Promptly freeing the per-thread cached direct buffers when a thread exits

[Alan Bateman]

On 06/04/2018 15:08, Tony Printezis wrote:
> Hi Alan,
>
> Calling sun.nio directly from java.lang seemed a bit dodgy to me, 
> which is why I proposed some type of exit hook (maybe I overthought 
> this?). But that’d be OK, could make this change a lot simpler. :-) 
> And, yes, I came across the issue of not being able to query whether a 
> ThreadLocal exists on a Thread when I implemented my prototype. Which 
> is why I think introducing an exit hook on ThreadLocal, instead of 
> Thread, is probably the better approach (it will only be called if the 
> ThreadLocal exists).
>
java.lang.Thread is already tightly connected to blocking I/O operations 
(Thread::interrupt for example). In any case, the concern with exposing 
exit hooks in the API is that it means running arbitrary code when 
exiting, something that would need a lot of consideration before going 
there.

-Alan