Book Image

Oracle JRockit: The Definitive Guide

Book Image

Oracle JRockit: The Definitive Guide

Overview of this book

Oracle JRockit is one of the industry’s highest performing Java Virtual Machines. Java developers are always on the lookout for better ways to analyze application behavior and gain performance. As we all know, this is not as easy as it looks. Welcome to JRockit: The Definitive Guide.This book helps you gain in-depth knowledge of Java from the JVM’s point of view. We will explain how to write code that works well with the JVM to gain performance and scalability. Starting with the inner workings of the JRockit JVM and finishing with a thorough walkthrough of the tools in the JRockit Mission Control suite, this book is for anyone who wants to know more about how the JVM executes your Java application and how to profile for better performance.
Table of Contents (23 chapters)
Oracle JRockit
Credits
Foreword
About the Authors
Acknowledgement
About the Reviewers
Preface
12
Using the JRockit Management APIs
Bibliography
Glossary
AST
CAS
HIR
IR
JFR
JMX
JRA
JSR
LIR
MD5
MIR
PDE
RCP
SWT
TLA
Index

Code generation strategies


There are several ways of executing bytecode in a JVM, from just emulating the bytecode in a pure bytecode interpreter to converting everything to native code for a particular platform.

Pure bytecode interpretation

Early JVMs contained only simple bytecode interpreters as a means of executing Java code. To simplify this a little, a bytecode interpreter is just a main function with a large switch construct on the possible opcodes. The function is called with a state representing the contents of the Java evaluation stack and the local variables. Interpreting a bytecode operation uses this state as input and output. All in all, the fundamentals of a working interpreter shouldn't amount to more than a couple of thousand lines of code.

There are several simplicity benefits to using a pure interpreter. The code generator of an interpreting JVM just needs to be recompiled to support a new hardware architecture. No new native compiler needs to be written. Also, a native...