RFR: 8252141: Rename G1YoungRemSetSamplingThread to better reflect its purpose

[Kim Barrett]

> On Aug 24, 2020, at 5:36 PM, stefan.johansson at oracle.com wrote:
> 
> Hi,
> 
> Please review this rename of the G1 Young RemSet Sampling thread.
> 
> Webrev: http://cr.openjdk.java.net/~sjohanss/8252141/00/
> JBS: https://bugs.openjdk.java.net/browse/JDK-8252141
> 
> Summary
> The G1YoungRemSetSamplingThread does more than just remset sampling, it is also responsible for the scheduling of periodic GCs. Going forward even more taslks will likely be added to this thread and it should be renamed. The proposal in this patch is to rename it to G1ServiceThread.
> 
> It also includes renaming some members and other related functions.
> 
> Testing
> Mach5 tier1-3
> 
> Thanks,
> Stefan

Generally looks good.

src/hotspot/share/gc/g1/g1ServiceThread.hpp
  30 // The G1ServiceThread is used to do a number of different task:

Pluralize "task"

Also add "periodically", as in "used to periodically do".

I also noticed that G1ConcRefinementServiceIntervalMillis is kind of
misnamed and described, though with the change to "ServiceThread"
naming it's actually less poorly named than previously.

Changing the name is a bit of a pain, since it's a product option.
But the description should be fixed.