Hiroshi, One of our GC expert says:
These could be deadwood left behind in the heap because a compacting collection did not do a complete compaction of the heap (but left behind a "dense" prefix uncompacted and therefore with holes which were converted to look like in arrays). Those would appear as int arrays. Are these only int arrays or something else? Also, with the help of jhat if you can find the addresses of these objects are they kind of towards the early (lower address) part of the old generation? The deadwood is left behind because it may be too expensive to compact out that deadwood for very little gain (in terms of space freed).
I hope this helps.
Thanks, Swamy Hiroshi Yamauchi wrote:
Hi, I take a heap dump using the dumpHeap method described in http://java.sun.com/javase/6/docs/jre/api/management/extension/com/sun/management/HotSpotDiagnosticMXBean.html with the live parameter true and I see objects (int arrays) which have nothing in the "References to this object" section in the jhat output. This is on an openjdk6 b11 build. What could it mean? Thanks, Hiroshi
