JVMTI VThreadMonitorTest fails with an unexpected monitor

[dipak-bagadiya]

Issue

The JVMTI VThreadMonitorTest fails with an unexpected monitor from GetCurrentContendedMonitor for a virtual thread.

Test CMD

make test TEST="jtreg:test/hotspot/jtreg/serviceability/jvmti/vthread/VThreadMonitorTest" JTREG="JAVA_OPTIONS=--enable-preview -Dvm.continuations=true;VERBOSE=all"

Test Output:

checkContendedMonitor: VirtualThread-0: contended monitor: (nil)
FAIL: is_vt: 1: unexpected monitor from GetCurrentContendedMonitor
stack trace of current thread:
JVMTI Stack Trace for thread MainThread: frame count: 10
 0: VThreadMonitorTest: checkContendedMonitor(Ljava/lang/Thread;Ljava/lang/Object;Ljava/lang/Object;)V
 1: VThreadMonitorTest: main([Ljava/lang/String;)V
 2: java/lang/invoke/LambdaForm$DMH.0x000000004c014bf0: invokeStatic(Ljava/lang/Object;Ljava/lang/Object;)V
 3: java/lang/invoke/LambdaForm$MH.0x000000004c018a10: invoke(Ljava/lang/Object;Ljava/lang/Object;Ljava/lang/Object;)Ljava/lang/Object;
 4: java/lang/invoke/LambdaForm$MH.0x000000004c019790: invokeExact_MT(Ljava/lang/Object;Ljava/lang/Object;Ljava/lang/Object;Ljava/lang/Object;)Ljava/lang/Object;
 5: jdk/internal/reflect/DirectMethodHandleAccessor: invokeImpl(Ljava/lang/Object;[Ljava/lang/Object;)Ljava/lang/Object;
 6: jdk/internal/reflect/DirectMethodHandleAccessor: invoke(Ljava/lang/Object;[Ljava/lang/Object;)Ljava/lang/Object;
 7: java/lang/reflect/Method: invoke(Ljava/lang/Object;[Ljava/lang/Object;)Ljava/lang/Object;
 8: com/sun/javatest/regtest/agent/MainWrapper$MainThread: run()V
 9: java/lang/Thread: run()V


java.lang.RuntimeException: FAILED status returned from the agent
        at VThreadMonitorTest.main(VThreadMonitorTest.java:142)
        at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104)
        at java.base/java.lang.reflect.Method.invoke(Method.java:578)
        at com.sun.javatest.regtest.agent.MainWrapper$MainThread.run(MainWrapper.java:125)
        at java.base/java.lang.Thread.run(Thread.java:1573)
JavaTest Message: Test threw exception: java.lang.RuntimeException: FAILED status returned from the agent
JavaTest Message: shutting down test

[fengxue-IS]

@thallium can you take a look at this

[thallium]

In libVThreadMonitorTest.cpp:97 we are expecting the contended monitor to be either lock0 or lock2 but we are getting a null object.

[thallium]

The test also failed for platform thread. We should check the way of triggering contention to see if this is against the spec.

[thallium]

Currently in our code the JVMTI Monitor Contended Enter is triggered before setting the thread flag. When the JVMTI event is triggered, the contended monitor check is then triggered, but at that time we haven't set the flag so we couldn't get the correct monitor object. I've proposed a fix #16844 to set the flag before triggering the event.

[babsingh]

@thallium Two more tasks before we can close this issue:

• The test needs to be re-enabled for JDK19 and JDK20; currently, it is disabled; and
• The fix will also need to be backported to the 0.37 and 0.38 release branches since it impacts all Java versions.

fyi @fengxue-IS @JasonFengJ9 @tajila

[thallium]

@thallium Two more tasks before we can close this issue:

• The test needs to be re-enabled for JDK19 and JDK20; currently, it is disabled; and
• The fix will also need to be backported to the 0.37 and 0.38 release branches since it impacts all Java versions.

fyi @fengxue-IS @JasonFengJ9 @tajila

Done, see #16895 and adoptium/aqa-tests#4420

[babsingh]

@thallium Thanks. Closing as per #16685 (comment).