Adjust ThreadListStackTracesTest for checkReentrantLock

Adjust ThreadListStackTracesTest for checkReentrantLock
to be ready when the virtual thread state is WAITING after
the reentrant lock parks the virtual thread. When the
virtual thread is mounted, the virtual thread state, which
is obtained from the carrier thread, can transition
between WAITING and RUNNABLE before the reentrant lock
parks the virtual thread.

Issue: eclipse-openj9/openj9#18089
Signed-off-by: Amarpreet Singh <[email protected]>

test/hotspot/jtreg/serviceability/jvmti/vthread/ThreadListStackTracesTest/ThreadListStackTracesTest.java

@@ -45,6 +45,8 @@ static void sleep(long millis) {
     }
 
     public void ensureReady(Thread vt, Thread.State expState) {
+        // sleep for 1 second to allow the thread to reach the expected state
+        sleep(1000);
         // wait while the thread is not ready or thread state is unexpected
         while (!threadReady || (vt.getState() != expState)) {
             sleep(1);
@@ -86,6 +88,14 @@ public class ThreadListStackTracesTest {
     static void log(String msg) { System.out.println(msg); }
     static void failed(String msg) { throw new RuntimeException(msg); }
 
+    static void sleep(long millis) {
+        try {
+            Thread.sleep(millis);
+        } catch (InterruptedException e) {
+            throw new RuntimeException("Interruption in ThreadListStackTracesTest.sleep: \n\t" + e);
+        }
+    }
+
     public static void main(String[] args) throws InterruptedException {
         checkReentrantLock();
         checkSynchronized();
@@ -97,6 +107,10 @@ private static void checkReentrantLock() throws InterruptedException {
         String name = "ReentrantLockTestTask";
         TestTask task = new ReentrantLockTestTask();
         Thread vt = Thread.ofVirtual().name(name).start(task);
+        // wait until vt is waiting to acquire the lock
+        while (!reentrantLock.hasQueuedThread(vt)) {
+            sleep(1);
+        }
         task.ensureReady(vt, expState);
         checkStates(vt, expState);
     }