Tomcat: The Definitive Guide, 2nd Edition

Chapter 4. Tomcat Performance Tuning

Once you have Tomcat up and running, you will likely want to do some performance tuning so that it serves requests more efficiently on your computer. In this chapter, we give you some ideas on performance tuning the underlying Java runtime and the Tomcat server itself.

The art of tuning a server is a complex one. It consists of measuring, understanding, changing, and measuring again. The following are the basic steps in tuning:

1. Decide what needs to be measured.

2. Decide how to measure.

3. Measure.

4. Understand the implications of what you learned.

5. Modify the configuration in ways that are expected to improve the measurements.

6. Measure and compare with previous measurements.

7. Go back to step 4.

Note that, as shown, there is no "exit from loop" clause—perhaps a representative of real life. In practice, you will need to set a threshold below which minor changes are insignificant enough that you can get on with the rest of your life. You can stop adjusting and measuring when you believe you're close enough to the response times that satisfy your requirements.

To decide what to tune for better performance, you should do something like the following.

Set up your Tomcat on a test computer as it will be in your production environment. Try to use the same hardware, the same OS, the same database, etc. The more similar it is to your production environment, the closer you'll be to finding the bottlenecks that you'll have in your production setup.

On a separate machine, install ...