RFR: 8338383: Implement JEP 491: Synchronize Virtual Threads without Pinning [v2]

[Patricio Chilano Mateo]

On Thu, 7 Nov 2024 00:38:40 GMT, Patricio Chilano Mateo <pchilanomate at openjdk.org> wrote:

>>> So, it feels like it should not be a problem. I'm thinking if adding an assert at the VTMS transition end would help.
>>>
>> The problem here is that for monitorenter the top frame will not be a native method, so the bail out will not happen as it would when unmounting from Java.
>
>> the call to java_lang_Thread::set_is_in_VTMS_transition()is not needed in JvmtiUnmountBeginMark
>>
> Why is not needed? I guess you meant to say we should use `JvmtiVTMSTransitionDisabler::set_is_in_VTMS_transition()` which does both?

> the function is_vthread_safe_to_preempt() does not need the vthread parameter
> 
Removed.

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PR Review Comment: https://git.openjdk.org/jdk/pull/21565#discussion_r1831899049