A few days back, I faced an issue on one of the Java service-hosted servers. The server load, resource consumption, and response time of service were too high.

Everyone was under the impression that the latest deployment of the JAR caused this issue, whereas the service code and performance on the local machine looked fine.

To be sure, we need data for the latest deployment to not cause this issue — that's where the use case of JVisualVM comes.

What Is the JVisualVM?

This is one of the useful, free utilities that come in the JDK bundle. It's basically a JMX client application. This utility shows stats like memory used, heap data, garbage collector, and CPU profiling.

It helps us to improve the application performance after analyzing memory leaks, heap data, and CPU consumption

With features like thread analysis and head dump analysis, it is very handy in solving run-time problems, too.

Adding JMX Properties

To enable JVisualVM to collect stats of application hosted on a remote server, we have to run our application with jmx system properties. They are as follows:

• com.sun.management.jmxremote.port to specify the port number through which the application will be exposed
• com.sun.management.jmxremote.ssl to specify whether secure sockets layer (SSL) encryption will be activated to secure the connection to the application
• com.sun.management.jmxremote.authenticate to specify whether the connection will be password protected

Jar command looks like:

 java -jar -Dcom.sun.management.jmxremote.port=1098 -Dcom.sun.management.jmxremote.authenticate=false -Dcom.sun.management.jmxremote.ssl=false my-service.jar

Running JVisualVM on a Local Machine

I am an Ubuntu user and jvisualvm is available at:

 /usr/lib/jvm/java-8-oracle/bin/jvisualvm 

We can run jvisualVM using the following command in bash terminal as follows:

The application will launch as follows:

Create SOCKS Proxy Connection

The SOCKS proxy can be created either by SOCKS client or ssh utility on Linux.

We usedthe following command to create a secure tunnel between localhost and remote server:

ssh -fN -D 1098 my-username@my-remote-server-IP -pXXXX

-f option forks the process and tunnel create command runs in the background

-N option tells ssh that we don’t send any command once the tunnel setup

completed

-D option used to select the listening port

 -p  Port to connect to on the remote host

You will be asked password to set up the SOCKS proxy.

Add Proxy Setting in JVisualVM

Use following steps from the tools menu:

Tools->Options->Network – Manual Proxy Settings – check it and configure SOCKS Proxy at localhost and port 1098

Add Remote Host in JVisualVM

Use the following steps from the JVisualVM sidebar.

Right click on the remote host -> Add remote host -- Type the IP of the server

Note: I have added display name myserver to hide the serverIP

Add JMX Connection

Use following steps to add the JMX connection

Right click on myserver->Type the jmx port (add 1098)

Note: I have added display name myservice-on-myserver to hide the serverIP.

Collecting Stats

Now, we can analyze the collected stats like CPU usage, system properties, detailed Threads report with access to stack traces, CPU sampling, etc.

Final snapshot will be like as follows:

All the best on your JVisualVM endeavors!