8332923: ObjectMonitorUsage.java failed with unexpected waiter_count

Co-authored-by: Jiawei Tang <jwtang@openjdk.org>
Reviewed-by: sspitsyn, alanb, amitkumar

Author: 2 people

src/hotspot/share/prims/jvmtiEnvBase.cpp

@@ -1475,7 +1475,7 @@ JvmtiEnvBase::get_object_monitor_usage(JavaThread* calling_thread, jobject objec
   owning_thread = ObjectSynchronizer::get_lock_owner(tlh.list(), hobj);
   if (owning_thread != nullptr) {
     oop thread_oop = get_vthread_or_thread_oop(owning_thread);
-    bool is_virtual = java_lang_VirtualThread::is_instance(thread_oop);
+    bool is_virtual = thread_oop->is_a(vmClasses::BaseVirtualThread_klass());
     if (is_virtual) {
       thread_oop = nullptr;
     }
@@ -1522,7 +1522,7 @@ JvmtiEnvBase::get_object_monitor_usage(JavaThread* calling_thread, jobject objec
          waiter = mon->next_waiter(waiter)) {
       JavaThread *w = mon->thread_of_waiter(waiter);
       oop thread_oop = get_vthread_or_thread_oop(w);
-      if (java_lang_VirtualThread::is_instance(thread_oop)) {
+      if (thread_oop->is_a(vmClasses::BaseVirtualThread_klass())) {
         skipped++;
       }
       nWait++;
@@ -1572,9 +1572,9 @@ JvmtiEnvBase::get_object_monitor_usage(JavaThread* calling_thread, jobject objec
       for (int i = 0; i < nWait; i++) {
         JavaThread *w = mon->thread_of_waiter(waiter);
         oop thread_oop = get_vthread_or_thread_oop(w);
-        bool is_virtual = java_lang_VirtualThread::is_instance(thread_oop);
+        bool is_virtual = thread_oop->is_a(vmClasses::BaseVirtualThread_klass());
         assert(w != nullptr, "sanity check");
-        if (java_lang_VirtualThread::is_instance(thread_oop)) {
+        if (is_virtual) {
           skipped++;
         } else {
           // If the thread was found on the ObjectWaiter list, then

src/hotspot/share/runtime/threads.cpp

@@ -1196,7 +1196,7 @@ GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list,
     if (!p->can_call_java()) continue;
 
     oop thread_oop = JvmtiEnvBase::get_vthread_or_thread_oop(p);
-    if (java_lang_VirtualThread::is_instance(thread_oop)) {
+    if (thread_oop->is_a(vmClasses::BaseVirtualThread_klass())) {
       continue;
     }
     // The first stage of async deflation does not affect any field