Table of Contents

Chapter 1: Garbage First Overview

Terminology

Parallel GC

Serial GC

Concurrent Mark Sweep (CMS) GC

Garbage First (G1) GC

References

Chapter 2: Garbage First Garbage Collector in Depth

Background

Garbage Collection in G1

The Young Generation

A Young Collection Pause

Object Aging and the Old Generation

Humongous Regions

A Mixed Collection Pause

Collection Sets and Their Importance

Remembered Sets and Their Importance

Concurrent Marking in G1 GC

Stages of Concurrent Marking

Evacuation Failures and Full Collection

References

 

Chapter 3: Garbage First Garbage Collector Performance Tuning

The Stages of a Young Collection

Young Generation Tunables

Concurrent Marking Phase Tunables

A Refresher on the Mixed Garbage Collection Phase

The Taming of a Mixed Garbage Collection Phase

Avoiding Evacuation Failures

Reference Processing

References

 

Chapter 4: The Serviceability Agent

What Is the Serviceability Agent?

Why Do We Need the SA?

SA Components

SA Binaries in the JDK

JDK Versions with Complete SA Binaries

How the SA Understands HotSpot VM Data Structures

SA Version Matching

The Serviceability Agent Debugging Tools

Core Dump or Crash Dump Files

Debugging Transported Core Files

System Properties for the Serviceability Agent

Environment Variables for the Serviceability Agent

JDI Implementation

Extending Serviceability Agent Tools

Serviceability Agent Plugin for VisualVM

Troubleshooting Problems Using the SA

 

Appendix: Additional HotSpot VM Command-Line Options of Interest

About the Author

Charlie Hunt, is a JVM Performance Engineer at Oracle where he works on the performance of Java SE, Java EE, Java HotSpot VM, and Java SE class libraries. He presents on Java performance at various events, including JavaOne, QCon, Velocity, and Dreamforce, and he coauthored Java Performance (Addison-Wesley, 2012).

Monica Beckwith is an independent performance consultant optimizing customer applications for server class systems running the Java Virtual Machine. She has worked with Java HotSpot VM optimising the JIT Compiler, the generated code, the JVM heuristics and garbage collection and collectors. Monica led Oracle’s Garbage First Garbage Collector performance team and was named a JavaOne Rock Star.

Poonam Parhar is a JVM Sustaining Engineer at Oracle, where her primary responsibility is to resolve customer-escalated problems against Oracle JRockit and Java HotSpot VMs. She loves debugging and troubleshooting problems, and is always focused on improving the serviceability and supportability of the JVM.

Bengt Rutisson is a JVM Engineer at Oracle, working in the HotSpot VM team. He has worked on garbage collections in JVMs for the past ten years, first with the Oracle JRockit VM and the last six years with the Java HotSpot VM. Bengt is an active participant in the OpenJDK project, with many contributions of features, stability fixes and performance enhancements.