Merge pull request #20649 from tajila/jfr2

(0.49) Recent JFR fixes

jcl/src/java.base/share/classes/java/lang/System.java

@@ -736,7 +736,10 @@ private static void ensureProperties(boolean isInitialization) {
 	/*[ENDIF] CRIU_SUPPORT */
 
 	/*[IF JFR_SUPPORT]*/
+	/* Enables openj9 JFR tests. */
 	initializedProperties.put("org.eclipse.openj9.jfr.isJFREnabled", "true"); //$NON-NLS-1$ //$NON-NLS-2$
+	/* TODO disable JFR JCL APIs until JFR natives are implemented. */
+	initializedProperties.put("jfr.unsupported.vm", "true"); //$NON-NLS-1$ //$NON-NLS-2$
 	/*[ENDIF] JFR_SUPPORT */
 
 	String[] list = getPropertyList();

runtime/vm/JFRConstantPoolTypes.cpp

@@ -853,6 +853,15 @@ VM_JFRConstantPoolTypes::addThreadGroupEntry(j9object_t threadGroup)
 	entry->parentIndex = addThreadGroupEntry(J9VMJAVALANGTHREADGROUP_PARENT(_currentThread, threadGroup));
 	if (isResultNotOKay()) goto done;
 
+	/* Check again to see if the Threadgroup was added recursively. */
+	entry = (ThreadGroupEntry *) hashTableFind(_threadGroupTable, entry);
+	if (NULL != entry) {
+		index = entry->index;
+		goto done;
+	} else {
+		entry = &entryBuffer;
+	}
+
 	entry->name = copyStringToJ9UTF8WithMemAlloc(_currentThread, J9VMJAVALANGTHREADGROUP_NAME(_currentThread, threadGroup), J9_STR_NONE, "", 0, NULL, 0);
 
 	entry->index = _threadGroupCount;

runtime/vm/jfr.cpp

@@ -979,9 +979,11 @@ jfrSamplingThreadProc(void *entryArg)
 		while (J9JFR_SAMPLER_STATE_STOP != vm->jfrSamplerState) {
 			J9SignalAsyncEvent(vm, NULL, vm->jfrAsyncKey);
 			if (0 == (count % 100)) { // 1 second
+				omrthread_monitor_exit(vm->jfrSamplerMutex);
 				internalAcquireVMAccess(currentThread);
 				jfrCPULoad(currentThread);
 				internalReleaseVMAccess(currentThread);
+				omrthread_monitor_enter(vm->jfrSamplerMutex);
 				if (0 == (count % 1000)) { // 10 seconds
 					J9SignalAsyncEvent(vm, NULL, vm->jfrThreadCPULoadAsyncKey);
 				}