Packed with practical examples, this book looks at a different aspect of performance tuning in each chapter and shows the reader how to apply them to their existing Java applications. Written to version 5.1, this book also has information about the upcoming 6.0 release and how you can upgrade your existing applications. This book is for Java architects who design and configure Enterprise applications. It is great for Java developers who want to get into the inner details of the application server and of the correct tuning methodology. Application testers will also find this book useful as they will learn how to monitor the performance of the middleware with the correct instruments.
This book is full of practical advices on how to tune various components of your JBoss AS tech stack in order to maximize its throughput and scalability. It does not go into too much detail of describing the process however it provides pretty decent rationale of why you would want to touch each piece. I highly recommend it as a technical workbook (or cheat sheet) companion to Pro Java EE 5 Performance Management and Optimization which provides more theoretical background on the process.