Java example source code file (ThreadAllocatedMemoryArray.java)

This example Java source code file (ThreadAllocatedMemoryArray.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

caught, failed, illegalargumentexception, interruptedexception, invalid, management, mythread, nullpointerexception, num_threads, object, runtimeexception, string, test, threadallocatedbytes, threadallocatedmemory

The ThreadAllocatedMemoryArray.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     6173675
 * @summary Basic test of ThreadMXBean.getThreadAllocatedBytes(long[])
 * @author  Paul Hohensee
 */

import java.lang.management.*;

public class ThreadAllocatedMemoryArray {
    private static com.sun.management.ThreadMXBean mbean =
        (com.sun.management.ThreadMXBean)ManagementFactory.getThreadMXBean();
    private static boolean testFailed = false;
    private static boolean done = false;
    private static boolean done1 = false;
    private static Object obj = new Object();
    private static final int NUM_THREADS = 10;
    private static Thread[] threads = new Thread[NUM_THREADS];

    public static void main(String[] argv)
        throws Exception {

        if (!mbean.isThreadAllocatedMemorySupported()) {
            return;
        }


        // start threads, wait for them to block
        long[] ids = new long[NUM_THREADS];

        for (int i = 0; i < NUM_THREADS; i++) {
            threads[i] = new MyThread("MyThread-" + i);
            threads[i].start();
            ids[i] = threads[i].getId();
        }

        waitUntilThreadBlocked();


        // disable allocated memory measurement
        if (mbean.isThreadAllocatedMemoryEnabled()) {
            mbean.setThreadAllocatedMemoryEnabled(false);
        }

        if (mbean.isThreadAllocatedMemoryEnabled()) {
            throw new RuntimeException(
                "ThreadAllocatedMemory is expected to be disabled");
        }

        long sizes[] = mbean.getThreadAllocatedBytes(ids);

        if (sizes == null) {
          throw new RuntimeException("Null ThreadAllocatedBytes array returned");
        }

        for (int i = 0; i < NUM_THREADS; i++) {
            long s = sizes[i];
            if (s != -1) {
                throw new RuntimeException(
                    "Invalid ThreadAllocatedBytes returned for thread " +
                    threads[i].getName() + " = " +  s + " expected = -1");
            }
        }

        // Enable allocated memory measurement
        if (!mbean.isThreadAllocatedMemoryEnabled()) {
            mbean.setThreadAllocatedMemoryEnabled(true);
        }

        if (!mbean.isThreadAllocatedMemoryEnabled()) {
            throw new RuntimeException(
                "ThreadAllocatedMemory is expected to be enabled");
        }

        sizes = mbean.getThreadAllocatedBytes(ids);

        for (int i = 0; i < NUM_THREADS; i++) {
            long s = sizes[i];
            if (s < 0) {
                throw new RuntimeException(
                    "Invalid allocated bytes returned for thread " +
                    threads[i].getName() + " = " + s);
            }
        }

        // let threads go and do some more allocation
        synchronized (obj) {
            done = true;
            obj.notifyAll();
        }

        // wait for threads to get going again.  we don't care if we
        // catch them in mid-execution or if some of them haven't
        // restarted after we're done sleeping.
        goSleep(400);

        long[] sizes1 = mbean.getThreadAllocatedBytes(ids);

        for (int i = 0; i < NUM_THREADS; i++) {
            long newSize = sizes1[i];
            if (sizes[i] > newSize) {
                throw new RuntimeException("TEST FAILED: " +
                    threads[i].getName() +
                    " previous allocated bytes = " + sizes[i] +
                    " > current allocated bytes = " + newSize);
            }
            System.out.println(threads[i].getName() +
                " Previous allocated bytes = " + sizes[i] +
                " Current allocated bytes = " + newSize);
        }

        try {
            sizes = mbean.getThreadAllocatedBytes(null);
        } catch (NullPointerException e) {
            System.out.println(
                "Caught expected NullPointerException: " + e.getMessage());
        }

        try {
            ids[0] = 0;
            sizes = mbean.getThreadAllocatedBytes(ids);
        } catch (IllegalArgumentException e) {
            System.out.println(
                "Caught expected IllegalArgumentException: " + e.getMessage());
        }


        // let threads exit
        synchronized (obj) {
            done1 = true;
            obj.notifyAll();
        }

        for (int i = 0; i < NUM_THREADS; i++) {
            try {
                threads[i].join();
            } catch (InterruptedException e) {
                System.out.println("Unexpected exception is thrown.");
                e.printStackTrace(System.out);
                testFailed = true;
                break;
            }
        }

        if (testFailed) {
            throw new RuntimeException("TEST FAILED");
        }

        System.out.println("Test passed");
    }


    private static void goSleep(long ms) throws Exception {
        try {
            Thread.sleep(ms);
        } catch (InterruptedException e) {
            System.out.println("Unexpected exception is thrown.");
            throw e;
        }
    }

    private static void waitUntilThreadBlocked()
        throws Exception {
        int count = 0;
        while (count != NUM_THREADS) {
            goSleep(100);
            count = 0;
            for (int i = 0; i < NUM_THREADS; i++) {
                ThreadInfo info = mbean.getThreadInfo(threads[i].getId());
                if (info.getThreadState() == Thread.State.WAITING) {
                    count++;
                }
            }
        }
    }

    public static void doit() {
        String tmp = "";
        long hashCode = 0;
        for (int counter = 0; counter < 1000; counter++) {
            tmp += counter;
            hashCode = tmp.hashCode();
        }
        System.out.println(Thread.currentThread().getName() +
                           " hashcode: " + hashCode);
    }

    static class MyThread extends Thread {
        public MyThread(String name) {
            super(name);
        }

        public void run() {
            ThreadAllocatedMemoryArray.doit();

            synchronized (obj) {
                while (!done) {
                    try {
                        obj.wait();
                    } catch (InterruptedException e) {
                        System.out.println("Unexpected exception is thrown.");
                        e.printStackTrace(System.out);
                        testFailed = true;
                        break;
                    }
                }
            }

            ThreadAllocatedMemoryArray.doit();

            synchronized (obj) {
                while (!done1) {
                    try {
                        obj.wait();
                    } catch (InterruptedException e) {
                        System.out.println("Unexpected exception is thrown.");
                        e.printStackTrace(System.out);
                        testFailed = true;
                        break;
                    }
                }
            }

        }
    }
}