[issue14406] Race condition in concurrent.futures
Changes by Ralf Schmitt python-b...@systemexit.de: -- nosy: +schmir ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue14406 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue14406] Race condition in concurrent.futures
Ralf Schmitt added the comment: I think having a lock here is unnecessary. The following code should work: def _decrement_pending_calls(self): if self.num_pending_calls == len(self.finished_futures): self.event.set() (well, maybe the method should also be renamed then) -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue14406 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue14406] Race condition in concurrent.futures
Matt Joiner anacro...@gmail.com added the comment: Patch with a test included. Being a nondeterministic bug, please adjust the thread count, or timing as necessary, the parameters in the patch are as low as I can get them and still reasonably reproduce the bug (linux 3.2, i386). There's a few complications in testing this. Firstly timeouts cannot be used, because at the end of the timeout, all the futures are checked to categorize them into done and not done. Except for taking the entire duration of the timeout given to return, the bug is masked in this case. Secondly, it can't be known how long a wait *should* take, so failing after some duration and assuming a stall due to the race decrementing num_pending_calls would be a guess dependent on the capabilities of the system. If a timeout needs to be added (and fired from an outside thread for reasons given above), please let me know, and direct me to an example of this kind of testing elsewhere in the stdlib, so I can do this idiomatically. Without applying the patch, the test case provided will (usually) hang indefinitely. -- Added file: http://bugs.python.org/file25078/concurrent.futures._AllCompletedWaiter.num_pending_calls-race-test.patch ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue14406 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue14406] Race condition in concurrent.futures
Roundup Robot devn...@psf.upfronthosting.co.za added the comment: New changeset 0312db5265d0 by Antoine Pitrou in branch '3.2': Issue #14406: Fix a race condition when using `concurrent.futures.wait(return_when=ALL_COMPLETED)`. http://hg.python.org/cpython/rev/0312db5265d0 New changeset 2c1432552213 by Antoine Pitrou in branch 'default': Issue #14406: Fix a race condition when using `concurrent.futures.wait(return_when=ALL_COMPLETED)`. http://hg.python.org/cpython/rev/2c1432552213 -- nosy: +python-dev ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue14406 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue14406] Race condition in concurrent.futures
Antoine Pitrou pit...@free.fr added the comment: The patch looks fine, I've committed it. Thanks! -- resolution: - fixed stage: - committed/rejected status: open - closed ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue14406 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue14406] Race condition in concurrent.futures
Antoine Pitrou pit...@free.fr added the comment: Could your patch also include a proper test case in Lib/test/test_concurrent_futures.py ? -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue14406 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue14406] Race condition in concurrent.futures
Matt Joiner anacro...@gmail.com added the comment: I'll add this shortly. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue14406 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue14406] Race condition in concurrent.futures
New submission from Matt Joiner anacro...@gmail.com: There's a race condition in concurrent.futures in _AllCompletedWaiter, which affects wait(return_when=ALL_COMPLETED). The attached test will go into an infinite wait. -- components: Library (Lib) files: concurrent.futures._AllCompletedWaiter-race-condition-test.py messages: 156764 nosy: anacrolix priority: normal severity: normal status: open title: Race condition in concurrent.futures type: behavior versions: Python 3.2, Python 3.3 Added file: http://bugs.python.org/file25019/concurrent.futures._AllCompletedWaiter-race-condition-test.py ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue14406 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue14406] Race condition in concurrent.futures
Matt Joiner anacro...@gmail.com added the comment: Patch attached. -- keywords: +patch Added file: http://bugs.python.org/file25020/concurrent.futures._AllCompletedWaiter-race-condition.patch ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue14406 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue14406] Race condition in concurrent.futures
Changes by Matt Joiner anacro...@gmail.com: -- nosy: +bquinlan, loewis, pitrou, rosslagerwall ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue14406 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
