Change the default multiprocessing start method away from fork to forkserver or spawn on the remaining platforms where it was fork. See the issue for context. This makes the default far more thread safe (other than for people spawning threads at import time... - don't do that!).
Co-authored-by: blurb-it[bot] <43283697+blurb-it[bot]@users.noreply.github.com>
Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>
The `time.sleep()` call should happen before the GC to give the worker
threads time to clean-up their remaining references to objs.
Additionally, use `support.gc_collect()` instead of `gc.collect()`
just in case the extra GC calls matter.
- re-enable test_fcntl_64_bit on Linux aarch64, but disable it on all
Android ABIs
- use support.setswitchinterval in all relevant tests
- skip test_fma_zero_result on Android x86_64
- accept EACCES when calling os.get_terminal_size on Android
Fix some test_multiprocessing flakiness.
Potentially introduced by https://github.com/python/cpython/pull/25845
not joining that thread likely leads to recently observed "environment
changed" logically passing but overall failing tests seen on some
buildbots similar to:
```
1 test altered the execution environment (env changed):
test.test_multiprocessing_fork.test_processes
2 re-run tests:
test.test_multiprocessing_fork.test_processes
test.test_multiprocessing_forkserver.test_processes
```
This builds on https://github.com/python/cpython/pull/106807, which adds
a return code to ResourceTracker, to make future debugging easier.
Testing this “in situ” proved difficult, since the global ResourceTracker is
involved in test infrastructure. So, the tests here create a new instance and
feed it fake data.
---------
Co-authored-by: Yonatan Bitton <yonatan.bitton@perception-point.io>
Co-authored-by: Yonatan Bitton <bityob@gmail.com>
Co-authored-by: Antoine Pitrou <antoine@python.org>
We add _winapi.BatchedWaitForMultipleObjects to wait for larger numbers of handles.
This is an internal module, hence undocumented, and should be used with caution.
Check the docstring for info before using BatchedWaitForMultipleObjects.
gh-113205: test_multiprocessing.test_terminate: Test the API works on threadpools
Threads can't be forced to terminate (without potentially corrupting too much
state), so the expected behaviour of `ThreadPool.terminate` is to wait for
the currently executing tasks to finish.
The entire test was skipped in GH-110848 (0e9c364f4a).
Instead of skipping it entirely, we should ensure the API eventually succeeds:
use a shorter timeout.
For the record: on my machine, when the test is un-skipped, the task manages to
start in about 1.5% cases.
Add a track parameter to shared memory to allow resource tracking via the side-launched resource tracker process to be disabled on platforms that use it (POSIX).
This allows people who do not want automated cleanup at process exit because they are using the shared memory with processes not participating in Python's resource tracking to use the shared_memory API.
Co-authored-by: Łukasz Langa <lukasz@langa.pl>
Co-authored-by: Guido van Rossum <gvanrossum@gmail.com>
Co-authored-by: Antoine Pitrou <pitrou@free.fr>
Co-authored-by: Gregory P. Smith <greg@krypto.org>
Joining a thread now ensures the underlying OS thread has exited. This is required for safer fork() in multi-threaded processes.
---------
Co-authored-by: blurb-it[bot] <43283697+blurb-it[bot]@users.noreply.github.com>
multiprocessing test_terminate() and test_wait_socket_slow() no
longer test the CI performance: no longer check maximum elapsed time.
Add CLOCK_RES constant: tolerate a difference of 100 ms.
On Windows, multiprocessing Popen.terminate() now catchs
PermissionError and get the process exit code. If the process is
still running, raise again the PermissionError. Otherwise, the
process terminated as expected: store its exit code.
gh-107275 introduced a regression where a SemLock would fail being passed along nested child processes, as the `is_fork_ctx` attribute would be left missing after the first deserialization.
---------
Co-authored-by: blurb-it[bot] <43283697+blurb-it[bot]@users.noreply.github.com>
Co-authored-by: Antoine Pitrou <pitrou@free.fr>
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.
Ensure multiprocessing SemLock is valid for spawn Process before serializing it.
Creating a multiprocessing SemLock with a fork context, and then trying to pass it to a spawn-created Process, would segfault if not detected early.
---------
Co-authored-by: blurb-it[bot] <43283697+blurb-it[bot]@users.noreply.github.com>
Co-authored-by: Antoine Pitrou <pitrou@free.fr>
Prevent `multiprocessing.spawn` from failing to *import* in environments
where `sys.executable` is `None`. This regressed in 3.11 with the addition
of support for path-like objects in multiprocessing.
Adds a test decorator to have tests only run when part of test_multiprocessing_spawn to `_test_multiprocessing.py` so we can start to avoid re-running the same not-global-state specific test in all 3 modes when there is no need.
bpo-17258: `multiprocessing` now supports stronger HMAC algorithms for inter-process connection authentication rather than only HMAC-MD5.
Signed-off-by: Christian Heimes <christian@python.org>
gpshead: I Reworked to be more robust while keeping the idea.
The protocol modification idea remains, but we now take advantage of the
message length as an indicator of legacy vs modern protocol version. No
more regular expression usage. We now default to HMAC-SHA256, but do so
in a way that will be compatible when communicating with older clients
or older servers. No protocol transition period is needed.
More integration tests to verify these claims remain true are required. I'm
unaware of anyone depending on multiprocessing connections between
different Python versions.
---------
Signed-off-by: Christian Heimes <christian@python.org>
Co-authored-by: Gregory P. Smith [Google] <greg@krypto.org>
This starts the process. Users who don't specify their own start method
and use the default on platforms where it is 'fork' will see a
DeprecationWarning upon multiprocessing.Pool() construction or upon
multiprocessing.Process.start() or concurrent.futures.ProcessPool use.
See the related issue and documentation within this change for details.
Tests now call busy_retry() and sleeping_retry() with SHORT_TIMEOUT
or LONG_TIMEOUT (of test.support), rather than hardcoded constants.
Add also WAIT_ACTIVE_CHILDREN_TIMEOUT constant to
_test_multiprocessing.
Gregory P. Smith
Bénédikt Tran
Roy Hyunjin Han
Serhiy Storchaka
Tian Gao
Sam Gross
Malcolm Smith
Miguel Brito
Petr Viktorin
Steve Dower
Xu Song
pan324
Antoine Pitrou
Victor Stinner
albanD
Dong-hee Na
Andrew Geng
Christian Heimes
Jack Hindmarch
Koki Saito
Kumar Aditya
Irit Katriel
Leo Trol
Géry Ogam