RFR: 8293613: need to properly handle and hide tmp VTMS transitions [v4]

[Chris Plummer]

On Fri, 23 Sep 2022 09:30:32 GMT, Serguei Spitsyn <sspitsyn at openjdk.org> wrote:

>> src/hotspot/share/runtime/javaThread.hpp line 652:
>> 
>>> 650:   void set_is_in_VTMS_transition(bool val);
>>> 651:   void toggle_is_in_tmp_VTMS_transition()        { _is_in_tmp_VTMS_transition = !_is_in_tmp_VTMS_transition; };
>>> 652: 
>> 
>> My suggestion was to have the term "in VTMS transition" be inclusive of temp transitions. So based on your current names I would suggest:
>> 
>> - is_in_VTMS_transition -> is_in_non_tmp_VTMS_transition
>> - is_in_any_VTMS_transition -> is_in_VTMS_transition
>> 
>> But that becomes a problem for `set_is_in_VTMS_transition`, which would need to be renamed `set_is_in_non_tmp_VTMS_transition`, which I'm guessing you don't want to do. So let's instead just hope this all goes away before thinking about it any more.
>
> Thank you for sharing your suggestion.
> To be honest, I'm inclined to keep the two as simple as possible, independent end mutually exclusive.
> Temporary transitions have big difference comparing to normal transitions.
> They are allowed to be suspended and do not clash with VTMS disablers.
> Please, let me know if are okay with this.
> 
> Unfortunately, it seems, Alan got some difficulties in getting rid of temporary transitions.
> I'll double check on it just to be sure I understand it correctly.

ok

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PR: https://git.openjdk.org/jdk/pull/10321