Fixes a hang in multiprocessing process pool executor when a child process crashes and code could otherwise block on writing to the pipe. See GH-94777 for more details.
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.
Do not spawn ProcessPool workers on demand when they spawn via fork.
This avoids potential deadlocks in the child processes due to forking from
a multithreaded process.
Prevent `max_tasks_per_child` use with a "fork" mp_context to avoid deadlocks.
Also defaults to "spawn" when no mp_context is supplied for safe convenience.
* Fix test_concurrent_futures to actually test what it says.
Many ProcessPoolExecutor based tests were ignoring the mp_context
and using the default instead. This meant we lacked proper test
coverage of all of them.
Also removes the old _prime_executor() worker delay seeding code
as it appears to have no point and causes 20-30 seconds extra
latency on this already long test. It also interfered with some
of the refactoring to fix the above to not needlessly create their
own executor when setUp has already created an appropriate one.
* Don't import the name from multiprocessing directly to avoid confusion.
* 📜🤖 Added by blurb_it.
Co-authored-by: blurb-it[bot] <43283697+blurb-it[bot]@users.noreply.github.com>
Skip tests on ASAN and/or MSAN builds:
* multiprocessing tests
* test___all__
* test_concurrent_futures
* test_decimal
* test_peg_generator
* test_tools
The ASAN job of GitHub Actions no longer excludes these tests.
* bpo-20369: concurrent.futures.wait() now deduplicates futures given as arg.
* 📜🤖 Added by blurb_it.
Co-authored-by: blurb-it[bot] <43283697+blurb-it[bot]@users.noreply.github.com>
Instead of explicitly enumerate test classes for run_unittest()
use the unittest ability to discover tests. This also makes these
tests discoverable and runnable with unittest.
load_tests() can be used for dynamic generating tests and adding
doctests. setUpModule(), tearDownModule() and addModuleCleanup()
can be used for running code before and after all module tests.
In the case of multiprocessing.synchronize() being missing, the
test_concurrent_futures test suite now skips only the tests that
require multiprocessing.synchronize().
Validate that multiprocessing.synchronize exists as part of
_check_system_limits(), allowing ProcessPoolExecutor to raise
NotImplementedError during __init__, rather than crashing with
ImportError during __init__ when creating a lock imported from
multiprocessing.synchronize.
Use _check_system_limits() to disable tests of
ProcessPoolExecutor on systems without multiprocessing.synchronize.
Running the test suite without multiprocessing.synchronize reveals
that Lib/compileall.py crashes when it uses a ProcessPoolExecutor.
Therefore, change Lib/compileall.py to call _check_system_limits()
before creating the ProcessPoolExecutor.
Note that both Lib/compileall.py and Lib/test/test_compileall.py
were attempting to sanity-check ProcessPoolExecutor by expecting
ImportError. In multiprocessing.resource_tracker, sem_unlink() is also absent
on platforms where POSIX semaphores aren't available. Avoid using
sem_unlink() if it, too, does not exist.
Co-authored-by: Pablo Galindo <Pablogsal@gmail.com>
On Linux, skip tests using multiprocessing if the current user cannot
create a file in /dev/shm/ directory. Add the
skip_if_broken_multiprocessing_synchronize() function to the
test.support module.
Now only test_error_during_result_unpickle_in_result_handler()
captures and ignores sys.stderr in the test process.
Tools like test.bisect_cmd don't support subTest() but only
work with the granularity of one method.
Remove unused ExecutorDeadlockTest._sleep_id() method.
As reported initially by @rad-pat in #6084, the following script causes a deadlock.
```
from concurrent.futures import ProcessPoolExecutor
class ObjectWithPickleError():
"""Triggers a RuntimeError when sending job to the workers"""
def __reduce__(self):
raise RuntimeError()
if __name__ == "__main__":
e = ProcessPoolExecutor()
f = e.submit(id, ObjectWithPickleError())
e.shutdown(wait=False)
f.result() # Deadlock on get
```
This is caused by the fact that the main process is closing communication channels that might be necessary to the `queue_management_thread` later. To avoid this, this PR let the `queue_management_thread` manage all the closing.
https://bugs.python.org/issue39104
Automerge-Triggered-By: @pitrou
Fix test_ressources_gced_in_workers() of test_concurrent_futures:
explicitly stop the manager to prevent leaking a child process
running in the background after the test completes.
Multiprocessing and concurrent.futures tests now stop the resource
tracker process when tests complete.
Add ResourceTracker._stop() method to
multiprocessing.resource_tracker.
Add _cleanup_tests() helper function to multiprocessing.util: share
code between multiprocessing and concurrent.futures tests.
Replace hardcoded timeout constants in tests with SHORT_TIMEOUT of
test.support, so it's easier to ajdust this timeout for all tests at
once.
SHORT_TIMEOUT is 30 seconds by default, but it can be longer
depending on --timeout command line option.
The change makes almost all timeouts longer, except
test_reap_children() of test_support which is made 2x shorter:
SHORT_TIMEOUT should be enough. If this test starts to fail,
LONG_TIMEOUT should be used instead.
Uniformize also "from test import support" import in some test files.
test_concurrent_futures now cleans up multiprocessing to remove
immediately temporary directories created by
multiprocessing.util.get_temp_dir().
The test now uses setUpModule() and tearDownModule().
* Fixes issue 24882
* Add news file entry for change.
* Change test_concurrent_futures.ThreadPoolShutdownTest
Adjust the shutdown test so that, after submitting three jobs
to the executor, the test checks for less than three threads,
instead of looking for exactly three threads.
If idle threads are being recycled properly, then we should have
less than three threads.
* Switched idle count to semaphor, Updated tests
As suggested by reviewer tomMoral, swapped lock-protected counter
with a semaphore to track the number of unused threads.
Adjusted test_threads_terminate to wait for completiton of the
previous future before submitting a new one (and checking the
number of threads used).
Also added a new test to confirm the thread pool can be saturated.
* Updates tests as requested by pitrou.
* Correct minor whitespace error.
* Make test_saturation faster
Wrap the callback call within the `add_done_callback` function within concurrent.futures, in order to behave in an identical manner to callbacks added to a running future are triggered once it has completed.
Deprecated passing the following arguments as keyword arguments:
- "func" in functools.partialmethod(), weakref.finalize(),
profile.Profile.runcall(), cProfile.Profile.runcall(),
bdb.Bdb.runcall(), trace.Trace.runfunc() and
curses.wrapper().
- "function" in unittest.addModuleCleanup() and
unittest.TestCase.addCleanup().
- "fn" in the submit() method of concurrent.futures.ThreadPoolExecutor
and concurrent.futures.ProcessPoolExecutor.
- "callback" in contextlib.ExitStack.callback(),
contextlib.AsyncExitStack.callback() and
contextlib.AsyncExitStack.push_async_callback().
- "c" and "typeid" in the create() method of multiprocessing.managers.Server
and multiprocessing.managers.SharedMemoryServer.
- "obj" in weakref.finalize().
Also allowed to pass arbitrary keyword arguments (even "self" and "func")
if the above arguments are passed as positional argument.
Future.set_result and Future.set_exception now raise InvalidStateError
if the futures are not pending or running. This mirrors the behavior
of asyncio.Future, and prevents AssertionErrors in asyncio.wrap_future
when set_result is called multiple times.
Executors in concurrent.futures accepted tasks after executor was shutdown by interpreter exit. Tasks were left in PENDING state forever. This fix changes submit to instead raise a RuntimeError.
Fix deadlocks in :class:`concurrent.futures.ProcessPoolExecutor` when task arguments or results cause pickling or unpickling errors.
This should make sure that calls to the :class:`ProcessPoolExecutor` API always eventually return.
This was possible before. GH-1560 introduced a regression after 3.6.2 got
released where only sequences were accepted now. This commit addresses this
problem.
Louis Paulot
yonatanp
Gregory P. Smith
JosephSBoyle
Thomas Grainger
Florian Bruhin
Victor Stinner
Kumar Aditya
Logan Jones
nullptr
Serhiy Storchaka
Asheesh Laroia
Hai Shi
Christian Heimes
Kyle Stanley
Thomas Moreau
Brian Quinlan
Victor Stinner
Inada Naoki
Sean
Sam Martin
Pablo Galindo
jhaydaman
Mark Nemec
Leo Arias
Antoine Pitrou
Łukasz Langa
Victor Stinner