JVM Tutorials - Herong's Tutorial Examples

∟Garbage Collection Tests

∟GC Test - Releasing Old vs. New Objects

This section provides a tutorial example on testing garbage collection by comparing performances between release old objects and new objects.

In the previous tests, objects were released from the tail of the list. So old objects were released first. To see if there are any differences between releasing old objects and new objects, I changed the code to use the objList.removeHead() method. 4 tests were conducted to compare with the previous tests:

java -Xms2m -Xmx8m GCTest 16 1 > head_16_01.out
java -Xms2m -Xmx8m GCTest 16 8 > head_16_08.out
java -Xms2m -Xmx8m GCTest 16 16 > head_16_16.out
java -Xms2m -Xmx8m GCTest 16 24 > head_16_24.out

The outputs were very similar to those using objList.removeTail() method. head_16_24.out also showed a memory crash at second 43.

Last update: 2003.

Table of Contents

 About This Book

 Download and Install Java SE 1.6 Update 2

 java.lang.Runtime Class - The JVM Instance

 java.lang.System Class - The Operating System

 ClassLoader Class - Class Loaders

 Class Class - Class Reflections

 Sun's JVM - Java HotSpot VM

 JRockit JVM 7.0 by BEA Systems

 JRockit JVM 8.0 by BEA Systems

 Memory Management Rules and Tests

►Garbage Collection Tests

 GCTest.java - Garbage Collection Test Program

 GC Test - Constant Memory Requirement

 GC Test - Periodical Memory Requirement

►GC Test - Releasing Old vs. New Objects

 GC Test - JDK 1.4.0 vs. JDK 1.3.1

 GC Test - Client vs. Server

 GC Test - JDK 1.6.0 vs. JDK 1.4.0

 Stack Overflow Tests

 Thread Testing Program and Result

 StringBuffer Testing Program and Result

 CDS (Class Data Sharing)

 Micro Benchmark Runner and JVM Options

 Micro Benchmark Tests on "int" Operations

 Micro Benchmark Tests on "long" Operations

 Micro Benchmark Tests in JIT Compilation Mode

 Micro Benchmark Tests on "float" and "double" Operations

 References

 PDF Printing Version