RFR: 8300575: JVMTI support when using alternative virtual thread implementation

[Alan Bateman]

On Fri, 10 Feb 2023 14:50:36 GMT, Patricio Chilano Mateo <pchilanomate at openjdk.org> wrote:

> Regarding variable _is_bound_vthread, although it's handy as a cache to avoid repeating the check, I mainly added it to avoid transitioning for GetCurrentThreadCpuTime (we are native and cannot access oops).

The timer functions need re-visiting to allow an implementation support these functions on virtual threads. Same for StopThread which needs a spec change to minimally support this function on a thread that is suspended at a breakpoint or single step event. So if we sort out these spec issues then it looks like JavaThread:: _is_bound_vthread could go away and there would be less coupling with the alt implementation.

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PR: https://git.openjdk.org/jdk/pull/12512