RFR: 8337511: Implement JEP 404: Generational Shenandoah (Experimental) [v8]

[William Kemper]

On Thu, 21 Nov 2024 20:10:20 GMT, William Kemper <wkemper at openjdk.org> wrote:

>> src/hotspot/share/gc/shenandoah/shenandoahMarkingContext.cpp line 64:
>> 
>>> 62:     }
>>> 63:   }
>>> 64:   return _mark_bit_map.is_bitmap_clear_range(start, end);
>> 
>> Comprehension check: this seems to bail out the moment it discovers an uncommitted slice. Does it really happen? More worryingly, if there is a mix of committed and uncommitted chunks, this method returns `true`, even if committed chunks are not actually clean?
>
> In all (3) usages of this method, the `start` and `end` are within the same region, so it isn't really iterating across regions. I'll rewrite it to handle this case more clearly.

https://bugs.openjdk.org/browse/JDK-8344797

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PR Review Comment: https://git.openjdk.org/jdk/pull/21273#discussion_r1852949662