[zeromq-dev] zmq context's thread priority

[Pieter Hintjens]

Feel free to send a patch for the documentation, and also a test case
if that is possible.

On Fri, Jul 10, 2015 at 9:54 AM, Leonard Michelet
<leonard.michelet at openwide.fr> wrote:
> Hello, I switch to ZeroMQ 4.1.2 because it support options to set custom priority and scheduler for context's thread, but I didn't found any documentation about these options.
> Hence, I would like to propose my help to add some text about it on pages http://api.zeromq.org/4-1:zmq-ctx-set and http://api.zeromq.org/4-2:zmq-ctx-set :
>
> ZMQ_THREAD_SCHED_POLICY: Set scheduling policy for I/O threads
> The ZMQ_THREAD_SCHED_POLICY argument sets the scheduling policy for internal context's thread pool. This option is not available on windows.
> Supported values for this option can be found in sched.h file, or at http://man7.org/linux/man-pages/man2/sched_setscheduler.2.html.
> This option only applies before creating any sockets on the context.
>
>
> ZMQ_THREAD_PRIORITY: Set scheduling priority for I/O threads
> The ZMQ_THREAD_PRIORITY argument sets scheduling priority for internal context's thread pool. This option is not available on windows.
> Supported values for this option depend on chosen scheduling policy. Details can be found in sched.h file, or at http://man7.org/linux/man-pages/man2/sched_setscheduler.2.html.
> This option only applies before creating any sockets on the context.
>
>
> I tested myself these options and it works fine and as I describe it ^^
> It's not available on windows means not available when "ZMQ_HAVE_WINDOWS" is defined.
> English is not my main language so critics are welcome.
> Nevertheless, I hope my proposal can be a first draft ^^
>
> Regards,
> Léonard Michelet.
>
>
> ----- Arnaud Kapp <kapp.arno at gmail.com> a écrit :
>> Hello,
>>
>> Note that this is my understanding of how it works, but I am not a
>> core dev so I am not sure. I may be totally wrong.
>>
>> If the IO thread does not run because of not enough CPU time I guess a
>> lot of thing can go wrong. As far as I know, messages go through the
>> IO thread for dispatching.
>> The I/O thread not running could then could prevent you from both
>> sending and receiving message.
>>
>> As for your second question, I do not know. If your application as
>> long running one, you could try to manually change the priority of the
>> threads and see if it fixes your problem.
>>
>>
>> On Mon, Jun 8, 2015 at 12:30 PM, Leonard Michelet
>> <leonard.michelet at openwide.fr> wrote:
>> > Hello, I use ZeroMQ on a Preempt_rt kernel and I have some connection problem on a virtual machine.
>> > I run automated tests on this virtual machine and its CPU is quite busy, and I noticed that my real time application, which use zmq, has 2 threads not with real time scheduler, but time shared.
>> > These thread are usually in "epoll_wait" kernel's function, and I suppose it's internal thread created by ZeroMQ (I set ZMQ_IO_THREADS to 1).
>> > I would like to know what is the purpose of these thread, to understand what symptoms I could have if these thread were never run because of not enough CPU time.
>> > Would it prevent me from receiving message? Would it prevent me to send message? Both?
>> >
>> > And my next question would be : is there a way to set priority on these thread?
>> >
>> > Thanks for reading.
>> > Léonard.
>> >
>> > P.S : the application set real time priority using pthread_setschedparam which is a per thread setting, so it doesn't change the defaullt priority of new thread, and we would like to avoid setting such a default.
>> > _______________________________________________
>> > zeromq-dev mailing list
>> > zeromq-dev at lists.zeromq.org
>> > http://lists.zeromq.org/mailman/listinfo/zeromq-dev
>>
>>
>>
>> --
>> Kapp Arnaud - Xaqq
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>
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