[issue35424] multiprocessing.Pool: emit ResourceWarning

[STINNER Victor]

New submission from STINNER Victor <vstinner at redhat.com>:

Since 2 years, I'm fixing frequently "dangling thread" and "dangling process" warnings on buildbots. These bugs are really hard to reproduce. They usually require to get access to a specific buildbot, simulate a specific workload, and get the proper timing to get the warning.

I propose to emit a ResourceWarning in multiprocessing.Pool destructor if the pool has not been cleaned properly. I'm not sure in which cases a warning should be emitted.

Attached PR is a WIP implementation.

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components: Tests
messages: 331201
nosy: pablogsal, vstinner
priority: normal
severity: normal
status: open
title: multiprocessing.Pool: emit ResourceWarning
versions: Python 3.8

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue35424>
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