Calculate JVM CPU Usage Using MXBeans

JVMCPUUsage.java

/* JVMCPUUsage
 *
 * Calculate JVM CPU usage on older than JDK version 7 using MXBeans.
 *
 * First initiate MBeanServerConnection using `openMBeanServerConnection` method. Then
 * create proxy connections to MXBeans using `getMXBeanProxyConnections` and after that
 * poll `getJvmCpuUsage` method periodically.
 *
 * JVMCPUUsage is a free Java class:
 * you can redistribute it and/or modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation, either version 3 of the License, or(at your option)
 * any later version. 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 for more details.
 * See COPYING for a copy of the GNU General Public License. If not, see <http://www.gnu.org/licenses/>.
 *
 * Copyright (C) 2017  Lahiru Pathirage <lpsandaruwan@gmail.com> on 3/27/17.
 */

import javax.management.MBeanServerConnection;
import javax.management.remote.JMXConnector;
import javax.management.remote.JMXConnectorFactory;
import javax.management.remote.JMXServiceURL;
import java.io.IOException;
import java.lang.management.ManagementFactory;
import java.lang.management.OperatingSystemMXBean;
import java.lang.management.RuntimeMXBean;


public class JVMCPUUsage {
    // hardcoded connection parameters
    private final String HOSTNAME = "localhost";
    private final int PORT = 9999;

    private MBeanServerConnection mBeanServerConnection;
    private com.sun.management.OperatingSystemMXBean peOperatingSystemMXBean;
    private OperatingSystemMXBean operatingSystemMXBean;
    private RuntimeMXBean runtimeMXBean;

    // keeping previous timestamps
    private long previousJvmProcessCpuTime = 0;
    private long previousJvmUptime = 0;

    // initiate and prepare MBeanServerConnection
    public void openMBeanServerConnection() throws IOException {
        // initiate address of the JMX API connector server
        String serviceURL = "service:jmx:rmi:///jndi/rmi://" + HOSTNAME + ":" + PORT + "/jmxrmi";
        JMXServiceURL jmxServiceURL = new JMXServiceURL(serviceURL);

        // initiate client side JMX API connector
        // here we set environment attributes to null, because it is not a necessity to what we're going to do
        JMXConnector jmxConnector = JMXConnectorFactory.connect(jmxServiceURL, null);

        // initiate management bean server connection
        mBeanServerConnection = jmxConnector.getMBeanServerConnection();
    }

    // initiate and prepare MXBean interfaces proxy connections
    public void getMXBeanProxyConnections() throws IOException {
        peOperatingSystemMXBean = ManagementFactory.newPlatformMXBeanProxy(
                mBeanServerConnection,
                ManagementFactory.OPERATING_SYSTEM_MXBEAN_NAME,
                com.sun.management.OperatingSystemMXBean.class
        );
        operatingSystemMXBean = ManagementFactory.newPlatformMXBeanProxy(
                mBeanServerConnection,
                ManagementFactory.OPERATING_SYSTEM_MXBEAN_NAME,
                OperatingSystemMXBean.class
        );
        runtimeMXBean = ManagementFactory.newPlatformMXBeanProxy(
                mBeanServerConnection,
                ManagementFactory.RUNTIME_MXBEAN_NAME,
                RuntimeMXBean.class
        );
    }

    // Get JVM CPU usage
    public float getJvmCpuUsage() {
        // elapsed process time is in nanoseconds
        long elapsedProcessCpuTime = peOperatingSystemMXBean.getProcessCpuTime() - previousJvmProcessCpuTime;
        // elapsed uptime is in milliseconds
        long elapsedJvmUptime = runtimeMXBean.getUptime() - previousJvmUptime;

        // total jvm uptime on all the available processors
        long totalElapsedJvmUptime = elapsedJvmUptime * operatingSystemMXBean.getAvailableProcessors();

        // calculate cpu usage as a percentage value
        // to convert nanoseconds to milliseconds divide it by 1000000 and to get a percentage multiply it by 100
        float cpuUsage = elapsedProcessCpuTime / (totalElapsedJvmUptime * 10000F);

        // set old timestamp values
        previousJvmProcessCpuTime = peOperatingSystemMXBean.getProcessCpuTime();
        previousJvmUptime = runtimeMXBean.getUptime();

        return cpuUsage;
    }
}