gh-108388: Split test_multiprocessing_spawn

[vstinner]

Split test_multiprocessing_fork, test_multiprocessing_forkserver and test_multiprocessing_spawn into test packages. Each package is made of 4 sub-tests: processes, threads, manager and misc. It allows running more tests in parallel and so reduce the total test duration.

• Issue: Split long running test suites up into smaller sub suites to reduce our regrtest long tail on multi-core systems. #108388

[vstinner]

Example running 4 slow tests:

./python -m test test_asyncio test_multiprocessing_fork test_multiprocessing_forkserver test_multiprocessing_spawn -j0 --slowest 

Timing (reference => this PR): 3 min 22 sec => 2 min 22 sec (-1 min)

On the main branch:

10 slowest tests: - test_multiprocessing_spawn: 3 min 22 sec - test_asyncio: 2 min 10 sec - test_multiprocessing_forkserver: 1 min 43 sec - test_multiprocessing_fork: 1 min 17 sec Total duration: 3 min 22 sec 

With this PR + PR #108393 (needed for this test):

40 tests OK. 10 slowest tests: - test_multiprocessing_spawn.test_processes: 2 min 3 sec - test_multiprocessing_forkserver.test_processes: 1 min 41 sec - test_multiprocessing_spawn.test_misc: 1 min 22 sec - test_multiprocessing_spawn.test_manager: 1 min 2 sec - test_multiprocessing_forkserver.test_misc: 54.3 sec - test_asyncio.test_tasks: 52.9 sec - test_multiprocessing_forkserver.test_manager: 45.5 sec - test_multiprocessing_fork.test_processes: 43.4 sec - test_asyncio.test_events: 39.3 sec - test_multiprocessing_fork.test_misc: 26.3 sec 2 tests skipped: test_asyncio.test_windows_events test_asyncio.test_windows_utils Total duration: 2 min 22 sec 

All CPUs are well used, the system load peak is 12.33 which is a good thing (the machine has 12 threads/6 cores).

Full logs:

Details

vstinner@mona$ ./python -m test test_asyncio test_multiprocessing_fork test_multiprocessing_forkserver test_multiprocessing_spawn -j0 --slowest 0:00:00 load avg: 6.17 Run tests in parallel using 14 child processes 0:00:01 load avg: 6.17 [ 1/42] test_asyncio.test_protocols passed 0:00:01 load avg: 6.17 [ 2/42] test_asyncio.test_futures2 passed 0:00:01 load avg: 6.17 [ 3/42] test_asyncio.test_buffered_proto passed 0:00:01 load avg: 6.17 [ 4/42] test_asyncio.test_context passed 0:00:01 load avg: 6.17 [ 5/42] test_asyncio.test_pep492 passed 0:00:02 load avg: 6.17 [ 6/42] test_asyncio.test_runners passed 0:00:02 load avg: 6.17 [ 7/42] test_asyncio.test_proactor_events passed 0:00:02 load avg: 6.17 [ 8/42] test_asyncio.test_queues passed 0:00:03 load avg: 6.17 [ 9/42] test_asyncio.test_server passed 0:00:03 load avg: 6.17 [10/42] test_asyncio.test_selector_events passed 0:00:03 load avg: 6.17 [11/42] test_asyncio.test_eager_task_factory passed 0:00:04 load avg: 6.80 [12/42] test_asyncio.test_locks passed 0:00:04 load avg: 6.80 [13/42] test_asyncio.test_threads passed 0:00:06 load avg: 6.80 [14/42] test_asyncio.test_timeouts passed 0:00:06 load avg: 6.80 [15/42] test_asyncio.test_transports passed 0:00:07 load avg: 6.80 [16/42] test_asyncio.test_streams passed 0:00:07 load avg: 6.80 [17/42] test_asyncio.test_windows_events skipped test_asyncio.test_windows_events skipped -- Windows only 0:00:07 load avg: 6.80 [18/42] test_asyncio.test_base_events passed 0:00:07 load avg: 6.80 [19/42] test_asyncio.test_sslproto passed 0:00:07 load avg: 6.80 [20/42] test_asyncio.test_windows_utils skipped test_asyncio.test_windows_utils skipped -- Windows only 0:00:08 load avg: 6.80 [21/42] test_asyncio.test_unix_events passed 0:00:09 load avg: 7.70 [22/42] test_asyncio.test_waitfor passed 0:00:10 load avg: 7.70 [23/42] test_asyncio.test_sock_lowlevel passed 0:00:10 load avg: 7.70 [24/42] test_asyncio.test_sendfile passed 0:00:11 load avg: 7.70 [25/42] test_asyncio.test_taskgroups passed 0:00:12 load avg: 7.70 [26/42] test_asyncio.test_futures passed 0:00:18 load avg: 8.68 [27/42] test_asyncio.test_ssl passed 0:00:28 load avg: 10.42 [28/42] test_multiprocessing_fork.test_threads passed 0:00:29 load avg: 11.02 [29/42] test_asyncio.test_subprocess passed Unknown child process pid 313199, will report returncode 255 Loop <_UnixSelectorEventLoop running=False closed=True debug=False> that handles pid 313199 is closed 0:00:32 load avg: 11.02 [30/42] test_multiprocessing_fork.test_manager passed -- running: test_asyncio.test_events (32.0 sec) /home/vstinner/python/main/Lib/multiprocessing/popen_fork.py:66: DeprecationWarning: This process (pid=310261) is multi-threaded, use of fork() may lead to deadlocks in the child. self.pid = os.fork() /home/vstinner/python/main/Lib/multiprocessing/popen_fork.py:66: DeprecationWarning: This process (pid=313364) is multi-threaded, use of fork() may lead to deadlocks in the child. self.pid = os.fork() 0:00:32 load avg: 11.02 [31/42] test_multiprocessing_forkserver.test_threads passed -- running: test_asyncio.test_events (32.9 sec) 0:00:34 load avg: 11.50 [32/42] test_multiprocessing_fork.test_misc passed -- running: test_asyncio.test_events (34.6 sec), test_asyncio.test_tasks (31.7 sec) /home/vstinner/python/main/Lib/multiprocessing/popen_fork.py:66: DeprecationWarning: This process (pid=313266) is multi-threaded, use of fork() may lead to deadlocks in the child. self.pid = os.fork() 0:00:40 load avg: 12.02 [33/42] test_asyncio.test_events passed (39.3 sec) -- running: test_multiprocessing_forkserver.test_misc (30.9 sec), test_asyncio.test_tasks (37.1 sec), test_multiprocessing_fork.test_processes (32.4 sec), test_multiprocessing_forkserver.test_manager (31.1 sec) 0:00:51 load avg: 12.33 [34/42] test_multiprocessing_spawn.test_threads passed -- running: test_multiprocessing_forkserver.test_processes (40.9 sec), test_multiprocessing_spawn.test_processes (32.8 sec), test_multiprocessing_forkserver.test_misc (42.1 sec), test_multiprocessing_spawn.test_misc (38.9 sec), test_asyncio.test_tasks (48.2 sec), test_multiprocessing_fork.test_processes (43.5 sec), test_multiprocessing_spawn.test_manager (39.7 sec), test_multiprocessing_forkserver.test_manager (42.2 sec) 0:00:51 load avg: 12.33 [35/42] test_multiprocessing_fork.test_processes passed (43.4 sec) -- running: test_multiprocessing_forkserver.test_processes (41.5 sec), test_multiprocessing_spawn.test_processes (33.5 sec), test_multiprocessing_forkserver.test_misc (42.7 sec), test_multiprocessing_spawn.test_misc (39.5 sec), test_asyncio.test_tasks (48.8 sec), test_multiprocessing_spawn.test_manager (40.4 sec), test_multiprocessing_forkserver.test_manager (42.9 sec) /home/vstinner/python/main/Lib/multiprocessing/popen_fork.py:66: DeprecationWarning: This process (pid=310329) is multi-threaded, use of fork() may lead to deadlocks in the child. self.pid = os.fork() /home/vstinner/python/main/Lib/multiprocessing/popen_fork.py:66: DeprecationWarning: This process (pid=310329) is multi-threaded, use of fork() may lead to deadlocks in the child. self.pid = os.fork() 0:00:55 load avg: 12.06 [36/42] test_multiprocessing_forkserver.test_manager passed (45.5 sec) -- running: test_multiprocessing_forkserver.test_processes (45.0 sec), test_multiprocessing_spawn.test_processes (37.0 sec), test_multiprocessing_forkserver.test_misc (46.2 sec), test_multiprocessing_spawn.test_misc (43.0 sec), test_asyncio.test_tasks (52.3 sec), test_multiprocessing_spawn.test_manager (43.9 sec) 0:00:56 load avg: 12.06 [37/42] test_asyncio.test_tasks passed (52.9 sec) -- running: test_multiprocessing_forkserver.test_processes (46.3 sec), test_multiprocessing_spawn.test_processes (38.2 sec), test_multiprocessing_forkserver.test_misc (47.5 sec), test_multiprocessing_spawn.test_misc (44.3 sec), test_multiprocessing_spawn.test_manager (45.1 sec) 0:01:04 load avg: 10.75 [38/42] test_multiprocessing_forkserver.test_misc passed (54.3 sec) -- running: test_multiprocessing_forkserver.test_processes (53.8 sec), test_multiprocessing_spawn.test_processes (45.7 sec), test_multiprocessing_spawn.test_misc (51.8 sec), test_multiprocessing_spawn.test_manager (52.6 sec) 0:01:14 load avg: 9.63 [39/42] test_multiprocessing_spawn.test_manager passed (1 min 2 sec) -- running: test_multiprocessing_forkserver.test_processes (1 min 4 sec), test_multiprocessing_spawn.test_processes (56.1 sec), test_multiprocessing_spawn.test_misc (1 min 2 sec) 0:01:35 load avg: 12.00 [40/42] test_multiprocessing_spawn.test_misc passed (1 min 22 sec) -- running: test_multiprocessing_forkserver.test_processes (1 min 24 sec), test_multiprocessing_spawn.test_processes (1 min 16 sec) 0:01:52 load avg: 13.34 [41/42] test_multiprocessing_forkserver.test_processes passed (1 min 41 sec) -- running: test_multiprocessing_spawn.test_processes (1 min 34 sec) 0:02:22 load avg: 8.84 running: test_multiprocessing_spawn.test_processes (2 min 4 sec) 0:02:22 load avg: 8.84 [42/42] test_multiprocessing_spawn.test_processes passed (2 min 3 sec) == Tests result: SUCCESS == 40 tests OK. 10 slowest tests: - test_multiprocessing_spawn.test_processes: 2 min 3 sec - test_multiprocessing_forkserver.test_processes: 1 min 41 sec - test_multiprocessing_spawn.test_misc: 1 min 22 sec - test_multiprocessing_spawn.test_manager: 1 min 2 sec - test_multiprocessing_forkserver.test_misc: 54.3 sec - test_asyncio.test_tasks: 52.9 sec - test_multiprocessing_forkserver.test_manager: 45.5 sec - test_multiprocessing_fork.test_processes: 43.4 sec - test_asyncio.test_events: 39.3 sec - test_multiprocessing_fork.test_misc: 26.3 sec 2 tests skipped: test_asyncio.test_windows_events test_asyncio.test_windows_utils Total duration: 2 min 22 sec 

[gpshead]

This function needs proper documentation as to what it does and how it behaves. The new parameters behaviors are unobvious.

[miss-islington]

Thanks @vstinner for the PR 🌮🎉.. I'm working now to backport this PR to: 3.12.
🐍🍒⛏🤖

[bedevere-bot]

GH-108442 is a backport of this pull request to the 3.12 branch.

[miss-islington]

Thanks @vstinner for the PR 🌮🎉.. I'm working now to backport this PR to: 3.11.
🐍🍒⛏🤖

[bedevere-app]

GH-109688 is a backport of this pull request to the 3.11 branch.