On Thu, 30 Nov 2023 05:29:46 GMT, Chris Plummer <cjplum...@openjdk.org> wrote:
> > There is a check for virtual thread liveness which has to be good enough in
> > general:
> > ```
> > 1617 static bool should_dump_vthread(oop vt) {
> > 1618 return java_lang_VirtualThread::state(vt) !=
> > java_lang_VirtualThread::NEW
> > 1619 && java_lang_VirtualThread::state(vt) !=
> > java_lang_VirtualThread::TERMINATED;
> > 1620 }
> > . . .
> > 1919 if (java_lang_VirtualThread::is_instance(o) &&
> > ThreadDumper::should_dump_vthread(o)) {
> > 1920 _vthread_dumper->dump_vthread(o, writer());
> > 1921 }
> > ```
>
> That should in general take care of most unreachable virtual threads, but
> technically I don't think a virtual thread has to reach the TERMINATED state
> in order to become unreachable. However, it will never get scheduled.
I'm not sure I understand the scenario. The state is set to TERMINATED after
the thread completes its execution.
So a virtual thread was scheduled, mounted, did some work (as state != NEW) and
then scheduler unmounts it and decides to not schedule it again and just
"loses" it?
This does not look like a real scenario for me, but anyway I think that's fine
to report such unreachable virtual threads until GC collects the objects.
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PR Comment: https://git.openjdk.org/jdk/pull/16665#issuecomment-1834534568
