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TSAN race in _waiting_release #123828

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ccotter opened this issue Sep 8, 2024 · 2 comments · May be fixed by #124107
Open

TSAN race in _waiting_release #123828

ccotter opened this issue Sep 8, 2024 · 2 comments · May be fixed by #124107
Labels
extension-modules C modules in the Modules dir topic-subinterpreters type-bug An unexpected behavior, bug, or error

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@ccotter
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ccotter commented Sep 8, 2024 •
edited by bedevere-app bot
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Bug report

Bug description:

A TSAN (gcc-12) build of the latest version of cpython reports a race in the test_send_recv_different_interpreters_and_threads test:

  Read of size 4 at 0x7ffe8d0c9338 by main thread:
    #0 _waiting_finish_releasing Modules/_interpchannelsmodule.c:504 (_interpchannels.cpython-314-x86_64-linux-gnu.so+0x88f4) (BuildId: 233ea3cec8e2d6b4a5322cdab2aa3fcc24ab85f8)
    #1 channel_send_wait Modules/_interpchannelsmodule.c:1852 (_interpchannels.cpython-314-x86_64-linux-gnu.so+0x88f4)
    #2 channelsmod_send Modules/_interpchannelsmodule.c:3096 (_interpchannels.cpython-314-x86_64-linux-gnu.so+0x8dd0) (BuildId: 233ea3cec8e2d6b4a5322cdab2aa3fcc24ab85f8)
    #3 cfunction_call Objects/methodobject.c:540 (python+0x549e55) (BuildId: f667f6a4a823ca3db627f9e7bf3836f7af978c6d)

    #0 _waiting_release Modules/_interpchannelsmodule.c:498 (_interpchannels.cpython-314-x86_64-linux-gnu.so+0x37c7) (BuildId: 233ea3cec8e2d6b4a5322cdab2aa3fcc24ab85f8)
    #1 channel_recv Modules/_interpchannelsmodule.c:1937 (_interpchannels.cpython-314-x86_64-linux-gnu.so+0x863a) (BuildId: 233ea3cec8e2d6b4a5322cdab2aa3fcc24ab85f8)
    #2 channelsmod_recv Modules/_interpchannelsmodule.c:3189 (_interpchannels.cpython-314-x86_64-linux-gnu.so+0x863a)

Indeed,

cpython/Modules/_interpchannelsmodule.c

Line 504 in 8b209fd

while (waiting->status == WAITING_RELEASING) {
spin waits for waiting->status to change state, with

cpython/Modules/_interpchannelsmodule.c

Line 498 in 8b209fd

waiting->status = WAITING_RELEASED;
triggering the spinning thread to exit the spin. Neither happens under a mutex, or with any release-acquire sequencing.

CPython versions tested on:

CPython main branch

Operating systems tested on:

Linux

Linked PRs
@ccotter ccotter added the type-bug An unexpected behavior, bug, or error label Sep 8, 2024
@ZeroIntensity
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cc @ericsnowcurrently

@picnixz picnixz added extension-modules C modules in the Modules dir topic-subinterpreters labels Sep 8, 2024
@n-bes
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n-bes commented Sep 11, 2024 •
edited
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Can confirm, reproduced on Python-3.13.0b4

p.s. summary table

If I remember correctly, this OOM related with this issue

Снимок экрана 2024-08-13 в 11 20 37

Zheaoli added a commit to Zheaoli/cpython that referenced this issue Sep 15, 2024
@Zheaoli
pythongh-123828: fix data raceing for _waiting_release method in _int…
ffee4ed 
…erpchannelsmodule.c

Signed-off-by: Manjusaka <me@manjusaka.me>
@bedevere-app bedevere-app bot linked a pull request Sep 15, 2024 that will close this issue
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Labels
extension-modules C modules in the Modules dir topic-subinterpreters type-bug An unexpected behavior, bug, or error
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Status: Todo
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gh-123828: fix data raceing for _waiting_release method in _interpchannelsmodule.c Zheaoli/cpython
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@ccotter @picnixz @n-bes @ZeroIntensity