STINNER Victor <vstinner at python.org> added the comment:
Example of failure, with additional debug prints:
0:01:02 load avg: 42.13 [ 38/1] test_concurrent_futures failed (env changed)
test_no_stale_references (test.test_concurrent_futures.ProcessPoolSpawnProcessPoolExecutorTest) ... 2.00s reap_children
ok
test_ressources_gced_in_workers (test.test_concurrent_futures.ProcessPoolSpawnProcessPoolExecutorTest) ... 3.86s reap_children
ok
test_shutdown_race_issue12456 (test.test_concurrent_futures.ProcessPoolSpawnProcessPoolExecutorTest) ... 2.22s reap_children
ok
test_submit (test.test_concurrent_futures.ProcessPoolSpawnProcessPoolExecutorTest) ... 2.26s reap_children
ok
test_submit_keyword (test.test_concurrent_futures.ProcessPoolSpawnProcessPoolExecutorTest) ... 1.59s reap_children
ok
test_traceback (test.test_concurrent_futures.ProcessPoolSpawnProcessPoolExecutorTest) ... 1.60s reap_children
ok
MP cleanup: cleanup process
MP cleanup: stop forkserver
MP cleanup: stop res track
MP cleanup: run finalizers
reap_children
----------------------------------------------------------------------
Ran 6 tests in 17.210s
OK
reap_children
Warning -- reap_children() reaped child process 4992
Warning -- multiprocessing.process._dangling was modified by test_concurrent_futures
Before: set()
After: {<weakref at 0x7fedc87bc7d0; to 'SpawnProcess' at 0x7fedc7abcd70>}
----------
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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue38546>
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