[issue32937] Multiprocessing worker functions not terminating with a large number of processes and a manager
EricG <ericg...@gmail.com> added the comment: Making some further observations, when I set processes = 12, for example, I can see 12 separate python processes + 4 additional processes also created which I assume are setup for the manager and, perhaps, other purposes. Now, what makes these 4 additional processes interesting is that for me, multiprocessing.cpu_count() returns 24. And, it is when I set processes = 20 that the python code will sometimes terminate successfully. 20 + 4 = 24...so I am using every single cpu in that situation. However, as noted, when I set processes = 19, it will always terminate successfully. 19 + 4 < 24...there is at least one cpu not assigned any work. Perhaps there some some kind of race condition or swapping around of data structures or something that only happens on macOS when every cpu is in use by python for this purpose. -- ___ Python tracker <rep...@bugs.python.org> <https://bugs.python.org/issue32937> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue32937] Multiprocessing worker functions not terminating with a large number of processes and a manager
EricG <ericg...@gmail.com> added the comment: If I do: from queue import Queue messages = Queue() No messages are printed. I believe this is expected as a regular Queue cannot be shared between processes. It was a problem that the manager was designed to solve. I am using a MacPro running 10.3.2 Python 3.6.4 It would not surprise me if this were an OS specific issue. To reproduce it may requiring using a Mac with a high number of cores. It is trivially reproducible for me. -- ___ Python tracker <rep...@bugs.python.org> <https://bugs.python.org/issue32937> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue32937] Multiprocessing worker functions not terminating with a large number of processes and a manager
EricG <ericg...@gmail.com> added the comment: I do plan to consume the messages on the queue, but only after all worker functions are complete...after pool.join() returns. Is this not ok? I can certainly spawn a thread on the main process which will consume the queue entries and insert them into a list or queue which can then be accessed after join returns. Is that the correct way this code should be written? -- ___ Python tracker <rep...@bugs.python.org> <https://bugs.python.org/issue32937> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
