[New-bugs-announce] [issue29108] Python 3.6.0 multiprocessing map_async callback

[Jose Miguel Colella]

New submission from Jose Miguel Colella:

Hello I am trying to use the callback for the map_async method for Pool, but have found a bug. In the below code, only the print statement is carried out, the return is completely ignored. Is this working as designed or is this a bug?

from multiprocessing import Pool


def f(x):
    return x * x


def s(x):
    print(f'Here: {x}')
    return type(x)


if __name__ == '__main__':
    with Pool(5) as p:
        result = p.map_async(f, [1, 2, 3], callback=s)
        q = result.get()
        print(q)

----------
components: Library (Lib)
files: main2.py
messages: 284295
nosy: Jose Miguel Colella
priority: normal
severity: normal
status: open
title: Python 3.6.0 multiprocessing map_async callback
type: behavior
versions: Python 3.6
Added file: http://bugs.python.org/file46084/main2.py

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue29108>
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