RFR: 8311218: fatal error: stuck in JvmtiVTMSTransitionDisabler::VTMS_transition_disable [v5]
Serguei Spitsyn
sspitsyn at openjdk.org
Thu Dec 14 18:26:55 UTC 2023
> 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 notifyJvmtiDisableSuspend(true) out of try-block
-------------
Changes:
- all: https://git.openjdk.org/jdk/pull/17011/files
- new: https://git.openjdk.org/jdk/pull/17011/files/4e5f6447..ad990422
Webrevs:
- full: https://webrevs.openjdk.org/?repo=jdk&pr=17011&range=04
- incr: https://webrevs.openjdk.org/?repo=jdk&pr=17011&range=03-04
Stats: 10 lines in 1 file changed: 5 ins; 5 del; 0 mod
Patch: https://git.openjdk.org/jdk/pull/17011.diff
Fetch: git fetch https://git.openjdk.org/jdk.git pull/17011/head:pull/17011
PR: https://git.openjdk.org/jdk/pull/17011
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