test/jdk/java/lang/management/MemoryMXBean/LowMemoryTest.java

*** 81,93 ****
          final String g1Flag = "-XX:G1HeapRegionSize=1m";
  
          // Runs the test collecting subprocess I/O while it's running.
          traceTest(classMain + ", -XX:+UseSerialGC", nmFlag, lpFlag, "-XX:+UseSerialGC");
          traceTest(classMain + ", -XX:+UseParallelGC", nmFlag, lpFlag, "-XX:+UseParallelGC");
!         traceTest(classMain + ", -XX:+UseG1GC", nmFlag, lpFlag, "-XX:+UseG1GC", g1Flag);
          if (!Compiler.isGraalEnabled()) { // Graal does not support CMS
!             traceTest(classMain + ", -XX:+UseConcMarkSweepGC", nmFlag, lpFlag, "-XX:+UseConcMarkSweepGC");
          }
      }
  
      /*
       * Creating command-line for running subprocess JVM:
--- 81,97 ----
          final String g1Flag = "-XX:G1HeapRegionSize=1m";
  
          // Runs the test collecting subprocess I/O while it's running.
          traceTest(classMain + ", -XX:+UseSerialGC", nmFlag, lpFlag, "-XX:+UseSerialGC");
          traceTest(classMain + ", -XX:+UseParallelGC", nmFlag, lpFlag, "-XX:+UseParallelGC");
!         traceTest(classMain + ", -XX:+UseG1GC -XX:-G1UseLegacyMonitoring", nmFlag, lpFlag,
!                   "-XX:+UseG1GC", "-XX:-G1UseLegacyMonitoring", g1Flag);
!         traceTest(classMain + ", -XX:+UseG1GC -XX:+G1UseLegacyMonitoring", nmFlag, lpFlag,
!                   "-XX:+UseG1GC", "-XX:+G1UseLegacyMonitoring", g1Flag);
          if (!Compiler.isGraalEnabled()) { // Graal does not support CMS
!              traceTest(classMain + ", -XX:+UseConcMarkSweepGC", nmFlag, lpFlag,
!                        "-XX:+UseConcMarkSweepGC");
          }
      }
  
      /*
       * Creating command-line for running subprocess JVM:
*** 232,250 ****
--- 236,268 ----
              ListIterator iter = pools.listIterator();
              while (iter.hasNext()) {
                  MemoryPoolMXBean p = (MemoryPoolMXBean) iter.next();
                  if (p.getType() == MemoryType.HEAP &&
                      p.isUsageThresholdSupported()) {
+                     if (!p.getName().equals("G1 Old Space")) {
+                         // In G1, humongous objects are tracked in the old space only in
+                         // legacy monitoring mode. In default mode, G1 tracks humongous
+                         // objects in the humongous space, which latter also supports a
+                         // usage threshold. Since we're allocating humongous objects in
+                         // this test, in default mode the old space doesn't change. For
+                         // this test, we use the old space in legacy mode (it's called
+                         // "G1 Old Gen" and the humongous space in default mode. If we
+                         // used "G1 Old Space" in default mode, notification would never
+                         // happen.
                          mpool = p;
                          if (trace) {
                              System.out.println("Selected memory pool for low memory " +
                                                 "detection.");
                              MemoryUtil.printMemoryPool(mpool);
                          }
                          break;
                      }
                  }
+             }
+             if (mpool == null) {
+                 throw new RuntimeException("TEST FAILED: No heap pool found");
+             }
  
              TestListener listener = new TestListener();
              SensorListener l2 = new SensorListener();
              NotificationEmitter emitter = (NotificationEmitter) mm;
              emitter.addNotificationListener(listener, null, null);