RFR: 8374876: Epsilon: Convert to use Atomic<T>

[Aleksey Shipilev]

On Mon, 12 Jan 2026 10:12:08 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

> Epsilon uses AtomicAccess on volatile data. Convert it to use Atomic<T>. 
> 
> Additional testing:
>  - [x] Linux x86_64 server fastdebug, `gc/epsilon`, 100x

src/hotspot/share/gc/epsilon/epsilonMonitoringSupport.cpp line 120:

> 118: 
> 119: void EpsilonMonitoringSupport::mark_ready() {
> 120:   _ready.release_store(true);

Pre-existing: old code was using void return by accident. It does not look to be causing issues. (I am somewhat surprised this syntax is even allowed, but I guess it is useful for ordering pre-return statements.)

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PR Review Comment: https://git.openjdk.org/jdk/pull/29163#discussion_r2681615068