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

Thomas Schatzl thomas.schatzl at oracle.com
Thu Oct 4 15:39:26 UTC 2018


Hi,

On Thu, 2018-10-04 at 14:12 +0200, Stefan Johansson wrote:
> 
> On 2018-10-02 17:57, 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 feature is enabled by default - I did not see any reason to
> > disable it as the functionality seems to actually be what would be
> > expected of the concurrent cycle (as it mirrors the functionality
> > of a full gc).
> > 
> > Needs the change for JDK-8071913 currently out for review applied
> > to work (i.e. not crash after uncommit).
> > 
> > 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 great!

Thanks for your review.

Thanks,
  Thomas



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