====================================================================== ERROR: test_get_event_loop_new_process (test.test_asyncio.test_events.TestCGetEventLoop) ---------------------------------------------------------------------- Traceback (most recent call last): File "/home/abuild/rpmbuild/BUILD/Python-3.8.0rc1/Lib/test/test_asyncio/test_events.py", line 2647, in test_get_event_loop_new_process self.loop.run_until_complete(main()), File "/home/abuild/rpmbuild/BUILD/Python-3.8.0rc1/Lib/asyncio/base_events.py", line 608, in run_until_complete return future.result() File "/home/abuild/rpmbuild/BUILD/Python-3.8.0rc1/Lib/test/test_asyncio/test_events.py", line 2640, in main pool = concurrent.futures.ProcessPoolExecutor() File "/home/abuild/rpmbuild/BUILD/Python-3.8.0rc1/Lib/concurrent/futures/process.py", line 555, in __init__ self._call_queue = _SafeQueue( File "/home/abuild/rpmbuild/BUILD/Python-3.8.0rc1/Lib/concurrent/futures/process.py", line 165, in __init__ super().__init__(max_size, ctx=ctx) File "/home/abuild/rpmbuild/BUILD/Python-3.8.0rc1/Lib/multiprocessing/queues.py", line 42, in __init__ self._rlock = ctx.Lock() File "/home/abuild/rpmbuild/BUILD/Python-3.8.0rc1/Lib/multiprocessing/context.py", line 68, in Lock return Lock(ctx=self.get_context()) File "/home/abuild/rpmbuild/BUILD/Python-3.8.0rc1/Lib/multiprocessing/synchronize.py", line 162, in __init__ SemLock.__init__(self, SEMAPHORE, 1, 1, ctx=ctx) File "/home/abuild/rpmbuild/BUILD/Python-3.8.0rc1/Lib/multiprocessing/synchronize.py", line 57, in __init__ sl = self._semlock = _multiprocessing.SemLock( OSError: [Errno 38] Function not implemented ====================================================================== ERROR: test_get_event_loop_new_process (test.test_asyncio.test_events.TestPyGetEventLoop) ---------------------------------------------------------------------- Traceback (most recent call last): File "/home/abuild/rpmbuild/BUILD/Python-3.8.0rc1/Lib/test/test_asyncio/test_events.py", line 2647, in test_get_event_loop_new_process self.loop.run_until_complete(main()), File "/home/abuild/rpmbuild/BUILD/Python-3.8.0rc1/Lib/asyncio/base_events.py", line 608, in run_until_complete return future.result() File "/home/abuild/rpmbuild/BUILD/Python-3.8.0rc1/Lib/test/test_asyncio/test_events.py", line 2640, in main pool = concurrent.futures.ProcessPoolExecutor() File "/home/abuild/rpmbuild/BUILD/Python-3.8.0rc1/Lib/concurrent/futures/process.py", line 555, in __init__ self._call_queue = _SafeQueue( File "/home/abuild/rpmbuild/BUILD/Python-3.8.0rc1/Lib/concurrent/futures/process.py", line 165, in __init__ super().__init__(max_size, ctx=ctx) File "/home/abuild/rpmbuild/BUILD/Python-3.8.0rc1/Lib/multiprocessing/queues.py", line 42, in __init__ self._rlock = ctx.Lock() File "/home/abuild/rpmbuild/BUILD/Python-3.8.0rc1/Lib/multiprocessing/context.py", line 68, in Lock return Lock(ctx=self.get_context()) File "/home/abuild/rpmbuild/BUILD/Python-3.8.0rc1/Lib/multiprocessing/synchronize.py", line 162, in __init__ SemLock.__init__(self, SEMAPHORE, 1, 1, ctx=ctx) File "/home/abuild/rpmbuild/BUILD/Python-3.8.0rc1/Lib/multiprocessing/synchronize.py", line 57, in __init__ sl = self._semlock = _multiprocessing.SemLock( OSError: [Errno 38] Function not implemented ---------------------------------------------------------------------- The problem is that in the OpenBuildService (the build system of SUSE distributions) /dev/shm is limited to: abuild@milic:~/rpmbuild/BUILD/Python-3.8.0rc1> ls -ld /dev/shm drwxr-xr-x 1 root root 0 Oct 5 13:23 /dev/shm abuild@milic:~/rpmbuild/BUILD/Python-3.8.0rc1> Provided PR will skip test if /dev/shm doesn’t exist or it doesn’t sufficient permissions.

 New changeset ddbeb2f3e02a510c5784ffd74c5e09e8c70b5881 by Victor Stinner in branch 'master': bpo-38377: Add support.skip_if_broken_multiprocessing_synchronize() (GH-20944) https://github.com/python/cpython/commit/ddbeb2f3e02a510c5784ffd74c5e09e8c70b5881 

 New changeset b1e736113484c99acb57e4acb417b91a9e58e7ff by Victor Stinner in branch '3.9': bpo-38377: Add support.skip_if_broken_multiprocessing_synchronize() (GH-20944) (GH-20962) https://github.com/python/cpython/commit/b1e736113484c99acb57e4acb417b91a9e58e7ff 

 New changeset e8056180a13b6755e4e3e5505b7bf03f79da29fb by Victor Stinner in branch '3.8': bpo-38377: Add support.skip_if_broken_multiprocessing_synchronize() (GH-20944) (GH-20962) (GH-20966) https://github.com/python/cpython/commit/e8056180a13b6755e4e3e5505b7bf03f79da29fb 

Hum, test_resource_tracker_reused() failed twice on macOS, but it's unclear to me if it's a regression caused by my change or not. x86-64 macOS 3.9: https://buildbot.python.org/all/#builders/696/builds/119 FAIL: test_resource_tracker_reused (test.test_multiprocessing_forkserver.TestResourceTracker) ---------------------------------------------------------------------- Traceback (most recent call last): File "/Users/buildbot/buildarea/3.9.billenstein-macos/build/Lib/test/_test_multiprocessing.py", line 5219, in test_resource_tracker_reused self.assertTrue(is_resource_tracker_reused) AssertionError: False is not true

> Hum, test_resource_tracker_reused() failed twice on macOS, but it's unclear to me if it's a regression caused by my change or not. It does appear to be caused by your change. I did a quick check with the 3.8 branch. With that PR, test_multiprocessing_forkserver fails solidly. Backing up to the previous commit, test_multiprocessing_forkserver passes.

test_multiprocessing_forkserver.test_resource_tracker_reused() failed on 3.8, 3.9 and master buildbots. It looks like a real reproducible bug. I'm not sure how my change triggered this bug.

From what I understood, the problem is that creating a SemLock has an impact on the resource tracker. The failing unit tests checks something about the resource tracker. The test runs a function in a child process. The function is defined in _test_multiprocessing.py. _test_multiprocessing.py calls skip_if_broken_multiprocessing_synchronize() which creates a SemLock(). At the end, the child process modifies the resource tracker because it creates a SemLock(). There are different options to fix the issue: * Modify skip_if_broken_multiprocessing_synchronize() only only attempt to create a SemLock on Linux. * Modify skip_if_broken_multiprocessing_synchronize() to only check if the current user is allowed to write into /dev/shm/ directory: that would allow touching the resource tracker. * Modify the test to avoid improting _test_multiprocessing in the child process. I don't know why the test only fails on macOS. Note: I ignored macOS failure when I merged my PR because the macOS job of GitHub Action is failing randomly for at least 3 months and nobody attempted to fix it. So I learnt to ignore this job.

 New changeset 3358da4054b9b0b045eb47dc74dee3d58bfbb1d5 by Victor Stinner in branch 'master': bpo-38377: Fix skip_if_broken_multiprocessing_synchronize() on macOS (GH-20984) https://github.com/python/cpython/commit/3358da4054b9b0b045eb47dc74dee3d58bfbb1d5 

 New changeset ec9bc2da421c456e416d991fd1fe79ac33344d9d by Miss Islington (bot) in branch '3.8': bpo-38377: Fix skip_if_broken_multiprocessing_synchronize() on macOS (GH-20984) https://github.com/python/cpython/commit/ec9bc2da421c456e416d991fd1fe79ac33344d9d 

 New changeset 1529322ca6b7b029af65aceeb04e6d47013eeeb4 by Miss Islington (bot) in branch '3.9': bpo-38377: Fix skip_if_broken_multiprocessing_synchronize() on macOS (GH-20984) https://github.com/python/cpython/commit/1529322ca6b7b029af65aceeb04e6d47013eeeb4 

Ok, macOS buildbots are back to green, I close the issue.