RFR (S): Reset bitmaps in MarkCompact should use parallel threads

[Aleksey Shipilev]

On 11/02/2016 08:09 PM, Aleksey Shipilev wrote:
> http://cr.openjdk.java.net/~shade/shenandoah/markcompact-par-reset-bitmaps/webrev.01/

I have a question! When clearing the prev bitmap, should we go up to...

a) region->top_prev_mark_bitmap(): clearing only the set bits?

http://cr.openjdk.java.net/~shade/shenandoah/markcompact-par-reset-bitmaps/webrev.01/

b) region->top(): clearing the entire region map defensively?

http://cr.openjdk.java.net/~shade/shenandoah/markcompact-par-reset-bitmaps/webrev.02/

Thanks,
-Aleksey