On Wed, 15 May 2024 06:00:46 GMT, Serguei Spitsyn <sspit...@openjdk.org> wrote:
>> I'm not sure this answered Chris' query properly. Or I'm reading Chris' >> query wrong. >> >> Perhaps this is not what Chris had in mind, but I'm wondering what happens >> in some >> Thread-A when it is checked and passed by but then Thread-A sets the flag in >> itself >> after the for-loop has passed it by. Does that Thread-A flag value get lost? > >> Perhaps this is not what Chris had in mind, but I'm wondering what happens >> in some >> Thread-A when it is checked and passed by but then Thread-A sets the flag in >> itself >> after the for-loop has passed it by. Does that Thread-A flag value get lost? > > Thank you for the question. > The Thread-A sets the flag optimistically and then re-checks if > `sync_protocol_enabled()` and any disabler exists. It can be global disbaler > (`_VTMS_transition_disable_for_all_count > 0`) or disabler of `Thread-A` only > (`java_lang_Thread::VTMS_transition_disable_count(vth()) > 0`). If any > disabler exists then `Thread-A` clears the optimistic settings and goes with > the pessimistic approach under protection of `JvmtiVTMSTransition_lock`. > > Please, let me know if you still have questions. This algorithm sounds correct. Thanks for closing the loop on my belated comment. ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/18937#discussion_r1603957324
