diff --git a/Lib/concurrent/futures/thread.py b/Lib/concurrent/futures/thread.py index 75d05a76be3f41..5e4904fe300d7d 100644 --- a/Lib/concurrent/futures/thread.py +++ b/Lib/concurrent/futures/thread.py @@ -29,10 +29,14 @@ _threads_queues = weakref.WeakKeyDictionary() _shutdown = False +# Lock that ensures that new workers are not created while the interpreter is +# shutting down. Must be held while mutating _threads_queues and _shutdown. +_global_shutdown_lock = threading.Lock() def _python_exit(): global _shutdown - _shutdown = True + with _global_shutdown_lock: + _shutdown = True items = list(_threads_queues.items()) for t, q in items: q.put(None) @@ -156,7 +160,7 @@ def __init__(self, max_workers=None, thread_name_prefix='', self._initargs = initargs def submit(self, fn, /, *args, **kwargs): - with self._shutdown_lock: + with self._shutdown_lock, _global_shutdown_lock: if self._broken: raise BrokenThreadPool(self._broken) diff --git a/Misc/NEWS.d/next/Library/2019-05-07-19-25-55.bpo-31783.lgLo69.rst b/Misc/NEWS.d/next/Library/2019-05-07-19-25-55.bpo-31783.lgLo69.rst new file mode 100644 index 00000000000000..a261e59ccfecd8 --- /dev/null +++ b/Misc/NEWS.d/next/Library/2019-05-07-19-25-55.bpo-31783.lgLo69.rst @@ -0,0 +1 @@ +Fix race condition in ThreadPoolExecutor when worker threads are created during interpreter shutdown. \ No newline at end of file