Fix deadlock in multithreaded fork in OS X.#1
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petermattis merged 1 commit intocrl-release-4.5.0from Mar 17, 2019
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On OS X, we rely on the zone machinery to call our prefork and postfork handlers. In zone_force_unlock, we call jemalloc_postfork_child, reinitializing all our mutexes regardless of state, since the mutex implementation will assert if the tid of the unlocker is different from that of the locker. This has the effect of unlocking the mutexes, but also fails to wake any threads waiting on them in the parent. To fix this, we track whether or not we're the parent or child after the fork, and unlock or reinit as appropriate. This resolves jemalloc#895.
Author
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I haven't been able to reproduce the lock up when running on top of this patch. Seems safer to back port this patch, than to try and upgrade jemalloc. Note that affected code only runs on Darwin. |
Member
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LGTM |
bdarnell
approved these changes
Mar 16, 2019
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On OS X, we rely on the zone machinery to call our prefork and postfork
handlers.
In zone_force_unlock, we call jemalloc_postfork_child, reinitializing all our
mutexes regardless of state, since the mutex implementation will assert if the
tid of the unlocker is different from that of the locker. This has the effect
of unlocking the mutexes, but also fails to wake any threads waiting on them in
the parent.
To fix this, we track whether or not we're the parent or child after the fork,
and unlock or reinit as appropriate.
This resolves jemalloc#895.