Add assertions for incompatible vthread states

Adding assertions to verify virtual thread behaviour is valid. The
expectation is that instead of hangs we will see assertion failures
which will aid in the investigation of issues.

Signed-off-by: Tobi Ajila <[email protected]>

Author: tajila

runtime/vm/ContinuationHelpers.cpp

@@ -798,6 +798,7 @@ void
 updateMonitorInfo(J9VMThread *currentThread, J9ObjectMonitor *objectMonitor)
 {
 	J9ThreadAbstractMonitor *monitor = (J9ThreadAbstractMonitor *)objectMonitor->monitor;
+	Assert_VM_true(1 == (UDATA)monitor->owner);
 	monitor->owner = currentThread->osThread;
 	objectMonitor->ownerContinuation = NULL;
 }
@@ -937,6 +938,8 @@ preparePinnedVirtualThreadForUnmount(J9VMThread *currentThread, j9object_t syncO
 			syncObjectMonitor = J9_INFLLOCK_OBJECT_MONITOR(lock);
 		} else {
 			if (isObjectWait) {
+				/* Current thread must own at least one monitor if wait was called. */
+				Assert_VM_true(currentThread->ownedMonitorCount > 0);
 				syncObjectMonitor = objectMonitorInflate(currentThread, syncObj, lock);
 				if (NULL == syncObjectMonitor) {
 					result = J9_OBJECT_MONITOR_OOM;
@@ -1074,11 +1077,11 @@ preparePinnedVirtualThreadForUnmount(J9VMThread *currentThread, j9object_t syncO
 
 	if (NULL != syncObj) {
 		j9object_t continuationObj = J9VMJAVALANGVIRTUALTHREAD_CONT(currentThread, currentThread->threadObject);
+		omrthread_monitor_t monitor = syncObjectMonitor->monitor;
 		J9VMJDKINTERNALVMCONTINUATION_SET_BLOCKER(currentThread, continuationObj, syncObj);
 
 		if (isObjectWait) {
 			J9VMContinuation *continuation = currentThread->currentContinuation;
-			omrthread_monitor_t monitor = syncObjectMonitor->monitor;
 
 			/* Record wait monitor state. */
 			continuation->waitingMonitorEnterCount = monitor->count;
@@ -1100,6 +1103,11 @@ preparePinnedVirtualThreadForUnmount(J9VMThread *currentThread, j9object_t syncO
 			/* Increment the wait count on inflated monitor. */
 			VM_AtomicSupport::addU32(&syncObjectMonitor->virtualThreadWaitCount, 1);
 			currentThread->currentContinuation->objectWaitMonitor = syncObjectMonitor;
+
+			if (NULL != monitor) {
+				/* If we are blocking to wait on a contended monitor then we can't be the owner. */
+				//Assert_VM_false(monitor->owner == currentThread->osThread);
+			}
 		}
 	}
 

runtime/vm/ObjectMonitor.cpp

@@ -493,6 +493,9 @@ objectMonitorEnterNonBlocking(J9VMThread *currentThread, j9object_t object)
 				} else {
 					/* the monitor is already inflated */
 					objectMonitor = J9_INFLLOCK_OBJECT_MONITOR(lock);
+
+					/* Monitor must be owned by valid thread */
+					Assert_VM_true(1 != objectMonitor->monitor->owner);
 				}
 				if (!spinOnTryEnter(currentThread, objectMonitor, lwEA, object)) {
 					goto wouldBlock;