640/400/40MB Test on HotSpot Client 1.6

JVM Tutorials - Herong's Tutorial Examples

∟640/400/40MB Test on HotSpot Client 1.6

This section provides a tutorial example on running GCTest2.java on HotSpot Client JVM 1.6.0_45 with 640MB memory limit and a 400MB base plus 40MB fluctuating memory usage with object size of 1.25MB.

As a comparison, I ran GCTest2.java with the same parameters on HotSpot Client 1.6.0_45 my Windows 7 system:

>\Progra~1\java\jdk1.6.0_45\bin\javac GCTest2.java

>\Progra~1\java\jdk1.6.0_45\bin\java -Xmx640m GCTest2
Test parameters:
   Object size: 1280KB
   Initial objects and data size: 320, 409600KB
   Added objects and data size: 32, 40960KB
Time   Total    Free    Used  Free  Total    Act.    Dead    Over
sec.    Mem.    Mem.    Mem.    %.   Obj.    Obj.    Obj.    Head
   1  633536  182807  450729  28%  450560  409600   40960     169
   2  633536  141849  491687  22%  450560  409600   40960   41127
   3  633536  100888  532648  15%  491520  409600   81920   41128
   4  633536   59928  573608   9%  532480  409600  122880   41128
   5  633536   18967  614569   2%  573440  409600  163840   41129
   7  633536    7448  626088   1%  450560  409600   40960  175528
   8  633536  141860  491676  22%  450560  409600   40960   41116
   9  633536  100900  532636  15%  491520  409600   81920   41116
  10  633536   59939  573597   9%  532480  409600  122880   41117
  11  633536   18971  614565   2%  573440  409600  163840   41125
  12  633536   18976  614560   2%  450560  409600   40960  164000
  13  633536  141864  491672  22%  450560  409600   40960   41112
  14  633536  100900  532636  15%  491520  409600   81920   41116
  15  633536   59940  573596   9%  532480  409600  122880   41116
  16  633536   18976  614560   2%  573440  409600  163840   41120
  18  633536   18979  614557   2%  450560  409600   40960  163997
  19  633536  141866  491670  22%  450560  409600   40960   41110
  20  633536  100903  532633  15%  491520  409600   81920   41113
  21  633536   59939  573597   9%  532480  409600  122880   41117
  22  633536   18976  614560   2%  573440  409600  163840   41120
  23  633536  182827  450709  28%  450560  409600   40960     149
  24  633536  141865  491671  22%  491520  409600   81920     151
  25  633536  100902  532634  15%  532480  409600  122880     154
  26  633536   59938  573598   9%  573440  409600  163840     158
  27  633536   18975  614561   2%  614400  409600  204800     161
Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
        at GCTest2$MyObject.<init>(GCTest2.java:70)
        at GCTest2.myTest(GCTest2.java:37)
        at GCTest2.main(GCTest2.java:22)

Conclusion, HotSpot Client JVM 1.7.0_45 requires more than 640MB to run a program that has a 400MB base memory usage plus 40MB fluctuating memory usage with object size of 1.25MB. Basically, the JVM requires more than 200MB to manage dead objects and other system tasks.

Last update: 2014.

Table of Contents

About This Book

Downloading and Installing JDK 1.8.0 on Windows

Downloading and Installing JDK 1.7.0 on Windows

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 28.2.7 by Oracle Corporation

JVM Runtime Data Areas