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current_thread() becomes "dummy" thread during shutdown #75697

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pitrou opened this issue Sep 19, 2017 · 10 comments
Closed

current_thread() becomes "dummy" thread during shutdown #75697

pitrou opened this issue Sep 19, 2017 · 10 comments
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3.7 (EOL) end of life stdlib Python modules in the Lib dir type-bug An unexpected behavior, bug, or error

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@pitrou
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pitrou commented Sep 19, 2017

BPO 31516
Nosy @tim-one, @pitrou, @vstinner, @asvetlov, @serhiy-storchaka, @miss-islington
PRs
  • bpo-31516: current_thread() should not return a dummy thread at shutdown #3673
  • [3.6] bpo-31516: current_thread() should not return a dummy thread at shutdown (GH-3673) #3856
  • bpo-31516: Skip test_main_thread_during_shutdown() with COUNT_ALLOCS builds #8052
  • [3.7] bpo-31516: Skip test_main_thread_during_shutdown() with COUNT_ALLOCS builds. (GH-8052) #9813
  • [3.6] bpo-31516: Skip test_main_thread_during_shutdown() with COUNT_ALLOCS builds. (GH-8052) #9814
    		•
    Files
  • mainthread.py
    		•

    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 2017-10-02.15:20:39.908>
created_at = <Date 2017-09-19.11:33:54.534>
labels = ['3.7', 'type-bug', 'library']
title = 'current_thread() becomes "dummy" thread during shutdown'
updated_at = <Date 2018-10-12.08:54:24.047>
user = 'https://github.com/pitrou'

    bugs.python.org fields:

    activity = <Date 2018-10-12.08:54:24.047>
actor = 'miss-islington'
assignee = 'none'
closed = True
closed_date = <Date 2017-10-02.15:20:39.908>
closer = 'pitrou'
components = ['Library (Lib)']
creation = <Date 2017-09-19.11:33:54.534>
creator = 'pitrou'
dependencies = []
files = ['47152']
hgrepos = []
issue_num = 31516
keywords = ['patch']
message_count = 10.0
messages = ['302515', '302517', '302637', '302641', '303537', '303542', '303543', '327572', '327573', '327575']
nosy_count = 6.0
nosy_names = ['tim.peters', 'pitrou', 'vstinner', 'asvetlov', 'serhiy.storchaka', 'miss-islington']
pr_nums = ['3673', '3856', '8052', '9813', '9814']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue31516'
versions = ['Python 3.6', 'Python 3.7']
    @pitrou
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    pitrou commented Sep 19, 2017

    Attaching reproducer. During interpreter shutdown, threading.main_thread() gets marked "stopped" (while it's obviously still running), while threading.current_thread() returns a DummyThread instance with the same ident as the main thread.

    $ ./python mainthread.py 
-- before shutdown --
GC in thread <_MainThread(MainThread, started 140359122872064)>
main thread is <_MainThread(MainThread, started 140359122872064)>
-- during shutdown --
GC in thread <_DummyThread(Dummy-1, started daemon 140359122872064)>
main thread is <_MainThread(MainThread, stopped 140359122872064)>

    @pitrou pitrou added 3.7 (EOL) end of life stdlib Python modules in the Lib dir type-bug An unexpected behavior, bug, or error labels Sep 19, 2017
    @pitrou
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    pitrou commented Sep 19, 2017

    The main thread being marked "stopped" at shutdown might be an obscure feature (as hinted in the comments for threading._shutdown()). However, current_thread() should definitely not return a separate DummyThread instance.

    @pitrou
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    pitrou commented Sep 20, 2017

    Tim, any opinion on this one? Do you agree it's an actual bug (if a bit obscure)?

    @tim-one
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    tim-one commented Sep 20, 2017

    Ya, it's clearly best for current_thread() to deliver consistent results.

    @pitrou
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    pitrou commented Oct 2, 2017

    New changeset 1023dbb by Antoine Pitrou in branch 'master':
    bpo-31516: current_thread() should not return a dummy thread at shutdown (bpo-3673)
    1023dbb

    @pitrou
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    pitrou commented Oct 2, 2017

    New changeset ac6245a by Antoine Pitrou (Miss Islington (bot)) in branch '3.6':
    [3.6] bpo-31516: current_thread() should not return a dummy thread at shutdown (GH-3673) (bpo-3856)
    ac6245a

    @pitrou
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    pitrou commented Oct 2, 2017

    I have now pushed the fix to master and 3.6. Hopefully this won't break anyone's code...

    @pitrou pitrou closed this as completed Oct 2, 2017
    @serhiy-storchaka
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    New changeset 65d2f8c by Serhiy Storchaka (Zackery Spytz) in branch 'master':
    bpo-31516: Skip test_main_thread_during_shutdown() with COUNT_ALLOCS builds. (GH-8052)
    65d2f8c

    @miss-islington
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    New changeset c327a54 by Miss Islington (bot) in branch '3.7':
    bpo-31516: Skip test_main_thread_during_shutdown() with COUNT_ALLOCS builds. (GH-8052)
    c327a54

    @miss-islington
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    New changeset d918e98 by Miss Islington (bot) in branch '3.6':
    bpo-31516: Skip test_main_thread_during_shutdown() with COUNT_ALLOCS builds. (GH-8052)
    d918e98

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