTest(ExecutorTest):
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@ -0,0 +1 @@
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Fix a potential deadlock at shutdown of forked children when using :mod:`concurrent.futures` module
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