Collection set is empty -> conc mark cancelled (+ RFR)

[Aleksey Shipilev]

On 11/24/2016 02:59 PM, Roman Kennke wrote:
>> OTOH, it is bad to punish the garbage-free application with full GCs
>> here. Even heuristics would not save us here: "aggressive" would
>> trigger
>> mark, discover no garbage, and do the full GC nevertheless.
> 
> If there is no garbage, I'd say carry on, skip evacuation (or let it
> run with empty, which should be fast).

Yes, let's just move on then:
  http://cr.openjdk.java.net/~shade/shenandoah/emptycset-concgc/webrev.01/

Thanks,
-Aleksey