RFR: 8272480: Remove Mutex::access rank
coleenp at openjdk.java.net
Thu Aug 26 19:52:52 UTC 2021
On Wed, 25 Aug 2021 18:46:32 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:
> This change removes the 'access' rank since the last oop access lock has been removed (Shared_DirtyCardQ_lock). It might make sense to have a very low level access lock for oops but it should be added along with locks that might be introduced at that time, so that the rank is in the right place.
> With this I moved tty back down in the rank hierarchy and added stackwatermark ranks. The latter is above tty, not below, and other locks like Service_lock are taken while holding the stackwatermark lock. There's one tty-1 ranked lock that is actually taken while the tty lock is held.
> I moved MonitorDeflation_lock back to special rank because its low level was just copied from Service_lock, but that's not needed.
> With this I removed most of the out-of-date comment above the rank enum. New comment to follow in future RFE.
> Tested with tier1-6.
# Internal Error (/scratch/coleen/hg/jdk/open/src/hotspot/share/runtime/mutex.cpp:410), pid=27405, tid=27408
# assert(false) failed: Attempting to acquire lock StackWatermark_lock/9 out of order with lock tty_lock/3 -- possible
ttyLock is held during stack walking for -XX:+PrintDeoptimizationDetails -XX:+UseZGC, so put the locks back.
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