GC interface update

[Per Liden]

Hi Roman,

On 2017-04-12 16:46, Roman Kennke wrote:
> I spent some more time working on the GC interface prototype and wanted
> to share it with you:
>
> http://cr.openjdk.java.net/~rkennke/gc-interface/webrev.02/
> <http://cr.openjdk.java.net/%7Erkennke/gc-interface/webrev.02/>
>
> Notable changes:
>
> - It's now based on JDK10 (specifically,
> http://hg.openjdk.java.net/jdk10/hs/hotspot changeset 12853:d276073fda85)
> - I focused on better CMS isolation:
>   - Most CMS specific stuff from GenCollectedHeap now resides in
> specific subclass CMSHeap
>   - Same for CardTableModRefBSForCTRS -> CMSBarrierSet
>   - Factored everything related to always_do_update_barrier_set into CMS
> subclasses

Good stuff. However, one thing I'm not quite comfortable with is the 
introduction of the GC class (and its sub classes). I don't quite see 
the purpose of this interface split-up between GC and CollectedHeap. I 
view CollectedHeap as _the_ interface (but yes, it needs some love), and 
as a result I think the the functions you've exposed in the GC class 
actually belongs in CollectedHeap.

cheers,
Per

>
> The JEP is still in 'submitted' state. Would be good to have it moved to
> 'candidate' at least, so that it gets a number?
>
> https://bugs.openjdk.java.net/browse/JDK-8163329
>
> Does anybody know a good place where I could put a whole forest to
> develop this in?
>
> As always, any feedback is welcome.
>
> Best regards,
> Roman
>