JMX: Monitor and Manage JVM

You can use JMX to monitor and manage JVM. Let me explain with an example.

Test.java

package com.sample.app;

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.TimeUnit;

public class Test {

	private static List<Integer> tempList = new ArrayList<> ();
	
	public static void main(String args[]) throws InterruptedException {
		while(true) {
			tempList = new ArrayList<> ();
			
			for(int i=0; i < 10000000; i++) {
				tempList.add(i);
			}
			
			TimeUnit.SECONDS.sleep(10);
			
		}
	}
}

Run Test.java.

Open command prompt (or) terminal and execute the command jconsole.

Select the process with name ‘com.sample.app.Test’ and click on Connect button.

If you see below kind of window, click on ‘Insecure Connection’ button.

It launches below window.

In the overview section, you can able to see

a.   Heap memory usage of the application

b.   Number of threads

c.   Number of loaded classes

d.   CPU consumption usage details

Go to Memory tab, to see detailed report on Heap Memory usage.

If you want to see complete summary of the memory, cpu and operating system details, click on ‘VM Summary’ tab.

How to request for garbage collection from jconsole?

Go to Memory tab and click on ‘Perform GC’ button.

Before click on ‘Perform GC’ button.

After clicking ‘Perform GC’ button.

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