RFR (S) 8246100: Shenandoah: walk roots in more efficient order

[Aleksey Shipilev]

On 6/1/20 9:26 PM, Zhengyu Gu wrote:
> Wait, should we process CLDG early? CLD likely uneven, e.g. boot class 
> loader may take a lot longer than others.

It is not uneven in my tests. But even if it is, we want to do CLDG before thread/code roots, which
is what the patch does. With 8246097, it would be moved to the "lightweight/limited" block before.

> On 6/1/20 3:03 PM, Zhengyu Gu wrote:
>> Looks good in general. But not sure why call vm/weak/dedup roots limited 
>> parallel, I think they are fully parallel.

Yes. But they are also lightweight, that's what block does: both lightweight or limited-parallel.

>>> Webrev:
>>>    https://cr.openjdk.java.net/~shade/8246100/webrev.02/

-- 
Thanks,
-Aleksey