RFR: 8298853: JvmtiVTMSTransitionDisabler should support disabling one virtual thread transitions [v6]

[Serguei Spitsyn]

On Sat, 11 Feb 2023 01:43:07 GMT, Serguei Spitsyn <sspitsyn at openjdk.org> wrote:

>> Now the `JvmtiVTMSTransitionDisabler` mechanism supports disabling VTMS transitions for all virtual threads only. It should also support disabling transitions for any specific virtual thread as well. This will improve scalability of the JVMTI functions operating on target virtual threads as the functions can be executed concurrently without blocking each other execution when target virtual threads are different.
>> New constructor `JvmtiVTMSTransitionDisabler(jthread vthread)` is added which has jthread parameter of the target virtual thread.
>> 
>> Testing:
>>   mach5 jobs are TBD (preliminary testing was completed):
>>    - all JVMTI, JDWP, JDI and JDB tests have to be run
>>    - Kitchensink
>>    - tier5
>
> Serguei Spitsyn has updated the pull request incrementally with one additional commit since the last revision:
> 
>   minor comments are resolved

Thank you a lot for reviewing, Leonid!
Will update the copyrights.

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PR: https://git.openjdk.org/jdk/pull/11690