8309329: com/sun/jdi/DeferredStepTest.java fails with virtual threads due to not waiting for threads to exit

Reviewed-by: sspitsyn, lmesnik, amenkov

Author: plummercj

test/jdk/ProblemList-Virtual.txt

@@ -27,7 +27,6 @@ com/sun/jdi/EATests.java#id0                                    8264699 generic-
 ## Tests failing when main() is executed in additional vthread or in vthread instead of thread
 #
 
-com/sun/jdi/DeferredStepTest.java 8285422 generic-all
 com/sun/jdi/ExceptionEvents.java 8285422 generic-all
 com/sun/jdi/JdbMethodExitTest.java 8285422 generic-all
 com/sun/jdi/JdbStepTest.java 8285422 generic-all

test/jdk/com/sun/jdi/DeferredStepTest.java

@@ -74,8 +74,17 @@ public static void  main(String argv[]) {
 
         jj1 obj1 = new jj1();
         jj2 obj2 = new jj2();
-        TestScaffold.newThread(obj1, "jj1").start();
-        TestScaffold.newThread(obj2, "jj2").start();
+        Thread thread1 = TestScaffold.newThread(obj1, "jj1");
+        Thread thread2 = TestScaffold.newThread(obj2, "jj2");
+        thread1.start();
+        thread2.start();
+        // Threads might be deamon threads, so wait here for them to complete.
+        try {
+            thread1.join();
+            thread2.join();
+        } catch (InterruptedException ie) {
+            throw new RuntimeException(ie);
+        }
     }
 }