RFR: 8376126: G1: Convert remaining volatiles in G1ConcurrentMark to Atomic<T>

[Ivan Walulya]

On Thu, 22 Jan 2026 16:36:08 GMT, Thomas Schatzl <tschatzl at openjdk.org> wrote:

> Hi all,
> 
>   please convert remaining volatile declarations in `G1ConcurrentMark` to use `Atomic<T>`. These volatiles are used to indicate concurrent phased access (like changing the variable in thread A, then reading the variable in thread B while A is dormant, or only ever updating it in one direction) where concurrency safety is provided by barriers between these phases. But there are also other cases)
> 
> The exception is `G1ConcurrentMark::_finger` that has apparently been overlooked in an earlier changes.
> 
> Testing: gha
> 
> Thanks,
>   Thomas

Marked as reviewed by iwalulya (Reviewer).

src/hotspot/share/gc/g1/g1ConcurrentMark.hpp line 679:

> 677:   uint completed_mark_cycles() const;
> 678: 
> 679:   bool has_aborted()      { return _has_aborted.load_relaxed(); }

Suggestion:

  bool has_aborted() { return _has_aborted.load_relaxed(); }

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PR Review: https://git.openjdk.org/jdk/pull/29368#pullrequestreview-3697312733
PR Review Comment: https://git.openjdk.org/jdk/pull/29368#discussion_r2721051786