from multiprocessing.pool import Pool bug on linux

[859911096]

BPO	26905
Nosy	@MojoVampire
Files	pool.py: a Pool code

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = <Date 2016-05-03.06:26:21.158>
created_at = <Date 2016-05-02.09:48:14.631>
labels = ['type-bug', 'invalid']
title = 'from multiprocessing.pool import Pool bug on linux'
updated_at = <Date 2016-05-03.06:26:21.157>
user = 'https://bugs.python.org/859911096'

bugs.python.org fields:

activity = <Date 2016-05-03.06:26:21.157>
actor = 'SilentGhost'
assignee = 'none'
closed = True
closed_date = <Date 2016-05-03.06:26:21.158>
closer = 'SilentGhost'
components = []
creation = <Date 2016-05-02.09:48:14.631>
creator = '859911096'
dependencies = []
files = ['42680']
hgrepos = []
issue_num = 26905
keywords = []
message_count = 3.0
messages = ['264637', '264638', '264668']
nosy_count = 3.0
nosy_names = ['jnoller', 'sbt', 'josh.r']
pr_nums = []
priority = 'normal'
resolution = 'not a bug'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue26905'
versions = ['Python 2.7']

[859911096]

When my code run on windows,it's right,but on linux,id(q) print same RAM address.

[larryhastings]

This has nothing to do with Argument Clinic, which is an internal tool used in the Python 3.x series.

[MojoVampire]

The Queue module (queue on Py3) is for communication between threads, not processes; what you've written wouldn't behave correctly on any version of Python. You want to use multiprocessing's Queue class, not Queue.Queue, and to avoid possible deadlocks, you want to populate it after the pool workers are running.

In any event, id(q) is expected to match on Linux, which has fork semantics (so the memory space in parent and child is initially identical). On Windows it differs because spawn based multiprocessing means the objects are recreated in the child processes, rather than inherited directly.

This is a problem with your code and understanding on forking, not a problem in Python.