RFR: 8335480: Only deoptimize threads if needed when closing shared arena [v3]

[Maurizio Cimadamore]

On Mon, 15 Jul 2024 12:00:31 GMT, Maurizio Cimadamore <mcimadamore at openjdk.org> wrote:

> When I remove the `has_scoped_access()` check before the deopt, I expect the `otherAccess` thread to be affected, but the effect isn't nearly as big as with the FFM thread. I think this is likely due to the `otherAccess` benchmark being less sensitive to optimization (i.e. it already runs fairly fast in the interpreter). I also tried using `MethodHandles::arrayElementGetter` for the access, but the numbers I got were pretty much the same:

To put this into perspective, once the underlying bug with reachability fences is addressed, then we should see the numbers for this benchmark align with the ones where you removed deopt completely (as we won't deopt threads that don't have the target arena in their oopmap)

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PR Comment: https://git.openjdk.org/jdk/pull/20158#issuecomment-2228353326