Outdated: 640/400/40MB Test on HotSpot Client 1.7

This section provides a tutorial example on running GCTest2.java on HotSpot Client JVM 1.7.0_45 with 640MB memory limit and a 400MB base plus 40MB fluctuating memory usage with object size of 1.25MB.

Here is my first test with GCTest2.java with HotSpot Client 1.7.0_45 and maximum memory of 640MB on my Windows 7 system:

>\Progra~1\java\jdk1.7.0_45\bin\javac GCTest2.java

>\Progra~1\java\jdk1.7.0_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  182776  450760  28%  450560  409600   40960     200
   3  633536  141817  491719  22%  450560  409600   40960   41159
   4  633536  100857  532679  15%  491520  409600   81920   41159
   5  633536   59896  573640   9%  532480  409600  122880   41160
   6  633536   18936  614600   2%  573440  409600  163840   41160
   7  633536    7417  626119   1%  450560  409600   40960  175559
   8  633536  141829  491707  22%  450560  409600   40960   41147
   9  633536  100868  532668  15%  491520  409600   81920   41148
  10  633536   59908  573628   9%  532480  409600  122880   41148
  11  633536   18939  614597   2%  573440  409600  163840   41157
  12  633536   18944  614592   2%  450560  409600   40960  164032
  14  633536  141833  491703  22%  450560  409600   40960   41143
  15  633536  100869  532667  15%  491520  409600   81920   41147
  16  633536   59908  573628   9%  532480  409600  122880   41148
  17  633536   18944  614592   2%  573440  409600  163840   41152
  18  633536   18947  614589   2%  450560  409600   40960  164029
  19  633536  141834  491702  22%  449280  409600   39680   42422
  20  633536  100872  532664  15%  490240  409600   80640   42424
  21  633536   59907  573629   9%  531200  409600  121600   42429
  22  633536   18945  614591   2%  572160  409600  162560   42431
  23  633536  182796  450740  28%  449280  409600   39680    1460
  25  633536  141833  491703  22%  490240  409600   80640    1463
  26  633536  100871  532665  15%  531200  409600  121600    1465
  27  633536   59906  573630   9%  572160  409600  162560    1470
  28  633536   18944  614592   2%  613120  409600  203520    1472
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)

I am very surprised to see OutOfMemoryError exception. Let's review the output to understand what happened in the JVM. Note that the output was reformatted with white spaces.

I repeated this test many times. "OutOfMemoryError" exception occurred about 70% of the time.

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: 2018.

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

Outdated Tutorials

 Outdated: GCTest2.java - Garbage Collection Test Program

Outdated: 640/400/40MB Test on HotSpot Client 1.7

 Outdated: 640/400/40MB Test on HotSpot Client 1.6

 Outdated: 640/400/40MB Test on JRockit 28.2

 Outdated: 441/400/40MB Test on JRockit 28.2

 Outdated: 1076/800/80MB Test on HotSpot Client 1.7

 Outdated: 1076/800/80MB Test on HotSpot Client 1.6

 Outdated: 1076/800/80MB Test on JRockit 28.2

 References

 Full Version in PDF/EPUB