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deadlocked child process after forking on pystate.c's HEAD_LOCK #112275
Description
Activity
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?
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.
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.
- added a commit that references this issue
on Sep 4, 2024 Thanks a lot!
- added a commit that references this issue
on Sep 5, 2024 Thank you for the report and patch!
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