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Add optional argument to Semaphore.release for releasing multiple threads #55187

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rhettinger opened this issue Jan 22, 2011 · 6 comments
Closed

Add optional argument to Semaphore.release for releasing multiple threads #55187

rhettinger opened this issue Jan 22, 2011 · 6 comments
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@rhettinger
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3.9 only security fixes stdlib Python modules in the Lib dir type-feature A feature request or enhancement

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@rhettinger
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BPO 10978
Nosy @tim-one, @rhettinger, @pitrou, @MojoVampire
PRs
  • bpo-10978: Semaphores can release multiple threads at a time #15588
    		•
    Files
  • sem.diff: Patch to threading.py
  • multirelease.diff: Update patch to Py3.5. Add test and docs
    		•

    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 = 'https://github.com/rhettinger'
closed_at = <Date 2019-08-29.08:45:42.904>
created_at = <Date 2011-01-22.00:15:34.025>
labels = ['type-feature', 'library', '3.9']
title = 'Add optional argument to Semaphore.release for releasing multiple threads'
updated_at = <Date 2019-08-29.08:45:42.904>
user = 'https://github.com/rhettinger'

    bugs.python.org fields:

    activity = <Date 2019-08-29.08:45:42.904>
actor = 'rhettinger'
assignee = 'rhettinger'
closed = True
closed_date = <Date 2019-08-29.08:45:42.904>
closer = 'rhettinger'
components = ['Library (Lib)']
creation = <Date 2011-01-22.00:15:34.025>
creator = 'rhettinger'
dependencies = []
files = ['20483', '35718']
hgrepos = []
issue_num = 10978
keywords = ['patch']
message_count = 6.0
messages = ['126804', '135005', '221028', '221213', '221585', '350757']
nosy_count = 5.0
nosy_names = ['tim.peters', 'rhettinger', 'pitrou', 'neologix', 'josh.r']
pr_nums = ['15588']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue10978'
versions = ['Python 3.9']
    @rhettinger
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    Call sem.release(5) would have the same effect as:

    with lock:
    for i in range(5):
         sem.release()

    The use case is when a single semaphore is holding up multiple threads and needs to release them all. According to "The Little Book of Semaphores <http://greenteapress.com/semaphores/\>", this is a common design pattern.

    Basic patch attached. If the proposal meets with acceptance, will add tests and a doc update.

    @rhettinger rhettinger added type-bug An unexpected behavior, bug, or error stdlib Python modules in the Lib dir labels Jan 22, 2011
    @rhettinger rhettinger self-assigned this Mar 23, 2011
    @pitrou
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    pitrou commented May 2, 2011

    Your patch uses tabs for indentation. Otherwise, looks good on the principle.

    @pitrou pitrou added type-feature A feature request or enhancement and removed type-bug An unexpected behavior, bug, or error labels May 2, 2011
    @BreamoreBoy
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    BreamoreBoy mannequin commented Jun 19, 2014

    Seems good to proceed as there are no dissenters.

    @rhettinger
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    Updated patch (with tests and docs).

    @MojoVampire
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    MojoVampire mannequin commented Jun 25, 2014

    Never know whether to comment on issue itself, but just in case:

    There are issues with the patch when n < 0 is passed, as n is not sanity checked, which would break the Semaphore invariant (value must be >= 0). n == 0 is also a weird value, but harmless if passed; release(0) would acquire and release the lock but otherwise act as a noop.

    @rhettinger rhettinger added the 3.9 only security fixes label Aug 29, 2019
    @rhettinger
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    New changeset 35f6301 by Raymond Hettinger in branch 'master':
    bpo-10978: Semaphores can release multiple threads at a time (GH-15588)
    35f6301

    @ezio-melotti ezio-melotti transferred this issue from another repository Apr 10, 2022
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