private static void checkGarbageCollectionNotificationInfoContent( GarbageCollectionNotificationInfo notif) throws Exception { System.out.println("GC notification for " + notif.getGcName()); System.out.print("Action: " + notif.getGcAction()); System.out.println(" Cause: " + notif.getGcCause()); GcInfo info = notif.getGcInfo(); System.out.print("GC Info #" + info.getId()); System.out.print(" start:" + info.getStartTime()); System.out.print(" end:" + info.getEndTime()); System.out.println(" (" + info.getDuration() + "ms)"); Map<String, MemoryUsage> usage = info.getMemoryUsageBeforeGc(); List<String> pnames = new ArrayList<String>(); for (Map.Entry entry : usage.entrySet()) { String poolname = (String) entry.getKey(); pnames.add(poolname); MemoryUsage busage = (MemoryUsage) entry.getValue(); MemoryUsage ausage = (MemoryUsage) info.getMemoryUsageAfterGc().get(poolname); if (ausage == null) { throw new RuntimeException("After Gc Memory does not exist" + " for " + poolname); } System.out.println("Usage for pool " + poolname); System.out.println(" Before GC: " + busage); System.out.println(" After GC: " + ausage); } // check if memory usage for all memory pools are returned List<MemoryPoolMXBean> pools = ManagementFactory.getMemoryPoolMXBeans(); for (MemoryPoolMXBean p : pools) { if (!pnames.contains(p.getName())) { throw new RuntimeException( "GcInfo does not contain " + "memory usage for pool " + p.getName()); } } }
public static void main(String[] args) throws Exception { MBeanServer mbs = ManagementFactory.getPlatformMBeanServer(); final Boolean isNotificationSupported = AccessController.doPrivileged( new PrivilegedAction<Boolean>() { public Boolean run() { try { Class cl = Class.forName("sun.management.VMManagementImpl"); Field f = cl.getDeclaredField("gcNotificationSupport"); f.setAccessible(true); return f.getBoolean(null); } catch (ClassNotFoundException e) { return false; } catch (NoSuchFieldException e) { return false; } catch (IllegalAccessException e) { return false; } } }); if (!isNotificationSupported) { System.out.println("GC Notification not supported by the JVM, test skipped"); return; } final ObjectName gcMXBeanPattern = new ObjectName("java.lang:type=GarbageCollector,*"); Set<ObjectName> names = mbs.queryNames(gcMXBeanPattern, null); if (names.isEmpty()) throw new Exception("Test incorrect: no GC MXBeans"); number = names.size(); for (ObjectName n : names) { if (mbs.isInstanceOf(n, "javax.management.NotificationEmitter")) { listenerInvoked.put(n.getCanonicalName(), null); GcListener listener = new GcListener(); mbs.addNotificationListener(n, listener, null, null); } } // Invocation of System.gc() to trigger major GC System.gc(); // Allocation of many short living and small objects to trigger minor GC Object data[] = new Object[32]; for (int i = 0; i < 100000000; i++) { data[i % 32] = new int[8]; } int wakeup = 0; synchronized (synchronizer) { while (count != number) { synchronizer.wait(10000); wakeup++; if (wakeup > 10) break; } } for (GarbageCollectionNotificationInfo notif : listenerInvoked.values()) { checkGarbageCollectionNotificationInfoContent(notif); } System.out.println("Test passed"); }