heap dump

[Swamy Venkataramanappa]

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
>