RFR: 8264718: Shenandoah: enable string deduplication during root scanning [v2]

[Aleksey Shipilev]

On Wed, 7 Apr 2021 12:11:18 GMT, Zhengyu Gu <zgu at openjdk.org> wrote:

>> Shenandoah used to scan roots at pauses, so it deliberately disables string deduplication during root scanning to avoid extra pause times.
>> 
>> Now, Shenandoah scans roots in concurrent phase, it is no longer a concern, we should enable it.
>> 
>> Test:
>> - [x] hotspot_gc_shenandoah
>
> Zhengyu Gu has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Removed excessive empty lines

Looks fine, with a minor nit. Fix it before push.

src/hotspot/share/gc/shenandoah/shenandoahSTWMark.cpp line 132:

> 130: void ShenandoahSTWMark::mark_roots(uint worker_id) {
> 131:   if (ShenandoahStringDedup::is_enabled()) {
> 132:     ShenandoahInitMarkRootsClosure<ENQUEUE_DEDUP>  init_mark(task_queues()->queue(worker_id));

Excess space here and on the other branch, between `<ENQUEUE_DEDUP>` and `init_mark`.

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Marked as reviewed by shade (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/3348