multiprocessing.pool: Fix return of map_async()#3378
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srittau merged 2 commits intopython:masterfrom Oct 17, 2019
semgrep:nbrahms/fix_map_async_return_type
Merged
multiprocessing.pool: Fix return of map_async()#3378srittau merged 2 commits intopython:masterfrom semgrep:nbrahms/fix_map_async_return_type
srittau merged 2 commits intopython:masterfrom
semgrep:nbrahms/fix_map_async_return_type
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This commit fixes the issue raised in #3377. Inspecting the multiprocessing code, it appears that MapResult is a minimal extension of AsyncResult, so I choose to remove the extra List[] type from its generic argument (alternatively one could remove it from the return type of map_async() itself, but this seems incorrect as map() has a return type of List[]). The multiprocessing.pool API appears not to have changed at least since 2.7, so this change should work for both Python 2 and 3.
srittau
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Oct 17, 2019
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srittau
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Thanks! I think it would make more sense to leave MapResult unchanged, since MapResults always use list values for ApplyResult. Instead, remove the spurious List from map_async()'s return type.
On returning to the multiprocessing.pool code, I see that MapResult does indeed always return a List type. Therefore, to fix the doubly nested list in multiprocessing.pool.map_async, we should remove the spurious List type from the map_async def instead.
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Hi @srittau ... I just looked at the class MapResult(ApplyResult):
def __init__(self, cache, chunksize, length, callback, error_callback):
ApplyResult.__init__(self, cache, callback,
error_callback=error_callback)
self._success = True
self._value = [None] * lengthI've updated the PR per your request. |
srittau
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Oct 17, 2019
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This commit fixes the issue raised in
#3377.
Inspecting the multiprocessing code, it appears that MapResult is
a minimal extension of AsyncResult, so I choose to remove the extra
List[] type from its generic argument (alternatively one could remove it
from the return type of map_async() itself, but this seems incorrect as
map() has a return type of List[]).
The multiprocessing.pool API appears not to have changed at least since
2.7, so this change should work for both Python 2 and 3.