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Java example source code file (GetCommittedVirtualMemorySize.java)

This example Java source code file (GetCommittedVirtualMemorySize.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.

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Java - Java tags/keywords

committed, getcommittedvirtualmemorysize, management, max, min_size_for_pass, operatingsystemmxbean, runtimeexception

The GetCommittedVirtualMemorySize.java Java example source code

/*
 * Copyright (c) 2003, 2004, 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     4858522 6191542
 * @summary Basic unit test of OperatingSystemMXBean.getCommittedVirtualMemorySize()
 * @author  Steve Bohne
 */

/*
 * This test is just a sanity check and does not check for the correct
 * value.  The correct value should be checked manually:
 * Solaris:
 *   1. In a shell, enter the command: "ps -efly"
 *   2. Find your process, and look in the "SZ" column.  Reported in Kbytes.
 * Linux:
 *   1. In a shell, enter the command: "ps -efly"
 *   2. Find your process, and look in the "SZ" column.  Reported in Kbytes.
 * Windows NT/XP/2000:
 *   1. Hit Ctrl-Alt-Delete, select Task Manager, go to Processes tab.
 *   2. Find your process and look in the "Mem Usage" column.  Reported in
 *      Kbytes.
 * Windows 98/ME:
 *   Not supported.
 */

import com.sun.management.OperatingSystemMXBean;
import java.lang.management.*;

public class GetCommittedVirtualMemorySize {

    private static OperatingSystemMXBean mbean =
        (com.sun.management.OperatingSystemMXBean)
        ManagementFactory.getOperatingSystemMXBean();

    // Careful with these values.
    private static final long MIN_SIZE_FOR_PASS = 1;
    // Max size for pass dynamically determined below
    private static long       max_size_for_pass = Long.MAX_VALUE;

    private static boolean trace = false;

    public static void main(String args[]) throws Exception {
        if (args.length > 0 && args[0].equals("trace")) {
            trace = true;
        }

        // 4934082: On Linux, VM size *can* be larger than total swap
        // size.  Linux might not reserve swap memory immediately when
        // a page is mmaped.  This means that the reported committed
        // memory size can grow beyond the swap limit.
        long max_size = mbean.getTotalSwapSpaceSize() +
                        mbean.getTotalPhysicalMemorySize();

        if (max_size > 0) {
            max_size_for_pass = max_size;
        }
        long size = mbean.getCommittedVirtualMemorySize();
        if (size == -1) {
            System.out.println("getCommittedVirtualMemorySize() is not supported");
            return;
        }

        if (trace) {
            System.out.println("Committed virtual memory size in bytes: " +
                               size);
        }

        if (size < MIN_SIZE_FOR_PASS || size > max_size_for_pass) {
            throw new RuntimeException("Committed virtual memory size " +
                                       "illegal value: " + size + " bytes " +
                                       "(MIN = " + MIN_SIZE_FOR_PASS + "; " +
                                       "MAX = " + max_size_for_pass + ")");
        }

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

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