JVM Garbage Collection Logging

Java 8 GC Tutorials - Herong's Tutorial Examples

∟JVM Garbage Collection Logging

This chapter provides tutorial notes and example codes on JVM options for garbage collection logging. Topics include a summary of logging options; examples of log messages for '-XX:+PrintGCDetails', '-XX:+PrintGCDateStamps', '-XX:+PrintGCDateStamps', 'PrintGCApplicationStoppedTime', etc.

Garbage Collection Demo Program

Garbage Collection Logging Options

"-XX:+PrintGC" - GC Logging Option for Short Messages

"-XX:+PrintGCDetails" - Option for Detailed GC Messages

"-XX:+PrintGCDateStamps" - Calendar Timestamp on GC Messages

"-XX:+PrintGCApplicationStoppedTime" - Application Pause Durations

"-XX:+PrintGCApplicationConcurrentTime" - Application Running Durations

"-XX:+PrintHeapAtGC" - Print Heap Summary per GC

"-XX:+PrintTenuringDistribution" - Tunuring Distribution

"-XX:+PrintReferenceGC" - Reference Counts per GC

"-XX:+PrintFlagsFinal" - Print JVM Options

Takeaways:

The Heap area memory management is done by the garbage collector, which allocates and deallocates data objects automatically for the Java application. The garbage collector (GC) also automatically collects dead objects to free up used memory.
The -XX:+PrintGCDetails option generates GC detail log messages helping us to know how well the garbage collector is doing its job.
The -XX:+PrintGCDateStamps option adds calendar timestamps for all GC log messages.
The -XX:+PrintGCApplicationStoppedTime option reports the duration of each application pause caused by GC or other JVM event.
The -XX:+PrintGCApplicationConcurrentTime option reports the duration of each period of application running without any pauses.
The -XX:+PrintHeapAtGC option prints heap usage summary before and after each GC.
The -XX:+PrintTenuringDistribution option prints a list of age groups and their sizes in the survivor space after each minor GC.
The -XX:+PrintReferenceGC option prints number of references processed for each reference type and time used to process them at each GC.

Table of Contents

About This Book

Heap Memory Area and Size Control

►JVM Garbage Collection Logging

Introduction of Garbage Collectors

Serial Collector - "+XX:+UseSerialGC"

Parallel Collector - "+XX:+UseParallelGC"

Concurrent Mark-Sweep (CMS) Collector - "+XX:+UseConcMarkSweepGC"

Garbage First (G1) Collector - "+XX:+UseG1GC"

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

Garbage Collection Performance Test Summary

Archived Tutorials

References

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