RFR (S): 6490394: G1: Allow heap shrinking / memory unmapping after reclaiming regions during Remark

[Thomas Schatzl]

Hi Sanghon,

  thanks for your review.

On Mon, 2018-10-29 at 15:18 -0700, sangheon.kim at oracle.com wrote:
> Hi Thomas,
> 
> On 10/2/18 8:57 AM, Thomas Schatzl wrote:
> > Hi all,
> > 
> >   allow me to provide a fix for the oldest g1-specific open issue
> > on the bug tracker (from 2006 :)): resize the heap (eg. uncommit)
> > according to existing sizing policies at remark time.
> > 
> > It does exactly what the subject of the CR says.
> > 
> > [...]
> > The current work for "JDK-8204089: Timely Reducing Unused Committed
> > Memory" also depends on this change.
> > 
> > CR:
> > https://bugs.openjdk.java.net/browse/JDK-6490394
> > Webrev:
> > http://cr.openjdk.java.net/~tschatzl/6490394/webrev/
>  Looks good.
> Just minor nits so okay going with current webrev. And I don't need
> extra webrev if you accept it.

I changed the code as suggested. For reference (no need to re-review
it), the webrevs:

http://cr.openjdk.java.net/~tschatzl/6490394/webrev.0_to_1/ (diff)
http://cr.openjdk.java.net/~tschatzl/6490394/webrev.1/ (full)

Thanks again,
  Thomas