diff options
| -rw-r--r-- | Lib/concurrent/futures/thread.py | 6 | ||||
| -rw-r--r-- | Lib/test/test_concurrent_futures.py | 14 | ||||
| -rw-r--r-- | Misc/NEWS.d/next/Library/2021-08-28-13-00-12.bpo-45021.rReeaj.rst | 1 |
3 files changed, 21 insertions, 0 deletions
diff --git a/Lib/concurrent/futures/thread.py b/Lib/concurrent/futures/thread.py index b7a2cac..51c942f 100644 --- a/Lib/concurrent/futures/thread.py +++ b/Lib/concurrent/futures/thread.py @@ -36,6 +36,12 @@ def _python_exit(): # See bpo-39812 for context. threading._register_atexit(_python_exit) +# At fork, reinitialize the `_global_shutdown_lock` lock in the child process +if hasattr(os, 'register_at_fork'): + os.register_at_fork(before=_global_shutdown_lock.acquire, + after_in_child=_global_shutdown_lock._at_fork_reinit, + after_in_parent=_global_shutdown_lock.release) + class _WorkItem(object): def __init__(self, future, fn, args, kwargs): diff --git a/Lib/test/test_concurrent_futures.py b/Lib/test/test_concurrent_futures.py index b0df12c..84209ca 100644 --- a/Lib/test/test_concurrent_futures.py +++ b/Lib/test/test_concurrent_futures.py @@ -911,6 +911,20 @@ class ThreadPoolExecutorTest(ThreadPoolMixin, ExecutorTest, BaseTestCase): self.assertEqual(len(executor._threads), 1) executor.shutdown(wait=True) + @unittest.skipUnless(hasattr(os, 'register_at_fork'), 'need os.register_at_fork') + def test_hang_global_shutdown_lock(self): + # bpo-45021: _global_shutdown_lock should be reinitialized in the child + # process, otherwise it will never exit + def submit(pool): + pool.submit(submit, pool) + + with futures.ThreadPoolExecutor(1) as pool: + pool.submit(submit, pool) + + for _ in range(50): + with futures.ProcessPoolExecutor(1, mp_context=get_context('fork')) as workers: + workers.submit(tuple) + class ProcessPoolExecutorTest(ExecutorTest): diff --git a/Misc/NEWS.d/next/Library/2021-08-28-13-00-12.bpo-45021.rReeaj.rst b/Misc/NEWS.d/next/Library/2021-08-28-13-00-12.bpo-45021.rReeaj.rst new file mode 100644 index 0000000..54fd910 --- /dev/null +++ b/Misc/NEWS.d/next/Library/2021-08-28-13-00-12.bpo-45021.rReeaj.rst @@ -0,0 +1 @@ +Fix a potential deadlock at shutdown of forked children when using :mod:`concurrent.futures` module
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