Memory Footprint of JRockit R28.2.7

This section provides a tutorial example on how to check memory footprint of JRockit 6 R28.2.7 on Windows systems. JRockit has a much higher footprint than HotSpot.

The first thing I want to check on the JRockit JVM is the memory footprint of the virtual machine by using the following tutorial program:

 * Copyright (c) 2013,, All Rights Reserved.
class LongSleep2 {
   public static void main(String[] a) {
      Runtime rt = Runtime.getRuntime();
      System.out.println("Total memory: " + rt.totalMemory());
      System.out.println(" Free memory: " + rt.freeMemory());
      System.out.println(" Used memory: "
         + (rt.totalMemory()-rt.freeMemory()));
      try {Thread.sleep(1000*60*60);}
      catch (InterruptedException e) {}

Compile and run it on JRockit R28.2.7, I got this output:

>\Progra~1\java\jrockit-jdk1.6.0_45-R28.2.7-4.1.0\bin\javac \

>\Progra~1\java\jrockit-jdk1.6.0_45-R28.2.7-4.1.0\bin\java LongSleep2

Total memory: 67108864
 Free memory: 63434800
 Used memory: 3674064

As a comparison, compile and run the same program on HotSpot (JDK) 1.6.0 in another command window:



Total memory: 16252928
 Free memory: 15965056
 Used memory: 287872

Now run the same program again on HotSpot (JDK) 1.6.0 in "Server" mode in a third command window:

>\Progra~1\java\jdk1.6.0_45\bin\java -server

Total memory: 54919168
 Free memory: 54632104
 Used memory: 287064

The output shows that JRockit R28.2.7 has a much bigger footprint, 3,674KB, comparing to 287KB used by HotSpot 1.6.0.

While all 3 JVM instances are running, we can also compare their memory usages reported by the system Task Manager:

               Task Manager       Run Time Environment
JVM                  Memory     Total     Free    Used
-------------- ------------   -------  -------  ------
JRockit             16,780K   67,108K  63,434K  3,674K
HotSpot Client       3,488K   16,252K  15,965K    287K
HotSpot Server       3,776K   54,919K  54,632K    287K

It is interesting to see that the Task Manager reports much less message sizes than Runtime class methods. But it still also confirming that JRockit has a much bigger footprint comparing to HotSpot.

Table of Contents

 About This Book

 JVM (Java Virtual Machine) Specification

 Java HotSpot VM - JVM by Oracle/Sun

 java.lang.Runtime Class - The JVM Instance

 java.lang.System Class - The Operating System

 ClassLoader Class - Class Loaders

 Class Class - Class Reflections

 JVM Runtime Data Areas

 JVM Stack, Frame and Stack Overflow

 Thread Testing Program and Result

 CPU Impact of Multi-Thread Applications

 I/O Impact of Multi-Thread Applications

 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

 OpenJ9 by Eclipse Foundation

JRockit JVM 28.2.7 by Oracle Corporation

 What Is JRockit JVM?

 Downloading and Installing JRockit R28.2.7

 Running Java Programs on JRockit R28.2.7

Memory Footprint of JRockit R28.2.7

 What Is JRockit Mission Control?

 Running JRockit Mission Control

 What JRockit Management Console

 JRockit Management Console on HotSpot JVM

 Archived Tutorials


 Full Version in PDF/EPUB