7196801: NPG: Fix java/lang/management/MemoryMXBean/LowMemoryTest2

Reviewed-by: coleenp, sla
Contributed-by: stefan.karlsson@oracle.com, coleen.phillimore@oracle.com

test/java/lang/management/MemoryMXBean/LowMemoryTest2.java

@@ -26,7 +26,7 @@
  *
  * The test set a listener to be notified when any of the non-heap pools
  * exceed 80%. It then starts a thread that continuously loads classes.
- * In the HotSpot implementation this causes perm space to be consumed.
+ * In the HotSpot implementation this causes metaspace to be consumed.
  * Test completes when we the notification is received or an OutOfMemory
  * is generated.
  */
@@ -100,7 +100,14 @@ public class LowMemoryTest2 {
 
             // TestNNNNNN
 
-            String name = "Test" + Integer.toString(count++);
+            int load_count = count++;
+            if (load_count > 999999) {
+                // The test will create a corrupt class file if the count
+                // exceeds 999999. Fix the test if this exception is thrown.
+                throw new RuntimeException("Load count exceeded");
+            }
+
+            String name = "Test" + Integer.toString(load_count);
 
             byte value[];
             try {
@@ -133,8 +140,9 @@ public class LowMemoryTest2 {
          * Note: Once the usage threshold has been exceeded the low memory
          * detector thread will attempt to deliver its notification - this can
          * potentially create a race condition with this thread contining to
-         * fill up perm space. To avoid the low memory detector getting an OutOfMemory
-         * we throttle this thread once the threshold has been exceeded.
+         * fill up metaspace. To avoid the low memory detector getting an
+         * OutOfMemory we throttle this thread once the threshold has been
+         * exceeded.
          */
         public void run() {
             List pools = ManagementFactory.getMemoryPoolMXBeans();
@@ -180,7 +188,7 @@ public class LowMemoryTest2 {
 
         // Set threshold of 80% of all NON_HEAP memory pools
         // In the Hotspot implementation this means we should get a notification
-        // if the CodeCache or perm generation fills up.
+        // if the CodeCache or metaspace fills up.
 
         while (iter.hasNext()) {
             MemoryPoolMXBean p = (MemoryPoolMXBean) iter.next();
@@ -188,7 +196,12 @@ public class LowMemoryTest2 {
 
                 // set threshold
                 MemoryUsage mu = p.getUsage();
-                long threshold = (mu.getMax() * 80) / 100;
+                long max = mu.getMax();
+                if (max < 0) {
+                    throw new RuntimeException("There is no maximum set for "
+                            + p.getName() + " memory pool so the test is invalid");
+                }
+                long threshold = (max * 80) / 100;
 
                 p.setUsageThreshold(threshold);
 

test/java/lang/management/MemoryMXBean/LowMemoryTest2.sh

@@ -51,14 +51,17 @@ go() {
 
 # Run test with each GC configuration
 # 
-# Notes: To ensure that perm gen fills up we disable class unloading.
-# Also we set the max perm space to 8MB - otherwise the test takes too
+# Notes: To ensure that metaspace fills up we disable class unloading.
+# Also we set the max metaspace to 8MB - otherwise the test takes too
 # long to run. 
 
-go -noclassgc -XX:PermSize=8m -XX:MaxPermSize=8m -XX:+UseSerialGC LowMemoryTest2
-go -noclassgc -XX:PermSize=8m -XX:MaxPermSize=8m -XX:+UseParallelGC LowMemoryTest2
-go -noclassgc -XX:PermSize=8m -XX:MaxPermSize=8m -XX:+UseParNewGC -XX:+UseConcMarkSweepGC \
-    LowMemoryTest2
+go -noclassgc -XX:MaxMetaspaceSize=16m -XX:+UseSerialGC LowMemoryTest2
+go -noclassgc -XX:MaxMetaspaceSize=16m -XX:+UseParallelGC LowMemoryTest2
+go -noclassgc -XX:MaxMetaspaceSize=16m -XX:+UseParNewGC -XX:+UseConcMarkSweepGC LowMemoryTest2
+
+# Test class metaspace - might hit MaxMetaspaceSize instead if
+# UseCompressedClassPointers is off or if 32 bit.
+go -noclassgc -XX:MaxMetaspaceSize=16m -XX:CompressedClassSpaceSize=4m LowMemoryTest2
 
 echo ''
 if [ $failures -gt 0 ];