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 *

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 * modification, are permitted provided that the following conditions

 * are met:

 *

 *   - Redistributions of source code must retain the above copyright

 *     notice, this list of conditions and the following disclaimer.

 *

 *   - Redistributions in binary form must reproduce the above copyright

 *     notice, this list of conditions and the following disclaimer in the

 *     documentation and/or other materials provided with the distribution.

 *

 *   - Neither the name of Oracle nor the names of its

 *     contributors may be used to endorse or promote products derived

 *     from this software without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS

 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,

 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR

 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,

 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,

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 */

/*

 * This source code is provided to illustrate the usage of a given feature

 * or technique and has been deliberately simplified. Additional steps

 * required for a production-quality application, such as security checks,

 * input validation and proper error handling, might not be present in

 * this sample code.

 */

/*

 */

import static java.lang.management.ManagementFactory.*;

import java.lang.management.*;

import javax.management.*;

import java.io.*;

import java.util.*;

/**

 * Example of using the java.lang.management API to monitor

 * the memory usage and garbage collection statistics.

 *

 * @author  Mandy Chung

 */

public class PrintGCStat {

    private RuntimeMXBean rmbean;

    private MemoryMXBean mmbean;

    private List<MemoryPoolMXBean> pools;

    private List<GarbageCollectorMXBean> gcmbeans;

    /**

     * Constructs a PrintGCStat object to monitor a remote JVM.

     */

    public PrintGCStat(MBeanServerConnection server) throws IOException {

        // Create the platform mxbean proxies

        this.rmbean = newPlatformMXBeanProxy(server,

                                             RUNTIME_MXBEAN_NAME,

                                             RuntimeMXBean.class);

        this.mmbean = newPlatformMXBeanProxy(server,

                                             MEMORY_MXBEAN_NAME,

                                             MemoryMXBean.class);

        ObjectName poolName = null;

        ObjectName gcName = null;

        try {

            poolName = new ObjectName(MEMORY_POOL_MXBEAN_DOMAIN_TYPE+",*");

            gcName = new ObjectName(GARBAGE_COLLECTOR_MXBEAN_DOMAIN_TYPE+",*");

        } catch (MalformedObjectNameException e) {

            // should not reach here

            assert(false);

        }

        Set<ObjectName> mbeans = server.queryNames(poolName, null);

        if (mbeans != null) {

            pools = new ArrayList<MemoryPoolMXBean>();

            for (ObjectName objName : mbeans) {

                MemoryPoolMXBean p =

                    newPlatformMXBeanProxy(server,

                                           objName.getCanonicalName(),

                                           MemoryPoolMXBean.class);

                pools.add(p);

            }

        }

        mbeans = server.queryNames(gcName, null);

        if (mbeans != null) {

            gcmbeans = new ArrayList<GarbageCollectorMXBean>();

            for (ObjectName objName : mbeans) {

                GarbageCollectorMXBean gc =

                    newPlatformMXBeanProxy(server,

                                           objName.getCanonicalName(),

                                           GarbageCollectorMXBean.class);

                gcmbeans.add(gc);

            }

        }

    }

    /**

     * Constructs a PrintGCStat object to monitor the local JVM.

     */

    public PrintGCStat() {

        // Obtain the platform mxbean instances for the running JVM.

        this.rmbean = getRuntimeMXBean();

        this.mmbean = getMemoryMXBean();

        this.pools = getMemoryPoolMXBeans();

        this.gcmbeans = getGarbageCollectorMXBeans();

    }

    /**

     * Prints the verbose GC log to System.out to list the memory usage

     * of all memory pools as well as the GC statistics.

     */

    public void printVerboseGc() {

        System.out.println("Uptime: " + formatMillis(rmbean.getUptime()));

        System.out.println("Heap usage: " + mmbean.getHeapMemoryUsage());

        System.out.println("Non-Heap memory usage: " + mmbean.getNonHeapMemoryUsage());

        for (GarbageCollectorMXBean gc : gcmbeans) {

            System.out.print(" [" + gc.getName() + ": ");

            System.out.print("Count=" + gc.getCollectionCount());

            System.out.print(" GCTime=" + formatMillis(gc.getCollectionTime()));

            System.out.print("]");

        }

        System.out.println();

        for (MemoryPoolMXBean p : pools) {

            System.out.print("  [" + p.getName() + ":");

            MemoryUsage u = p.getUsage();

            System.out.print(" Used=" + formatBytes(u.getUsed()));

            System.out.print(" Committed=" + formatBytes(u.getCommitted()));

            System.out.println("]");

        }

    }

    private String formatMillis(long ms) {

        return String.format("%.4fsec", ms / (double) 1000);

    }

    private String formatBytes(long bytes) {

        long kb = bytes;

        if (bytes > 0) {

            kb = bytes / 1024;

        }

        return kb + "K";

    }

}