CR 8005604: HPROF should report the actual instance size

[Alan Bateman]

On 29/12/2012 10:10, Aleksey Shipilev wrote:
> :
>
> Seems like that instance_size() method is used to populate both GC_CLASS
> and GC_INSTANCE. Would it be OK to push the VM-reported size to GC_CLASS
> only, and leave GC_INSTANCE intact?
>
I don't think it can be in either as the sizes in the HPROF dump are VM 
and padding independent. A few years back there was discussion about 
defining a new format or (better-still) API but it didn't happen. The 
only thing I can suggest for the short term would be to rev the HPROF 
format to define a new record that provides a better details on the 
sizes and layout. It's a slippery slope of course. In the mean-time, at 
least for the built-in heap dumper and the SA-based heap dumper, then 
the object ID is the oop so it's possible to deduce something.

-Alan