RFR JDK-8060017 G1: Report heap sizing time

[Eric Caspole]

Hi Thomas, I have a couple questions below on your comments so I can see 
how to proceed -
Thanks,
Eric


On 10/14/2015 05:17 AM, Thomas Schatzl wrote:
> Hi Eric,
>

>
> some comments:
>   - the change only covers gathering timing numbers for expansion at the
> end of GC. Expansion may also occur during GC when the space used for
> evacuation is not sufficient any more.
> Not sure if that is intended, but the CR itself does not indicate that.
>
> If you think gathering information about time to expand during gc is out
> of scope of this CR (that's fine, it was me who suggested that), please
> consider adapting the CR and create a new one for tracking the expansion
> time during Object Copy.

I see what you mean here but I was not intending to add parallel Object 
Copy expand time here with the way I understood this CR. I'll create a 
new CR for recording the parallel Object Copy expand time indicated as a 
sort of sub-timing of Object Copy.

>
>   - please add the verification for this log message to the
> TestGCLogMessages test.

OK.

>
>   - maybe a better name for this phase that indicates that it is only
> about expansion at the end of the GC could be found?

That is a good idea if later on Object Copy expand time is shown too.

>
>   - I do not think it is a good idea to record heap expansion time during
> full GC. The PhaseTimes data structure is otherwise only filled in
> during young gc, so it's just confusing. (In G1CollectedHeap::
> resize_if_necessary_after_full_collection()).

Do you mean you don't want to record/display the expand time at all from 
there or just not record it using the PhaseTimes at that point? It seems 
like you would still want to show the expand time even for full gc, why not?

>
> Thanks,
>    Thomas
>
>