RFR: 8297286: runtime/vthread tests crashing after JDK-8296324

[Leonid Mesnik]

On Wed, 23 Nov 2022 00:24:28 GMT, Serguei Spitsyn <sspitsyn at openjdk.org> wrote:

> This problem has two sides.
> One is that the `VirtualThread::run() `cashes the field `notifyJvmtiEvents` value.
> It caused the native method `notifyJvmtiUnmountBegin()` not called after the field `notifyJvmtiEvents`
> value has been set to `true` when an agent library is loaded into running VM.
> The fix is to get rid of this cashing.
> Another is that enabling `notifyJvmtiEvents` notifications needs a synchronization.
> Otherwise, a VTMS transition start can be missed which will cause some asserts to fire.
> The fix is to use a JvmtiVTMSTransitionDisabler helper for sync.
> 
> Testing:
> The originally failed tests are passed now:
> 
> runtime/vthread/RedefineClass.java
> runtime/vthread/TestObjectAllocationSampleEvent.java 
> 
> In progress:
> Run the tiers 1-6 to make sure there are no regression.

Marked as reviewed by lmesnik (Reviewer).

src/java.base/share/classes/java/lang/VirtualThread.java line 273:

> 271:     private void run(Runnable task) {
> 272:         assert state == RUNNING;
> 273:         boolean notifyJvmti = notifyJvmtiEvents;

Don't we have same issue in yieldContinuation() method? (line 396)

-------------

PR: https://git.openjdk.org/jdk/pull/11304