RFR: 8255019: Shenandoah: Split STW and concurrent mark into separate classes [v27]

[Zhengyu Gu]

On Wed, 13 Jan 2021 15:03:24 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> src/hotspot/share/gc/shenandoah/shenandoahHeap.cpp line 2212:
>> 
>>> 2210:       if (point == _degenerated_mark) {
>>> 2211:         finish_mark();
>>> 2212:       }
>> 
>> So if we don't call `finish_mark`, do we ever call  `set_concurrent_mark_in_progress(false);` and `mark_complete_marking_context();`?
>
> This was not answered, and I don't see relevant follow-up changes. Is this a bug?

No, I don't think so.

For fall through case, STWMark sets both flags. 

For degen case, if we pass _degnerated_mark point, op_final_mark calls finish_mark to set them.

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PR: https://git.openjdk.java.net/jdk/pull/1009