[issue6433] multiprocessing: pool.map hangs on empty list

Changes by Jesse Noller : -- resolution: -> fixed status: open -> closed ___ Python tracker ___ ___ Python-bugs-list mailing list Unsu

[issue6433] multiprocessing: pool.map hangs on empty list

Jesse Noller added the comment: committed r74023 on trunk -- ___ Python tracker ___ ___ Python-bugs-list mailing list Unsubscribe: ht

[issue6433] multiprocessing: pool.map hangs on empty list

Jesse Noller added the comment: It's on my list for this week. -- ___ Python tracker ___ ___ Python-bugs-list mailing list Unsubscribe

[issue6433] multiprocessing: pool.map hangs on empty list

Eric Eisner added the comment: Can anyone review this patch? It is a very simple fix to catch this one edge case. As this can cause multiprocessing to enter a state where it needs to be externally killed, it would be good if this made 2.6.3. -- ___ P

[issue6433] multiprocessing: pool.map hangs on empty list

Changes by Jesse Noller : -- assignee: -> jnoller ___ Python tracker ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.p

[issue6433] multiprocessing: pool.map hangs on empty list

Changes by R. David Murray : -- nosy: +jnoller ___ Python tracker ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.pytho

[issue6433] multiprocessing: pool.map hangs on empty list

Eric Eisner added the comment: A few lines before this patch the code turns iterable into a list if it does not hasattr('__len__') for the purpose of calculating the chunksize. -- ___ Python tracker ___

[issue6433] multiprocessing: pool.map hangs on empty list

Ezio Melotti added the comment: I'm not familiar with multiprocessing but I gave a quick look at the patch. If the 'iterable' is an iterator/generator "if len(iterable) == 0:" may fail since these objects don't usually have a __len__. More tests for this situation are probably needed too. -

[issue6433] multiprocessing: pool.map hangs on empty list

New submission from Eric Eisner : In multiprocessing, if you give a pool.map a zero-length iterator and specify a nonzero chunksize, the process hangs indefinitely. Example: import multiprocessing pool = multiprocessing.Pool() pool.map(len, [], chunksize=1) # hang forever Attached simple testca