Consider Adding Thread Affinity

[Suminda Sirinath Salpitikorala Dharmasena]

Hello,

Thanks for the pointer.

I am aware of a few libraries tackling the Thread Affinity issue, but I was
not aware of this specific solution. I will check it out.

I was hoping that this might eventually get tacked at the core library
level than having to use a library.

Thanks again for the pointer.

Suminda

On Tue, 1 Dec 2020 at 11:40, Enrico Olivelli <eolivelli at gmail.com> wrote:

> Suminda,
> In Apache Bookkeeper project we have this module, available on Maven
> Central
> It allows to control thread affinity.
>
> https://github.com/apache/bookkeeper/tree/master/cpu-affinity
>
>
> I hope that helps
> Enrico
>
>
>
>
> Il Mar 1 Dic 2020, 00:15 David Holmes <david.holmes at oracle.com> ha
> scritto:
>
>> On 1/12/2020 2:53 am, Suminda Sirinath Salpitikorala Dharmasena wrote:
>> > This mainly aims to prevent cache misses as:
>> > - previously cached values of the thread may be in the cache
>> > - threads which share data can be targeted at a given core for better
>> data
>> > locality
>> > - ensure threads are planned based on locks are common/shared
>> > resource usage which is known to the programmer than OS
>> >
>> > I believe this is an important feature to consider for performance.
>>
>> Are you talking about virtual threads or regular (carrier) threads?
>>
>> General thread affinity has been raised in the past but it is a highly
>> sensitive operation in relation to performance and extremely easy to
>> misuse (hurting not only the performance of your own application but
>> potentially the whole machine). Further to support thread affinity you
>> also need a way to expose detailed CPU topology information (sockets,
>> processors, cores) that does not presently exist in Java and which was
>> considered too machine/hardware specific to be considered a good
>> candidate for a portable Java API. With virtualized environments of
>> various forms, thread affinity is even harder to use.
>>
>> Also note that the system/OS scheduler will itself try to address
>> low-level cache affinity when making scheduling decisions.
>>
>> Cheers,
>> David
>> -----
>>
>> > Suminda
>> >
>> >
>> > On Mon, 30 Nov 2020 at 21:22, Ron Pressler <ron.pressler at oracle.com>
>> wrote:
>> >
>> >> Hi.
>> >>
>> >> We have no concrete plans for doing so, but can you, perhaps, explain
>> the
>> >> use-case and why it’s important?
>> >>
>> >> — Ron
>> >>
>> >>
>> >> On 27 November 2020 at 14:17:07, Suminda Sirinath Salpitikorala
>> Dharmasena
>> >> (sirinath1978m at gmail.com) wrote:
>> >>
>> >> Hello,
>> >>
>> >> Is it possible to consider adding thread affinity to the Thread API?
>> >>
>> >> Suminda
>> >>
>> >>
>>
>