RFR (M) JDK-8150390: Move rs length sampling data to the sampling thread

[Jesper Wilhelmsson]

Looks good!
/Jesper

Den 25/2/16 kl. 15:46, skrev Mikael Gerdin:
> Hi all,
>
> The G1 Young RemSet Sampling Thread iterates over the young regions to estimate
> the remembered set sizes of the young gen in order to tweak the young gen size
> between gcs.
>
> All the iteration and the state related to this has been stored in the YoungList
> class for some strange reason. The state is actually only ever needed in
> G1YoungRemSetSamplingThread::sample_young_list_rs_lengths()
> so I've moved all of it there.
> I also modified revise_young_list_target_length_if_necessary to receive the new
> rs length sample as a parameter instead of picking it up from the YoungList class.
>
> Bug: https://bugs.openjdk.java.net/browse/JDK-8150390
> Webrev: http://cr.openjdk.java.net/~mgerdin/8150390/webrev.0
> Testing: Local GC test suite and JPRT
>
> Thanks
> /Mikael