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

[Thomas Schatzl]

Hi,

On Thu, 2016-02-25 at 15:46 +0100, Mikael Gerdin wrote:
> 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

  looks good.

Looking at G1YoungRemSetSamplingThread::sample_young_list_rs_lenghts(),
why again are we starting the thread if adaptive young gen sizing is
disabled? But that's another (pre-existing) issue...

Thanks,
  Thomas