python / python/cpython

multiprocessing.Condition.notify_all() blocks indefinitely if a process waiting on it has died

Open
#75,158 4 comments 0 reactions 0 assignees View on GitHub

Nobody has claimed this yet.

3.7 (EOL) OS-windows topic-multiprocessing type-bug
Dominant language
Python
Stars
77.2k
Forks
36k
PR merge metrics
PR metrics pending

Description

BPO 30975
Nosy @pfmoore, @pitrou, @tjguk, @zware, @zooba, @applio, @mickp
Files
  • WaitersSleepers.py: A script to demonstrate to the issue.
  • WaitersSleepers.py
  • Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.

    Show more details

    GitHub fields:

    assignee = None
    closed_at = None
    created_at = <Date 2017-07-20.11:29:48.884>
    labels = ['type-bug', '3.7', 'OS-windows']
    title = 'multiprocessing.Condition.notify_all() blocks indefinitely if a process waiting on it has died'
    updated_at = <Date 2017-07-20.14:20:00.088>
    user = 'https://github.com/mickp'
    

    bugs.python.org fields:

    activity = <Date 2017-07-20.14:20:00.088>
    actor = 'pitrou'
    assignee = 'none'
    closed = False
    closed_date = None
    closer = None
    components = ['Windows']
    creation = <Date 2017-07-20.11:29:48.884>
    creator = 'mickp'
    dependencies = []
    files = ['47025', '47027']
    hgrepos = []
    issue_num = 30975
    keywords = []
    message_count = 4.0
    messages = ['298713', '298719', '298720', '298722']
    nosy_count = 8.0
    nosy_names = ['paul.moore', 'pitrou', 'tim.golden', 'sbt', 'zach.ware', 'steve.dower', 'davin', 'mickp']
    pr_nums = []
    priority = 'normal'
    resolution = None
    stage = 'needs patch'
    status = 'open'
    superseder = None
    type = 'behavior'
    url = 'https://bugs.python.org/issue30975'
    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 by running the attached WaitersSleepers.py reproducer and compare the two uploaded versions, WaitersSleepers.py files 47025 and 47027. Trace the Windows multiprocessing.Condition behavior when a waiting process exits, then verify that notify_all() returns rather than blocking indefinitely in that scenario.

    Written by the indexing model from the issue text.

    Assessment

    Tech stack
    python
    Domain
    operating-systems
    Issue type
    Bug
    Difficulty
    4/5
    Estimated time
    3-5 days
    Activity status
    Stale
    Clarity
    Mostly clear
    Newbie friendliness
    35/100

    Get new issues in your inbox

    A short digest of beginner-friendly GitHub issues.