RFR: 8367708: GenShen: Reduce total evacuation burden [v2]

[Kelvin Nilsen]

On Mon, 15 Sep 2025 23:58:27 GMT, William Kemper <wkemper at openjdk.org> wrote:

>> Kelvin Nilsen has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Respond to reviewer feedback
>
> src/hotspot/share/gc/shenandoah/shenandoahHeap.cpp line 1442:
> 
>> 1440:   assert(start->is_humongous_start(), "reclaim regions starting with the first one");
>> 1441: 
>> 1442:   // Cannot access humongous_obj->size() in case class has been unloaded
> 
> Why do we want to make two passes over the humongous object? I don't see why the original code needs to change or how this change is related to this PR?

There's a comment in the "new code" that we have to reclaim from the tail.  Otherwise assertion fails when printing region to trace log. 

I agree it is unclear how this relates to current PR.  I'll revert and see if something breaks.

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PR Review Comment: https://git.openjdk.org/jdk/pull/27278#discussion_r2353251364