python / python/cpython

multiprocessing.pool.Pool.apply block infinitely when stressed while using maxtasksperchild

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

BPO 47159
Nosy @pitrou, @applio, @harsh8398
Files
  • example.py: Example python script which produces the issue
  • 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 2022-03-30.09:53:14.324>
    labels = ['3.7', 'type-bug', 'library']
    title = 'multiprocessing.pool.Pool.apply block infinitely when stressed while using maxtasksperchild'
    updated_at = <Date 2022-03-30.09:53:14.324>
    user = 'https://github.com/harsh8398'
    

    bugs.python.org fields:

    activity = <Date 2022-03-30.09:53:14.324>
    actor = 'harsh8398'
    assignee = 'none'
    closed = False
    closed_date = None
    closer = None
    components = ['Library (Lib)']
    creation = <Date 2022-03-30.09:53:14.324>
    creator = 'harsh8398'
    dependencies = []
    files = ['50706']
    hgrepos = []
    issue_num = 47159
    keywords = []
    message_count = 1.0
    messages = ['416331']
    nosy_count = 3.0
    nosy_names = ['pitrou', 'davin', 'harsh8398']
    pr_nums = []
    priority = 'normal'
    resolution = None
    stage = None
    status = 'open'
    superseder = None
    type = 'behavior'
    url = 'https://bugs.python.org/issue47159'
    versions = ['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 by running the attached example.py while stressing multiprocessing.pool.Pool.apply with maxtasksperchild, then inspect the relevant multiprocessing pool behavior. Done means the reproducer no longer blocks indefinitely under those conditions, with a regression check added where appropriate.

    Written by the indexing model from the issue text.

    Assessment

    Tech stack
    python
    Domain
    backend
    Issue type
    Bug
    Difficulty
    4/5
    Estimated time
    3-5 days
    Activity status
    Stale
    Clarity
    Mostly clear
    Newbie friendliness
    25/100

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