How to find memory usage of web applications in apache tomcat

Question

I'm working on a project where I need to find the memory usage of web applications deployed in Apache tomcat. In an intranet architecture i'd like to develop a tool to find the users accessing the deployed web application and its memory being used. Could someone help me start off with this project. I have configured Apache tomcat and deployed few web applications now. Performance monitoring is the objective of my project. Thank You.

Answer 1

You can access the memory usage for the Tomcat JVM using JMX pretty easy. See this SO for more info. Please note that you will get memory usage for tomcat + all deployed web apps. You cannot get memory usage for a single webapp, since Tomcat share a single java process for both container and apps. If you want better control over memory usage per app, I suggest you either use a more sophisticated application server or use a tomcat instance per webapp.

To monitor connected users, I guess you have to do something on the application layer. Tomcat is not really aware of the concept of "user", since that is typically something you implement in the code (like Spring Security).

Answer 2

Did you read this? You can't, please read http://wiki.apache.org/tomcat/FAQ/Memory (archive.org copy) too:

You can't find out how much memory a web application is using. The JVM doesn't give us these detail or information.