Java GC Tutorials - Herong's Tutorial Examples - v1.12, by Herong Yang
Tenured Generation Collection - Major GC
This section describes basic steps of a Tenured Generation Collection, also called a Major GC, which uses a simple 3-step Mark-Sweep-Compact algorithm on the entire Tenured Generation.
The basic algorithm used in Major GC is called Mark-Sweep-Compact, which consists of 3 steps:
- Mark - Identify which objects are still live in the Tenured Generation and mark them.
- Sweep - Identify and remove garbage by sweeping over the entire Tenured Generation.
- Compact - Move live objects towards the beginning of the generation to combine fragmented free spaces into a single contiguous chunk at the end of the generation.
The Mark-Sweep-Compact algorithm is very straightforward as illustrated in the picture below:
Table of Contents
Heap Memory Area and Size Control
JVM Garbage Collection Logging
►Introduction of Garbage Collectors
JVM Memory Manager - Garbage Collector
Generational Garbage Collection in HotSpot
Young Generation Collection - Minor GC
Young Generation Collectors - Serial, PS, ParNew, G1
►Tenured Generation Collection - Major GC
Tenured Generation Collectors - Serial, ParOldGen, CMS, G1
Collector Combinations: Serial, Parallel, Concurrent, G1, Z
Serial Collector - "+XX:+UseSerialGC"
Parallel Collector - "+XX:+UseParallelGC"
Concurrent Mark-Sweep (CMS) Collector - "+XX:+UseConcMarkSweepGC"
Garbage First (G1) Collector - "+XX:+UseG1GC"
The Z Garbage Collector (ZGC) - "+XX:+UseZGC"
Object References and Garbage Collection
Garbage Collection Performance Test Program
Performance Tests on Serial Collector
Performance Tests on Parallel collector
Performance Tests on Concurrent collector
Performance Tests on G1 collector