RFR (S): Heap dump support

[Aleksey Shipilev]

On 12/12/2016 04:16 PM, Roman Kennke wrote:
> this would report evacuated objects twice, right? Maybe simply skip
> cset regions?

Right, I missed the double-counting here!

> Not sure we need to update references. Seems like extra unnecessary
> work. Calling code should do the appropriate read barriers, or receive
> opaque JNI handles.

Except that HeapDumper does not have read barriers, and does abominable things
like accessing field with naked (oop + field_offset). A little more safety for
"safe_*" iteration method would not hurt.


> I believe the straightforward way to implement this is to simply
> delegate to marked_object_iterate() but only for non-cset regions.

Right. A little less straightforward way is to reuse flagged
heap_region_iterate() for this. See:
  http://cr.openjdk.java.net/~shade/shenandoah/heapdump-support/webrev.02/

Thanks,
-Aleksey