RFR: JDK-8202788: Explicitly reclaim cached thread-local direct buffers at thread exit

[Peter Levart]

On 06/20/2018 04:24 PM, Tony Printezis wrote:
> Hey Peter,
>
> I had written a test to test my version of the exit hooks. I can 
> easily rework it to work with yours. Interested?

Of course. Just give what you got. I can modify it as needed.

>
> To check that the native buffers are reclaimed promptly, we should be 
> able to amend the test that tests the setting of the max size for the 
> cached buffers (i.e., check that, after all the threads have exited, 
> the total native count / size is 0).

Good idea. Do you happen to know which one is it?

>
> Tony
>
>
> —————
> Tony Printezis | @TonyPrintezis | tprintezis at twitter.com 
> <mailto:tprintezis at twitter.com>
>
>
> On June 20, 2018 at 10:08:48 AM, Peter Levart (peter.levart at gmail.com 
> <mailto:peter.levart at gmail.com>) wrote:
>
>>
>> On 06/18/2018 05:41 PM, Alan Bateman wrote:
>> >
>> >
>> > On 17/06/2018 22:20, Peter Levart wrote:
>> >> Update: the discussion on concurrent-interest about possible future
>> >> addition of public ThreadLocal.getIfPresent() or
>> >> ThreadLocal.isPresent() has died out, but it nevertheless reached a
>> >> point where ThreadLocal.isPresent() was found the least problematic.
>> >> So I would like to get further with this proposal using the last
>> >> webrev.04 version of the patch that uses ThreadLocal.isPresent()
>> >> internally - still package-private at the moment.
>> >>
>> >> Here's the webrev (unchanged from the day it was published):
>> >>
>> >> 
>> http://cr.openjdk.java.net/~plevart/jdk-dev/DBBCache_Cleanup/webrev.04/ 
>> <http://cr.openjdk.java.net/%7Eplevart/jdk-dev/DBBCache_Cleanup/webrev.04/> 
>>
>> >>
>> >> Would this version be OK?
>> > I think looks quite good.
>> >
>> > One small nit is that the update to ThreadLocal.setInitialValue makes
>> > it look like all locals are registered when setting the initial value.
>> > What would you think about moving the instanceof check from
>> > TerminatingThreadLocal.register so that it's a bit more obvious.
>> >
>> > -Alan
>>
>> Like the following?
>>
>> http://cr.openjdk.java.net/~plevart/jdk-dev/DBBCache_Cleanup/webrev.05/ 
>> <http://cr.openjdk.java.net/%7Eplevart/jdk-dev/DBBCache_Cleanup/webrev.05/> 
>>
>>
>>
>> Do we need a test which proves that cached direct buffers are released
>> when thread exits or would a unit test for TerminatingThreadLocal be
>> enough? Maybe both?
>>
>> Regards, Peter
>>