Adding the `rtype_cache` to the `warnings.warn` message improves the
previous, somewhat vague message from
```
/Users/username/cpython/Lib/multiprocessing/resource_tracker.py:224: UserWarning: resource_tracker: There appear to be 6 leaked semaphore objects to clean up at shutdown
```
to
```
/Users/username/cpython/Lib/multiprocessing/resource_tracker.py:224: UserWarning: resource_tracker: There appear to be 6 leaked semaphore objects to clean up at shutdown: {'/mp-yor5cvj8', '/mp-10jx8eqr', '/mp-eobsx9tt', '/mp-0lml23vl', '/mp-9dgtsa_m', '/mp-frntyv4s'}
```
---------
Co-authored-by: blurb-it[bot] <43283697+blurb-it[bot]@users.noreply.github.com>
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>
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.
The multiprocessing.resource_tracker replaces the multiprocessing.semaphore_tracker module. Other than semaphores, resource_tracker also tracks shared_memory segments. Patch by Pierre Glaser.
Antoine Pitrou
shailshouryya
Koki Saito
Asheesh Laroia
Victor Stinner
Pierre Glaser