Introduction

This document describes instructions for optimizing Tomcat performance on the System i.

Optimizing Tomcat Performance

Java performance on newer IBM System i operating systems and hardware models has significantly improved in 2008-2009 timeframe. At the time of this writing, optimum performance can be achieved running:

1.  JDK 1.6 or Java 6 IBM Technology for Java (32bit and 64 Bit)                 

1. Available on V6R1                
2. Available as a PTF on V5R4

2.  Tomcat 6        

3.  V6R1 of OS400

For overview information, review the following links:

http://systeminetwork.com/article/32-bit-jvm-i

http://www.ibmsystemsmag.com/ibmi/may08/developer/20547p1.aspx

These options are not always available but having knowledge of upcoming capabilities is useful.

Configuring Tomcat on System I

In many cases, the IBM Technology for Java JVM can provide performance improvements. Follow these steps below to configure Tomcat to run with the 32 bit version.

NOTE: These instructions are only applicable for V5R4 customers and only pertain to JDK1.5 although JDK 1.6 is desirable if it can be obtained.

PlanetJ provides a CL command PJTOMCAT/STRTOMCAT that starts Tomcat. By default Tomcat is installed on the IFS in folder “tomcat5515”.        

1.  Verify that the 32 bit JVM is         installed. (or later version)

2.  Edit the tomcat start scripts in file: /tomcat5515/bin/catalina400.sh

3.  Change the “java_home”         variable to point to the desired JVM.         

export -s JAVA_HOME=/QOpenSys/QIBM/ProdData/JavaVM/jdk50/32bit

4. Save the script, restart Tomcat and test.