RFR (S): 8205426: Humongous continues remembered set does not match humongous start region one in Kitchensink

[Thomas Schatzl]

Hi all,

  can I have reviews for this fix that is scheduled for JDK 11?

Thanks,
  Thomas

On Tue, 2018-06-26 at 19:15 +0200, Thomas Schatzl wrote:
> Hi all,
> 
>   can I have reviews for this bug in keeping remembered sets
> consistent between HC and HS regions, causing crashes with
> verification?
> 
> The problem occurs during updating the remembered sets during the
> Remark pause. This process is parallel; it uses liveness information
> from marking to set the new remembered set states.
> 
> However during marking G1 attributes all liveness information of a
> humongous object to the HS region; if that liveness information has
> not been updated yet for HC regions, and another thread is
> responsible for determining that HC region's remembered set state,
> the new remembered set state of the HC region will get a state as the
> HS region.
> 
> The fix is to, for HC regions, just pass the liveness data of the HS
> region into the method that determines the new remembered set state.
> Further, in that latter method, make sure that the predicate for
> determining whether a region gets a remembered set assigned is
> completely disjoint for humongous and non-humongous regions.
> 
> CR:
> https://bugs.openjdk.java.net/browse/JDK-8205426
> Webrev:
> http://cr.openjdk.java.net/~tschatzl/8205426/webrev/
> Testing:
> new test case, hs-tier1-4,jdk-tier1-3
> 
> Thanks,
>   Thomas
>