Chapter 7: Using the Geronimo Debug Console and jconsole

Overview

When things do not work as expected, you need tools that you give you the inside information to effectively troubleshoot and resolve problems. While the deployer goes to some length to display running modules and state information, it does not currently provide detailed information on most components residing in a Geronimo server instance.

To obtain the low-level detail information on the components that comprise a Geronimo server, you will need a secret troubleshooting tool. This little known tool has existed since the very early days of Geronimo Milestone 2, and it is aptly named the Geronimo debug console. While all administrators are familiar with the graphical Web console found with Geronimo Milestone 5 release and beyond, fewer have ever heard of the debug console.

This chapter introduces you to this very useful tool, where it is located, how to start it, and, most importantly, how to use it.

The architecture of the debug console is examined. As a prerequisite, you need to understand the basis technology that the debug console is built upon, including the following:

• Java Management Extension (JMX)

• JSR-77 J2EE management

This chapter provides an overview of JMX, as well as how it relates to JSR-77 and Geronimo. Key concepts in JSR-77 are covered, and their relevance to the debug console is revealed.

You will get some hands-on practice troubleshooting an actual deployment. A step-by-step walkthrough of a troubleshooting session with an actual application is included. You will also:

• Learn the steps involved in general troubleshooting

• Understand basic log analysis

• Be able to use the debug console to obtain low-level component information to assist you in troubleshooting

By the end of this chapter, you should be familiar with the operations of the debug console, and should be comfortable in using it to troubleshoot deployments in Geronimo.

For readers who are running Geronimo under JDK 1.5, the jconsole JMX tool (a part of the JDK) can also be used to monitor and troubleshoot Geronimo. Coverage of how to use jconsole is provided side-by-side with the Geronimo debug console discussion.