1076/800/80MB Test on HotSpot Client 1.7

JVM Tutorials - Herong's Tutorial Examples

∟1076/800/80MB Test on HotSpot Client 1.7

This chapter provides tutorial notes and example codes on garbage collection. Topics include garbage collection test program - GCTest2.java; comparisons between HotSpot 1.7.0, HotSpot 1.6.0 and JRockit R28.2.7.

For the next round of tests, I want to increase the memory usage of my test program to see the impact of JVM.

In the first test, I raised the base and fluctuating memory usages to 800MB and 80MB with 1.7.0_45 on my Windows 7 system which has about 1700 available physical memory.

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

>\Progra~1\java\jdk1.7.0_45\bin\java -Xmx1076m GCTest2 1280 640 64
Test parameters:
   Object size: 1280KB
   Initial objects and data size: 640, 819200KB
   Added objects and data size: 64, 81920KB
Time  Total  Free  Used  Free  Total  Act.  Dead  Over
sec.   Mem.  Mem.  Mem.    %.   Obj.  Obj.  Obj.  Head
1  1065152  163740  901412  15%  901120  819200   81920  292
2  1065152   81819  983333   7%  983040  819200  163840  293
3  1065152  163744  901408  15%  901120  819200   81920  288
5  1065152   81823  983329   7%  983040  819200  163840  289
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)

Too bad. HotSpot Client 1.7.0_45 crashed almost immediately, with -Xmx1076m.

However, when I added 1MB to the total memory, -Xmx1077m, the JVM was able to continue without any issues:

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

>\Progra~1\java\jdk1.7.0_45\bin\java -Xmx1077m GCTest2 1280 640 64
Test parameters:
   Object size: 1280KB
   Initial objects and data size: 640, 819200KB
   Added objects and data size: 64, 81920KB
Time    Total    Free     Used  Free  Total    Act.    Dead    Over
sec.     Mem.    Mem.     Mem.    %.   Obj.    Obj.    Obj.    Head
   1  1067136  165724   901412  15%  901120  819200   81920     292
   2  1067136   83803   983333   7%  983040  819200  163840     293
   3  1067136    1877  1065259   0%  901120  819200   81920  164139
   4  1067136   83807   983329   7%  901120  819200   81920   82209
   5  1067136    1886  1065250   0%  983040  819200  163840   82210
   7  1067136    1886  1065250   0%  901120  819200   81920  164130
   8  1067136   83808   983328   7%  901120  819200   81920   82208
   9  1067136    1886  1065250   0%  983040  819200  163840   82210
  10  1067136    1888  1065248   0%  901120  819200   81920  164128
  12  1067136   83810   983326   7%  901120  819200   81920   82206
  13  1067136    1886  1065250   0%  983040  819200  163840   82210
  14  1067136    1887  1065249   0%  901120  819200   81920  164129
  15  1067136   83803   983333   7%  901120  819200   81920   82213
  16  1067136    1876  1065260   0%  983040  819200  163840   82220
  18  1067136    1873  1065263   0%  901120  819200   81920  164143
  19  1067136   83810   983326   7%  901120  819200   81920   82206
  20  1067136    1841  1065295   0%  983040  819200  163840   82255
  22  1067136    1884  1065252   0%  902400  819200   83200  162852
  23  1067136   83810   983326   7%  902400  819200   83200   80926
  24  1067136    1842  1065294   0%  984320  819200  165120   80974
  25  1067136    1884  1065252   0%  902400  819200   83200  162852
  27  1067136   83810   983326   7%  902400  819200   83200   80926
  28  1067136    1842  1065294   0%  984320  819200  165120   80974
  29  1067136    1884  1065252   0%  902400  819200   83200  162852
  30  1067136   77921   989215   7%  902400  819200   83200   86815
  32  1067136   83811   983325   7%  902400  819200   83200   80925
  33  1067136    1884  1065252   0%  984320  819200  165120   80932
  34  1067136    1884  1065252   0%  902400  819200   83200  162852
  35  1067136   83810   983326   7%  902400  819200   83200   80926
  36  1067136    1841  1065295   0%  984320  819200  165120   80975
  38  1067136    1884  1065252   0%  902400  819200   83200  162852
  39  1067136   83810   983326   7%  902400  819200   83200   80926
  40  1067136    1842  1065294   0%  984320  819200  165120   80974
  41  1067136    1884  1065252   0%  902400  819200   83200  162852
  43  1067136   83810   983326   7%  902400  819200   83200   80926
  44  1067136    1842  1065294   0%  984320  819200  165120   80974
  45  1067136    1884  1065252   0%  902400  819200   83200  162852
  47  1067136   73568   993568   6%  902400  819200   83200   91168
  48  1067136   83811   983325   7%  902400  819200   83200   80925
  49  1067136    1882  1065254   0%  984320  819200  165120   80934
  50  1067136    1884  1065252   0%  902400  819200   83200  162852
...
 267  1067136   83820   983316   7%  906240  819200   87040   77076
 268  1067136    1851  1065285   0%  988160  819200  168960   77125
 270  1067136    1893  1065243   0%  906240  819200   87040  159003

Conclusion, HotSpot Client JVM 1.7.0_45 requires more than 1076MB to run a program that has a 800MB base memory usage plus 80MB fluctuating memory usage with object size of 1.25MB.

Last update: 2014.

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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