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

Soft references


Soft references are Java object classes that are to be treated specially by the garbage collector. Besides from standard "strong" references, there are soft references, weak references, and phantom references, all of which provide different levels of reachability than a standard reference. Soft and weak references are allowed to be garbage collected if memory is scarce, and are typically referenced by a wrapper object. A wrapper object is normally a Reference instance. Thus, soft and weak references may automatically be removed from a wrapper object by the GC if no other references exist. Phantom references, never reachable from their wrapper objects, can be used to implement finalization with safer semantics.