RFR: 8253434: Shenandoah: Cleanup ShenandoahRootScanner [v2]

[Zhengyu Gu]

On Mon, 21 Sep 2020 18:27:40 GMT, Roman Kennke <rkennke at openjdk.org> wrote:

>> src/hotspot/share/gc/shenandoah/shenandoahRootProcessor.cpp line 192:
>> 
>>> 190:
>>> 191: void ShenandoahRootScanner::roots_do(uint worker_id, OopClosure* oops) {
>>> 192:   CLDToOopClosure clds_cl(oops, ClassLoaderData::_claim_none);
>> 
>> Are you sure that we don't have to claim CLDs? How would the threads avoid doubly-marking CLDs?
>
> Actually it looks like the CLD closure is not used at all, or is it?

Right, we don't need to mark on-stack CLDs, concurrent mark CLDs should be sufficient.

Reran tests, still good.

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PR: https://git.openjdk.java.net/jdk/pull/286