alvinalexander.com | career | drupal | java | mac | mysql | perl | scala | uml | unix  

Java example source code file (GarbageCollectionNotificationContentTest.java)

This example Java source code file (GarbageCollectionNotificationContentTest.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

action, boolean, class, exception, garbagecollectionnotificationinfo, gcinfo, gclistener, hashmap, management, memoryusage, object, objectname, reflection, runtimeexception, security, string, util

The GarbageCollectionNotificationContentTest.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 GarbageCollectionNotification contents are reasonable
 * @author  Frederic Parain
 * @run     main/othervm GarbageCollectionNotificationContentTest
 */

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 GarbageCollectionNotificationContentTest {
    private static HashMap<String,GarbageCollectionNotificationInfo> listenerInvoked
        = new HashMap<String,GarbageCollectionNotificationInfo>();
    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) == null) {
                            listenerInvoked.put(((ObjectName)notif.getSource()).getCanonicalName(),gcNotif);
                            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(),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");
    }

    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();
        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());
            }
        }
    }
}

Other Java examples (source code examples)

Here is a short list of links related to this Java GarbageCollectionNotificationContentTest.java source code file:

... this post is sponsored by my books ...

#1 New Release!

FP Best Seller

 

new blog posts

 

Copyright 1998-2024 Alvin Alexander, alvinalexander.com
All Rights Reserved.

A percentage of advertising revenue from
pages under the /java/jwarehouse URI on this website is
paid back to open source projects.