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multiprocessing.get_all_start_methods() wrong default on macOS #83425

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stefanholek mannequin opened this issue Jan 7, 2020 · 9 comments
Closed

multiprocessing.get_all_start_methods() wrong default on macOS #83425

stefanholek mannequin opened this issue Jan 7, 2020 · 9 comments
Labels
3.8 only security fixes 3.9 only security fixes 3.10 only security fixes easy stdlib Python modules in the Lib dir type-bug An unexpected behavior, bug, or error

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@stefanholek
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stefanholek mannequin commented Jan 7, 2020

BPO 39244
Nosy @pitrou, @taleinat, @applio, @miss-islington, @idomic
PRs
  • bpo-39244: multiprocessing get all start methods #18529
  • bpo-39244: multiprocessing get all start methods #18625
  • [3.9] bpo-39244: multiprocessing return default start method first on macOS (GH-18625) #20431
  • [3.8] bpo-39244: multiprocessing return default start method first on macOS (GH-18625) #20432
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    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 = <Date 2020-05-26.14:56:17.976>
created_at = <Date 2020-01-07.11:54:46.917>
labels = ['easy', 'type-bug', '3.8', '3.9', '3.10', 'library']
title = 'multiprocessing.get_all_start_methods() wrong default on macOS'
updated_at = <Date 2020-05-26.15:14:04.838>
user = 'https://bugs.python.org/stefanholek'

    bugs.python.org fields:

    activity = <Date 2020-05-26.15:14:04.838>
actor = 'miss-islington'
assignee = 'none'
closed = True
closed_date = <Date 2020-05-26.14:56:17.976>
closer = 'taleinat'
components = ['Library (Lib)']
creation = <Date 2020-01-07.11:54:46.917>
creator = 'stefanholek'
dependencies = []
files = []
hgrepos = []
issue_num = 39244
keywords = ['patch', 'newcomer friendly']
message_count = 9.0
messages = ['359503', '362097', '362104', '362517', '369839', '369990', '369992', '369997', '369998']
nosy_count = 6.0
nosy_names = ['pitrou', 'taleinat', 'stefanholek', 'davin', 'miss-islington', 'Ido Michael']
pr_nums = ['18529', '18625', '20431', '20432']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue39244'
versions = ['Python 3.8', 'Python 3.9', 'Python 3.10']
    @stefanholek
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    stefanholek mannequin commented Jan 7, 2020

    In Python 3.8 the default start method has changed from fork to spawn on macOS.
    https://docs.python.org/3/whatsnew/3.8.html#multiprocessing

    get_all_start_methods() says: "Returns a list of the supported start methods, the first of which is the default."
    https://docs.python.org/3/library/multiprocessing.html?highlight=finalize#multiprocessing.get_all_start_methods

    However, it appears to still return fork as default:

      Python 3.8.1 (default, Dec 22 2019, 03:45:23) 
  [Clang 10.0.1 (clang-1001.0.46.4)] on darwin
  Type "help", "copyright", "credits" or "license" for more information.
  >>> import multiprocessing
  >>> multiprocessing.get_all_start_methods()
  ['fork', 'spawn', 'forkserver']
  >>>

    Thank you!

    @stefanholek stefanholek mannequin added OS-mac 3.8 only security fixes stdlib Python modules in the Lib dir type-bug An unexpected behavior, bug, or error labels Jan 7, 2020
    @ned-deily ned-deily added 3.9 only security fixes and removed OS-mac labels Jan 7, 2020
    @taleinat
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    Good catch, Stefen!

    This seems like we forgot to update multiprocessing.get_all_start_methods() when making the change to make "spawn" the default on macOS. I suggest updating it accordingly.

    @idomic
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    idomic mannequin commented Feb 16, 2020

    Fixed the bug to default any macos into 'spawn'
    PR: #62729

    @idomic
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    idomic mannequin commented Feb 23, 2020

    Created a new clean PR #62825

    @idomic
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    idomic mannequin commented May 24, 2020

    Fixed Tal's comments, I took the darwin if check out of the reduction.HAVE_SEND_HANDLE, also fixed the test

    @taleinat taleinat added 3.10 only security fixes labels May 26, 2020
    @taleinat
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    New changeset db098bc by idomic in branch 'master':
    bpo-39244: multiprocessing return default start method first on macOS (GH-18625)
    db098bc

    @taleinat
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    Thanks for fixing this, Ido!

    @miss-islington
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    New changeset 1c88bf8 by Miss Islington (bot) in branch '3.9':
    bpo-39244: multiprocessing return default start method first on macOS (GH-18625)
    1c88bf8

    @miss-islington
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    New changeset 285ff63 by Miss Islington (bot) in branch '3.8':
    bpo-39244: multiprocessing return default start method first on macOS (GH-18625)
    285ff63

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