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It has to be noted that on HotSpot the object header is only two words not three words like on J9. Basically Flags and Locks fit into one word on HotSpot wherea

It has to be noted that on HotSpot the object header is only two words not three words like on J9. Basically Flags and Locks fit into one word on HotSpot whereas they use two words on J9.

jcdavis 10y ago
Only on 32 bit IIRC, headers are 12 byte on 64 bit with CompressedOops (the default for heaps <32gb) and 16 bytes without. The bit layout of the markoop is here: http://hg.openjdk.java.net/jdk8/jdk8/hotspot/file/87ee5ee27509/src/share/vm/oops/markOop.hpp http://hg.openjdk.java.net/jdk8/jdk8/hotspot/file/87ee5ee275...
- needusername 10y ago
  You are correct.
PDoyle 10y ago
J9 has had one-word headers for years now. I think this article was already out of date in 2012 when it was published.
- needusername 10y ago
  That sounds interesting. Do you have source that you can share?
  - deleted 10y ago
    [deleted]