jvmstat code demo

In last post, I showed how you can connect to a locally running jvm's jmx agent using java attach api and get various monitoring statistics from the in built jmx beans. In addition to jmx beans, you can gather similar information from jvm using the sun.jvmstat.monitor pacakge.

import sun.jvmstat.monitor.Monitor;
import sun.jvmstat.monitor.MonitoredHost;
import sun.jvmstat.monitor.MonitoredVm;
import sun.jvmstat.monitor.VmIdentifier;

/**
 * This example demonstrates the usage of sun jvmstat package to connect to a jvm
 * running locally(given the vm id obtained using jps command) and print out the
 * count of live threads.
 * 
 * You have to add $(jdk-home)/lib/tools.jar in your class path to compile/run
 * this code.
 *
 * @author Himanshu Gupta
 */
public class JvmStatDemo {

    public static void main(String[] args) throws Exception {
        String id = args[0];
        VmIdentifier vmId = new VmIdentifier(id);
        MonitoredHost monitoredHost = MonitoredHost.getMonitoredHost(vmId);
        MonitoredVm monitoredVm = monitoredHost.getMonitoredVm(vmId, 5);
        Monitor m = monitoredVm.findByName("java.threads.live");
        System.out.println("Number of live threads = " + m.getValue());
        
        //You can print whole list of monitored stuff
        /* List logged = monitoredVm.findByPattern(".*");
        for(Iterator i = logged.iterator(); i.hasNext(); ) {
            m = i.next();
            System.out.println(m.getName() + " : " + m.getValue());
        } */
    }
}

Jstat uses above mechanism to give locally running jvm monitoring information.