RFR (XXS): 8233997: Some members of HeapRegion are not cleared in HeapRegion::hr_clear()

[Kim Barrett]

> On Nov 12, 2019, at 10:23 AM, Thomas Schatzl <thomas.schatzl at oracle.com> wrote:
> 
> Hi all,
> 
>  can I get reviews for this small change that fixes some reinitialization problem of HeapRegions with the young remset sampling thread?
> 
> So the young remset sampling thread recalculates young gen remset sizes, and it happens that without this fix it may read the (old) remset size of the previous use of a given young gen region (also because of JDK-8233998).
> 
> The fix is to properly clear the remaining members not cleared yet in hr_clear.
> 
> CR:
> https://bugs.openjdk.java.net/browse/JDK-8233997
> Webrev:
> http://cr.openjdk.java.net/~tschatzl/8233997/webrev/
> Testing:
> hs-tier1-5 with other similar patches, specjvm2008 specjvm.validation with -XX:G1ConcRefinementServiceIntervalMillis=1 (that one causes issues quickly if you assert that the remembered sets for regions only grows)
> 
> Thanks,
>  Thomas

Looks good.