RFR: 8367013: Add Atomic<T> to package/replace idiom of volatile var plus AtomicAccess:: operations

[Andrew Haley]

On Wed, 24 Sep 2025 05:32:38 GMT, Kim Barrett <kbarrett at openjdk.org> wrote:

> Please review this change that adds the type `Atomic<T>`, to use as the type
> of a variable that is accessed (including writes) concurrently by multiple
> threads. This is intended to replace (most) uses of the current HotSpot idiom
> of declaring a variable `volatile` and accessing that variable using functions
> from the AtomicAccess class.
> https://github.com/openjdk/jdk/blame/528f93f8cb9f1fb9c19f31ab80c8a546f47beed2/doc/hotspot-style.md#L138-L147
> 
> Testing: mach5 tier1-6, GHA sanity tests

src/hotspot/share/gc/shared/stringdedup/stringDedupTable.cpp line 424:

> 422: StringDedup::Table::CleanupState* StringDedup::Table::_cleanup_state = nullptr;
> 423: bool StringDedup::Table::_need_bucket_shrinking = false;
> 424: Atomic<size_t> StringDedup::Table::_dead_count{};

Suggestion:

Atomic<size_t> StringDedup::Table::_dead_count;

This is not a function, is it?

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PR Review Comment: https://git.openjdk.org/jdk/pull/27462#discussion_r2374909050