RFR: 8368251: Parallel: Refactor lgrp_id used in MutableNUMASpace [v2]

[Joel Sikström]

On Mon, 22 Sep 2025 12:25:53 GMT, Joel Sikström <jsikstro at openjdk.org> wrote:

>> Joel Sikström has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Don't set lgrp_id on Windows since we don't support NUMA there
>
> src/hotspot/os/windows/os_windows.cpp line 539:
> 
>> 537:   if (UseNUMA) {
>> 538:     thread->update_lgrp_id();
>> 539:   }
> 
> I'm a bit hesistant to remove this code from Windows since I have no way to test this. However, since we set `UseNUMA = false` early on initialization on Windows, Paralell should never start with NUMA enabled, so this code should effectively have no effect.

I decided to remove these two blocks from `os_windows.cpp`. Through some testing with logging, I see that UseNUMA is ergonomically set to false before any threads are created, so the code is never reached.

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PR Review Comment: https://git.openjdk.org/jdk/pull/27424#discussion_r2371624197