RFR: 8355627: Don't use ThreadCritical for EventLog list [v2]

[Martin Doerr]

On Wed, 30 Apr 2025 20:33:59 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

>> src/hotspot/share/utilities/events.cpp line 58:
>> 
>>> 56:     old_head = Atomic::load(&Events::_logs);
>>> 57:     _next = old_head;
>>> 58:   } while (Atomic::cmpxchg(&Events::_logs, old_head, this, memory_order_relaxed) != old_head);
>> 
>> I don't think it is safe to use `memory_order_relaxed` order if events are added after JVM enters multi-thread mode.
>
> Thanks for this. I didn't know why Aleksey suggested it.  I'll remove it.

Maybe @shipilev meant `memory_order_release`? Anyway, I guess we don't need to optimize it.

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PR Review Comment: https://git.openjdk.org/jdk/pull/24954#discussion_r2069432209