New submission from Radosław Szkodziński: multiprocessing.Queue.empty() uses pipe polling on Windows. Unfortunately, pipe semantics on windows are different from POSIX.
The result is either: - Hang when one process tries to get() and another checks for empty() - Falsely returning empty() == False despite nothing being possible to get - because the other process is actually trying to read from the queue. The attached testcase demonstrates the first case, with main process hard hanging on my Python 2.7.8 (anaconda), 32-bit on Windows 7 64-bit. Whether 1 or 2 happens depends on specific program flow. Both can cause deadlocks in code that should be valid. Note that get(block=False) actually works correctly. It is possible that the problem is also present in Python 3. ---------- components: Library (Lib), Windows files: testmp.py messages: 231984 nosy: Radosław.Szkodziński, steve.dower, tim.golden, zach.ware priority: normal severity: normal status: open title: multiprocessing Queue empty() is broken on Windows versions: Python 2.7 Added file: http://bugs.python.org/file37342/testmp.py _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue22976> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
