RFR: 8364343: Virtual Thread transition management needs to be independent of JVM TI [v3]

[Patricio Chilano Mateo]

On Wed, 26 Nov 2025 07:29:37 GMT, David Holmes <dholmes at openjdk.org> wrote:

>> I’d prefer to leave it as a plain store to avoid the unnecessary extra fence.
>
> But it isn't then an atomic update.

Only the disablers write to this counter while holding `VThreadTransition_lock` (verified in the assert above). But we still need to use `AtomicAccess` for the store because it can be concurrently read by the virtual thread.

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/28361#discussion_r2566654448