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

Garbage collection algorithms


All techniques for automatic memory management boil down to keeping track of which objects are being used by the running program, in other words, which objects are referenced by other objects that are also in use. Objects that are no longer in use may be garbage collected. We will use the terms live and in use interchangeably.

It is hard to exactly place garbage collection techniques in different categories. With the risk of drawing fire from the academic community, we will use the term "tracing garbage collection" for everything except reference counting. Tracing garbage collection means building a graph of live objects at a collection event and discarding unreachable ones. The only other kind of technique that we will cover is reference counting.

Reference counting

Reference counting is a memory management technique where the runtime keeps track of how many live objects point to a particular object at a given time.

When the reference count for an object decreases...