8328083: degrade virtual thread support for GetObjectMonitorUsage

src/hotspot/share/prims/jvmti.xml

@@ -8256,14 +8256,15 @@ class C2 extends C1 implements I2 {
         <field id="entry_count">
           <jint/>
           <description>
-            The number of times the owning platform thread has entered the monitor
+            The number of times the platform thread owning this monitor has entered it, 
+            or <code>0</code> if owned by a virtual thread or not owned
           </description>
         </field>
         <field id="waiter_count">
           <jint/>
           <description>
-            The number of platform threads waiting to own this monitor,
-            or <code>0</code> if the monitor is owned by a virtual thread or not owned
+            The number of platform threads waiting to own this monitor, or <code>0</code>
+            if only virtual threads are waiting or no threads are waiting
           </description>
         </field>
         <field id="waiters">
@@ -8275,8 +8276,8 @@ class C2 extends C1 implements I2 {
         <field id="notify_waiter_count">
           <jint/>
           <description>
-            The number of platform threads waiting to be notified by this monitor,
-            or <code>0</code> if the monitor is owned by a virtual thread or not owned
+            The number of platform threads waiting to own this monitor, or <code>0</code>
+            if only virtual threads are waiting or no threads are waiting
           </description>
         </field>
         <field id="notify_waiters">

src/java.se/share/data/jdwp/jdwp.spec

@@ -1617,8 +1617,8 @@ JDWP "Java(tm) Debug Wire Protocol"
             (object object "The object ID")
         )
         (Reply
-            (threadObject owner "The platform thread owning this monitor, or <code>nullptr</code> "
-                                "if owned` by a virtual thread or not owned.")
+            (threadObject owner "The platform thread owning this monitor, or null "
+                                "if owned by a virtual thread or not owned.")
             (int entryCount "The number of times the owning platform thread has entered the monitor.")
             (Repeat waiters "The total number of platform threads that are waiting to enter or re-enter "
                             "the monitor, or waiting to be notified by the monitor."

test/hotspot/jtreg/serviceability/jvmti/ObjectMonitorUsage/ObjectMonitorUsage.java

@@ -166,7 +166,7 @@ static void test1(boolean isVirtual) {
         Thread[] eThreads = null;
 
         synchronized (lockCheck) {
-            // Virtual threads are not supported by the GetObjectMonitorUsage.
+            // Virtual threads are not supported by GetObjectMonitorUsage.
             // Correct the expected values for the virtual thread case.
             int expEnteringCount = isVirtual ? 0 : NUMBER_OF_ENTERING_THREADS;
 
@@ -251,7 +251,7 @@ static void test3(boolean isVirtual) throws Error {
         Thread[] eThreads = null;
 
         synchronized (lockCheck) {
-            // Virtual threads are not supported by the GetObjectMonitorUsage.
+            // Virtual threads are not supported by GetObjectMonitorUsage.
             // Correct the expected values for the virtual thread case.
             int expEnteringCount = isVirtual ? 0 : NUMBER_OF_ENTERING_THREADS;
             int expWaitingCount  = isVirtual ? 0 : NUMBER_OF_WAITING_THREADS;

test/hotspot/jtreg/vmTestbase/nsk/jdi/ObjectReference/waitingThreads/waitingthreads002.java

@@ -113,7 +113,6 @@ private static void execTest() {
 
             // Wait up to waitTime until all MyThreads will be blocked on entering in monitor
             int waitingCount = 0;
-            int expWaitingCount = 0;
             long oldTime = System.currentTimeMillis();
             while ((System.currentTimeMillis() - oldTime) <= waitTime && waitingCount < waitingthreads002a.threadCount) {
                 Iterator threads = debuggee.VM().allThreads().iterator();
@@ -125,7 +124,6 @@ private static void execTest() {
                         waitingCount++;
                         // Virtual threads are not present in result returned by objRef.waitingThreads().
                         if (!thread.isVirtual()) {
-                            expWaitingCount++;
                         }
                     }
                 }
@@ -164,6 +162,8 @@ private static void execTest() {
                     objRef = (ObjectReference) debuggeeClass.getValue(debuggeeClass.fieldByName(fieldName));
                     try {
                         List waitingThreads = objRef.waitingThreads();
+                        final boolean vthreadMode = "Virtual".equals(System.getProperty("test.thread.factory"));
+                        final int expWaitingCount = vthreadMode ? 0 : waitingthreads002a.threadCount;
                         if (waitingThreads.size() != expWaitingCount) {
                             exitStatus = Consts.TEST_FAILED;
                             complain("waitingThreads method returned list with unexpected size for " + fieldName +

test/hotspot/jtreg/vmTestbase/nsk/jvmti/GetObjectMonitorUsage/objmonusage001.java

@@ -61,8 +61,9 @@ public static int run(String argv[], PrintStream out) {
             syncObject[i] = new Object();
             runn[i] = new objmonusage001a(mainThread, i, syncObject[i]);
         }
-        // Virtual threads are not supported by the GetObjectMonitorUsage. Correct
-        // the expected values if the test is executed with MainWrapper=virtual.
+        // Virtual threads are not supported by GetObjectMonitorUsage.
+        // Correct the expected values if the test is executed with
+        // JTREG_TEST_THREAD_FACTORY=Virtual.
         Thread expOwner = mainThread.isVirtual() ? null : mainThread;
         int expEntryCount = mainThread.isVirtual() ? 0 : 1;
 
@@ -154,8 +155,9 @@ public objmonusage001a(Thread mt, int i, Object s) {
     }
 
     public void run() {
-        // Virtual threads are not supported by the GetObjectMonitorUsage. Correct
-        // the expected values if the test is executed with MainWrapper=virtual.
+        // Virtual threads are not supported by GetObjectMonitorUsage.
+        // Correct the expected values if the test is executed with
+        // JTREG_TEST_THREAD_FACTORY=Virtual.
         Thread expOwner = this.isVirtual() ? null : this;
         Thread expNotifyWaiter = mainThread.isVirtual() ? null : mainThread;
         int expEntryCount = this.isVirtual() ? 0 : 1;

test/hotspot/jtreg/vmTestbase/nsk/jvmti/GetObjectMonitorUsage/objmonusage004.java

@@ -60,8 +60,9 @@ public static int run(String args[], PrintStream out) {
         Thread currThread = Thread.currentThread();
         ContendThread thr[] = new ContendThread[NUMBER_OF_THREADS];
         synchronized (lockCheck) {
-            // Virtual threads are not supported by the GetObjectMonitorUsage. Correct
-            // the expected values if the test is executed with MainWrapper=virtual.
+            // Virtual threads are not supported by GetObjectMonitorUsage.
+            // Correct the expected values if the test is executed with
+            // JTREG_TEST_THREAD_FACTORY=Virtual.
             Thread expOwner = currThread.isVirtual() ? null : currThread;
             int expEntryCount = currThread.isVirtual() ? 0 : 2;