RFR (S/M): 8222492: G1 unnecessarily scans remembered set cards for regions that already have been evacuated

[Thomas Schatzl]

Hi Kim,

  thanks for your review.

On Thu, 2019-05-16 at 18:45 -0400, Kim Barrett wrote:
> On Apr 26, 2019, at 8:27 AM, Thomas Schatzl <
> thomas.schatzl at oracle.com> wrote:
> > CR:
> > https://bugs.openjdk.java.net/browse/JDK-8222492
> > Webrev:
> > http://cr.openjdk.java.net/~tschatzl/8222492/webrev/
> > Testing:
> > hs-tier1-5, running the crashing test of JDK-8222426 for 5k times
> > without failures (the crash has an occurrence of 1-2 times/1000
> > runs).
> > 
> > Thanks,
> >  Thomas
> > 
> 
> Looks good.
> 
> One minor nit:
> 
> src/hotspot/share/gc/g1/g1OopClosures.inline.hpp
>  190   // Entries in the optional collection set may become to be
> located in the collection
>  191   // set during incremental collection of the old generation.
> 
> That comment needs some fixing.
> 

I changed the comment to the following and refreshed the webrev:

  // Entries in the optional collection set may start to originate from
the collection
  // set after one or more increments. In this case, previously
optional regions
  // became actual collection set regions. Filter them out here.

Thanks,
  Thomas