Created
March 14, 2012 18:09
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Getting the HeapOopSize through sun.misc.Unsafe. Refer to http://mail.openjdk.java.net/pipermail/hotspot-compiler-dev/2012-March/007445.html
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| D:\experiment>java -version | |
| java version "1.6.0_30" | |
| Java(TM) SE Runtime Environment (build 1.6.0_30-b12) | |
| Java HotSpot(TM) 64-Bit Server VM (build 20.5-b03, mixed mode) | |
| D:\experiment>groovysh | |
| Groovy Shell (1.8.4, JVM: 1.6.0_30) | |
| Type 'help' or '\h' for help. | |
| --------------------------------------------------------------------------------------------------- | |
| groovy:000> sun.misc.Unsafe.theUnsafe.arrayIndexScale(Object[].class) | |
| ===> 4 | |
| groovy:000> sun.misc.Unsafe.theUnsafe.arrayBaseOffset(Object[].class) | |
| ===> 16 | |
| groovy:000> quit | |
| D:\experiment>set JAVA_OPTS=-XX:-UseCompressedOops | |
| D:\experiment>groovysh | |
| Groovy Shell (1.8.4, JVM: 1.6.0_30) | |
| Type 'help' or '\h' for help. | |
| --------------------------------------------------------------------------------------------------- | |
| groovy:000> sun.misc.Unsafe.theUnsafe.arrayIndexScale(Object[].class) | |
| ===> 8 | |
| groovy:000> sun.misc.Unsafe.theUnsafe.arrayBaseOffset(Object[].class) | |
| ===> 24 | |
| groovy:000> quit | |
| D:\experiment> |
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