On Thu, 14 Dec 2023 22:57:53 GMT, Serguei Spitsyn <sspit...@openjdk.org> wrote:
>> This fix is for JDK 23 but the intention is to back port it to 22 in RDP-1 >> time frame. >> It is fixing a deadlock issue between `VirtualThread` class critical >> sections with the `interruptLock` (in methods: `unpark()`, `interrupt()`, >> `getAndClearInterrupt()`, `threadState()`, `toString()`), >> `JvmtiVTMSTransitionDisabler` and JVMTI `Suspend/Resume` mechanisms. >> The deadlocking scenario is well described by Patricio in a bug report >> comment. >> In simple words, a virtual thread should not be suspended during >> 'interruptLock' critical sections. >> >> The fix is to record that a virtual thread is in a critical section >> (`JavaThread`'s `_in_critical_section` bit) by notifying the VM/JVMTI about >> begin/end of critical section. >> This bit is used in `HandshakeState::get_op_for_self()` to filter out any >> `HandshakeOperation` if a target `JavaThread` is in a critical section. >> >> Some of new notifications with `notifyJvmtiSync()` method is on a >> performance critical path. It is why this method has been intrincified. >> >> New test was developed by Patricio: >> `test/hotspot/jtreg/serviceability/jvmti/vthread/SuspendWithInterruptLock` >> The test is very nice as it reliably in 100% reproduces the deadlock without >> the fix. >> The test is never failing with this fix. >> >> Testing: >> - tested with newly added test: >> `test/hotspot/jtreg/serviceability/jvmti/vthread/SuspendWithInterruptLock` >> - tested with mach5 tiers 1-6 > > Serguei Spitsyn has updated the pull request incrementally with one > additional commit since the last revision: > > review: moved a couple of comments out of try blocks src/hotspot/share/prims/jvm.cpp line 4019: > 4017: return; > 4018: } > 4019: assert(thread->is_disable_suspend() != (bool)enter, "recursive > disable suspend is not allowed"); This is an important assert, the message should probably say nested or unbalanced enter/exit not allowed. ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/17011#discussion_r1427719197
