Java® Performance Companion

1. Garbage First Overview

This chapter is an introduction to the Garbage First (or G1) garbage collector (GC) along with a historical perspective on the garbage collectors in the Java HotSpot Virtual Machine (VM), hereafter called just HotSpot, and the reasoning behind G1’s inclusion in HotSpot. The reader is assumed to be familiar with basic garbage collection concepts such as young generation, old generation, and compaction. Chapter 3, “JVM Overview,” of the book Java™ Performance [1] is a good source for learning more about these concepts.

Serial GC was the first garbage collector introduced in HotSpot in 1999 as part of Java Development Kit (JDK) 1.3.1. The Parallel and Concurrent Mark Sweep collectors were introduced in 2002 as part of JDK ...