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Intro(HSDB) #

-XX:-UseCompressedOopsoops: ordinary object pointer，普通对象指针压缩，例如Object o = new Object();其中o就是个指向new Object()对象的指针，o在指针压缩前占用8个字节，在指针压缩后占用4个字节。
-XX:-UseCompressedClassPointers压缩Klass Pointer，压缩前8个字节，压缩后4个字节。

sudo java -cp $JAVA_HOME/lib/sa-jdi.jar sun.jvm.hotspot.HSDB

Reference #

• https://github.com/openjdk/jdk/blob/jdk8-b120/hotspot/agent/src/share/classes/sun/jvm/hotspot/HSDB.java
• https://openjdk.org/groups/hotspot/docs/Serviceability.html#bsa
• https://docs.oracle.com/en/java/javase/11/tools/jhsdb.html#GUID-0345CAEB-71CE-4D71-97FE-AA53A4AB028E
• https://github.com/openjdk/jdk/tree/jdk8-b120/hotspot/agent/doc #下面站点可以渲染里面的html.
  1. https://htmlpreview.github.io/?https://github.com/openjdk/jdk/blob/jdk8-b120/hotspot/agent/doc/index.html
  2. https://svn.netlabs.org/repos/java/trunk/openjdk/hotspot/agent/doc/index.html