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Java example source code file (GarbageCollectionNotificationTest.java)
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The GarbageCollectionNotificationTest.java Java example source code
/*
* Copyright (c) 2011, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
/*
* @test
* @bug 7036199
* @summary Check that GarbageCollection notification are thrown by every GarbageCollectorMXBean
* @author Frederic Parain
* @run main/othervm GarbageCollectionNotificationTest
*/
import java.util.*;
import java.lang.management.*;
import java.lang.reflect.*;
import javax.management.*;
import javax.management.openmbean.*;
import com.sun.management.GarbageCollectionNotificationInfo;
import com.sun.management.GcInfo;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.lang.reflect.Field;
public class GarbageCollectionNotificationTest {
private static HashMap<String,Boolean> listenerInvoked = new HashMap();
static volatile long count = 0;
static volatile long number = 0;
static Object synchronizer = new Object();
static class GcListener implements NotificationListener {
public void handleNotification(Notification notif, Object handback) {
String type = notif.getType();
if (type.equals(GarbageCollectionNotificationInfo.GARBAGE_COLLECTION_NOTIFICATION)) {
GarbageCollectionNotificationInfo gcNotif =
GarbageCollectionNotificationInfo.from((CompositeData) notif.getUserData());
String source = ((ObjectName)notif.getSource()).getCanonicalName();
synchronized(synchronizer) {
if(!listenerInvoked.get(source)) {
listenerInvoked.put(((ObjectName)notif.getSource()).getCanonicalName(),true);
count++;
if(count >= number) {
synchronizer.notify();
}
}
}
}
}
}
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(),false);
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 (String source : listenerInvoked.keySet()) {
if(!listenerInvoked.get(source))
throw new Exception("Test incorrect: notifications have not been sent for "
+ source);
}
System.out.println("Test passed");
}
}
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