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");
}