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deadlocked child process after forking on pystate.c's HEAD_LOCK #112275

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ChuBoning opened this issue Nov 20, 2023 · 3 comments
Open

deadlocked child process after forking on pystate.c's HEAD_LOCK #112275

ChuBoning opened this issue Nov 20, 2023 · 3 comments
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3.11 bug and security fixes interpreter-core (Objects, Python, Grammar, and Parser dirs) pending The issue will be closed if no feedback is provided topic-multiprocessing type-bug An unexpected behavior, bug, or error

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@ChuBoning
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ChuBoning commented Nov 20, 2023 •
edited by bedevere-app bot

Bug report

Bug description:

A forked process (via os.fork) can inherit a locked runtime->interpreters.mutex from its parent process and will deadlock in this stack:
Child Process (deadlocked):
#0 0x0000ffffa9b2b268 in do_futex_wait.constprop () from /lib/aarch64-linux-gnu/libpthread.so.0
#1 0x0000ffffa9b2b39c in __new_sem_wait_slow.constprop.0 () from /lib/aarch64-linux-gnu/libpthread.so.0
#2 0x0000ffffa9e96eb8 in PyThread_acquire_lock_timed () from /usr/local/lib/libpython3.8.so.1.0
#3 0x0000ffffa9e865a8 in _PyThreadState_DeleteExcept () from /usr/local/lib/libpython3.8.so.1.0
#4 0x0000ffffa9eb94ac in PyOS_AfterFork_Child () from /usr/local/lib/libpython3.8.so.1.0

Similar to #74580 and it's solved by f82c951 on python3.6 and 3.7

However,the problem appeares again on python3.8: HEAD_LOCK is called from PyOS_AfterFork_Child->_PyEval_ReInitThreads->_PyThreadState_DeleteExcept before PyOS_AfterFork_Child->_PyRuntimeState_ReInitThreads reinit runtime->interpreters.mutex.

I notice the problem will be resolved on python3.12 from the source code,but is it still existed on python3.8 to 3.11?

CPython versions tested on:

3.8

Operating systems tested on:

Linux

Linked PRs
@ChuBoning ChuBoning added the type-bug An unexpected behavior, bug, or error label Nov 20, 2023
@arhadthedev arhadthedev added interpreter-core (Objects, Python, Grammar, and Parser dirs) topic-multiprocessing 3.11 bug and security fixes labels Nov 20, 2023
@itamaro
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itamaro commented Nov 20, 2023

Python 3.8 is receiving only security fixes currently (so is 3.9 and 3.10).

Could you check whether this issue reproduces with 3.11 and/or 3.12 and update the issue accordingly?

@itamaro itamaro added the pending The issue will be closed if no feedback is provided label Nov 20, 2023
@ChuBoning
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Python 3.8 is receiving only security fixes currently (so is 3.9 and 3.10).

Could you check whether this issue reproduces with 3.11 and/or 3.12 and update the issue accordingly?

I haven't tried it on 3.11 yet.But I think this issue will reproduce on 3.11. And there is no such issue on 3.12 since _PyRuntimeState_ReInitThreads calls _PyThread_at_fork_reinit to reinit the lock at the beginning.

@bedevere-app bedevere-app bot mentioned this issue Nov 23, 2023
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@ChuBoning
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Python 3.8 is receiving only security fixes currently (so is 3.9 and 3.10).

Could you check whether this issue reproduces with 3.11 and/or 3.12 and update the issue accordingly?

Could you please take a look at this #112336 ? I fix it just as python3.12 does.

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@itamaro @arhadthedev @ChuBoning