RFR: JDK-8216973: Shenandoah: Kick up cleanup phases in the right places
rkennke at redhat.com
Mon Jan 14 11:46:40 UTC 2019
>> In Shenandoah, we currently start cleanup phase when we dive into
>> concurrent evacuation (and only then), and after the cycle
>> (unconditionally). However, we only create trashed regions in final-mark
>> (immediate garbage and/or garbage from previous cycle), and might skip
>> evacuation altogether, and may not actually create trash at end of cycle
>> if we merge update-refs onto subsequent concurrent-mark. Let's start
>> cleanups where we actually need them: once unconditionally before
>> conc-evac and once after final-update-refs.
> The intent for the patch is okay.
> I think comments need to be updated, for example:
> After final-mark:
> // Final mark might have reclaimed some immediate garbage, kick cleanup to reclaim
> // the space. This would be the last action if there is nothing to evacuate.
> After update-refs:
> // Update references freed up collection set, kick the cleanup to reclaim the space.
>> Also, should this go into JDK12?
> I think this is the minor performance enhancement, and as such it should be deferred until first
> 12u. So, let's push this to jdk/jdk, let it be tested, and then we'll do the backport to
> jdk-updates/jdk12u, when that arrives.
Alright. I will push this:
to jdk/jdk then.
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