diff options
| -rw-r--r-- | Lib/concurrent/futures/process.py | 5 | ||||
| -rw-r--r-- | Lib/test/test_concurrent_futures.py | 28 | ||||
| -rw-r--r-- | Misc/ACKS | 1 | ||||
| -rw-r--r-- | Misc/NEWS.d/next/Library/2022-06-30-21-28-41.gh-issue-94440.LtgX0d.rst | 2 |
4 files changed, 36 insertions, 0 deletions
diff --git a/Lib/concurrent/futures/process.py b/Lib/concurrent/futures/process.py index 3a8637b..816edab 100644 --- a/Lib/concurrent/futures/process.py +++ b/Lib/concurrent/futures/process.py @@ -366,6 +366,11 @@ class _ExecutorManagerThread(threading.Thread): if self.is_shutting_down(): self.flag_executor_shutting_down() + # When only canceled futures remain in pending_work_items, our + # next call to wait_result_broken_or_wakeup would hang forever. + # This makes sure we have some running futures or none at all. + self.add_call_item_to_queue() + # Since no new work items can be added, it is safe to shutdown # this thread if there are no pending work items. if not self.pending_work_items: diff --git a/Lib/test/test_concurrent_futures.py b/Lib/test/test_concurrent_futures.py index b3520ae..a20cb84 100644 --- a/Lib/test/test_concurrent_futures.py +++ b/Lib/test/test_concurrent_futures.py @@ -14,6 +14,7 @@ import logging from logging.handlers import QueueHandler import os import queue +import signal import sys import threading import time @@ -397,6 +398,33 @@ class ExecutorShutdownTest: self.assertFalse(err) self.assertEqual(out.strip(), b"apple") + def test_hang_gh94440(self): + """shutdown(wait=True) doesn't hang when a future was submitted and + quickly canceled right before shutdown. + + See https://github.com/python/cpython/issues/94440. + """ + if not hasattr(signal, 'alarm'): + raise unittest.SkipTest( + "Tested platform does not support the alarm signal") + + def timeout(_signum, _frame): + raise RuntimeError("timed out waiting for shutdown") + + kwargs = {} + if getattr(self, 'ctx', None): + kwargs['mp_context'] = self.get_context() + executor = self.executor_type(max_workers=1, **kwargs) + executor.submit(int).result() + old_handler = signal.signal(signal.SIGALRM, timeout) + try: + signal.alarm(5) + executor.submit(int).cancel() + executor.shutdown(wait=True) + finally: + signal.alarm(0) + signal.signal(signal.SIGALRM, old_handler) + class ThreadPoolShutdownTest(ThreadPoolMixin, ExecutorShutdownTest, BaseTestCase): def test_threads_terminate(self): @@ -1385,6 +1385,7 @@ Thomas Perl Mathieu Perreault Mark Perrego Trevor Perrin +Yonatan Perry Gabriel de Perthuis Tim Peters Benjamin Peterson diff --git a/Misc/NEWS.d/next/Library/2022-06-30-21-28-41.gh-issue-94440.LtgX0d.rst b/Misc/NEWS.d/next/Library/2022-06-30-21-28-41.gh-issue-94440.LtgX0d.rst new file mode 100644 index 0000000..3eee82e --- /dev/null +++ b/Misc/NEWS.d/next/Library/2022-06-30-21-28-41.gh-issue-94440.LtgX0d.rst @@ -0,0 +1,2 @@ +Fix a :mod:`concurrent.futures.process` bug where ``ProcessPoolExecutor`` shutdown +could hang after a future has been quickly submitted and canceled. |