python / python/cpython

concurrent.futures.ProcessPoolExecutor freezes depending on complexity

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3.7 (EOL) OS-mac topic-multiprocessing
Dominant language
Python
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Description

BPO 42245
Nosy @brianquinlan, @ronaldoussoren, @pitrou, @ned-deily, @Fidget-Spinner, @Danil Zherebtsov
Files
  • concur_fut_freeze.py: code to reproduce.
  • 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 2020-11-02.13:33:55.337>
    labels = ['OS-mac', '3.7']
    title = 'concurrent.futures.ProcessPoolExecutor freezes depending on complexity'
    updated_at = <Date 2020-11-19.15:43:32.534>
    user = 'https://github.com/DanilZherebtsov'
    

    bugs.python.org fields:

    activity = <Date 2020-11-19.15:43:32.534>
    actor = 'ronaldoussoren'
    assignee = 'none'
    closed = False
    closed_date = None
    closer = None
    components = ['macOS']
    creation = <Date 2020-11-02.13:33:55.337>
    creator = 'DanilZ'
    dependencies = []
    files = ['49562']
    hgrepos = []
    issue_num = 42245
    keywords = []
    message_count = 13.0
    messages = ['380220', '380225', '380228', '380229', '380233', '380236', '380240', '380764', '380766', '380768', '380793', '381414', '381438']
    nosy_count = 6.0
    nosy_names = ['bquinlan', 'ronaldoussoren', 'pitrou', 'ned.deily', 'kj', 'DanilZ']
    pr_nums = []
    priority = 'normal'
    resolution = None
    stage = None
    status = 'open'
    superseder = None
    type = None
    url = 'https://bugs.python.org/issue42245'
    versions = ['Python 3.7']
    

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    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 concur_fut_freeze.py reproducer on macOS with the reported Python 3.7 context, then trace the ProcessPoolExecutor path involved in the freeze. Done means the reported complexity-dependent freezing is resolved and the reproducer’s cases are covered by regression testing.

    Written by the indexing model from the issue text.

    Assessment

    Tech stack
    python
    Domain
    backend, distributed-systems
    Issue type
    Bug
    Difficulty
    4/5
    Estimated time
    3-5 days
    Activity status
    Stale
    Clarity
    Needs clarification
    Newbie friendliness
    30/100

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