python / python/cpython

Deadlock in multiprocessing.pool.Pool on terminate

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3.7 (EOL) stdlib topic-multiprocessing type-bug
Dominant language
Python
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Description

BPO 29759
Nosy @pitrou, @applio

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 = None
created_at = <Date 2017-03-08.17:50:46.188>
labels = ['3.7', 'type-bug', 'library']
title = 'Deadlock in multiprocessing.pool.Pool on terminate'
updated_at = <Date 2020-05-06.13:48:01.640>
user = 'https://bugs.python.org/mapozyan'

bugs.python.org fields:

activity = <Date 2020-05-06.13:48:01.640>
actor = 'ionelmc'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2017-03-08.17:50:46.188>
creator = 'mapozyan'
dependencies = []
files = []
hgrepos = []
issue_num = 29759
keywords = []
message_count = 5.0
messages = ['289248', '289249', '297215', '297733', '297735']
nosy_count = 4.0
nosy_names = ['pitrou', 'ionelmc', 'davin', 'mapozyan']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue29759'
versions = ['Python 2.7', 'Python 3.5', 'Python 3.6', 'Python 3.7']

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start with the multiprocessing.pool.Pool termination path in Python's library implementation and investigate the reported deadlock during terminate. Reproduce the behavior with a focused multiprocessing example, then identify the affected synchronization path. Done means Pool.terminate() completes without deadlocking and the behavior is covered by a regression test.

Written by the indexing model from the issue text.

Assessment

Tech stack
python
Domain
backend, operating-systems
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
25/100

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