[zeromq-dev] Delayed message reception problem.

[Divya Mohan]

Hi Pieter,

Please find attached the test code.

*Test Description: *
send_process: - Gets the time before sending a message and sends it as part
of the message.
                      -  Message send continuously with a delay of 1 ms.
                      -  Uses ZMQ_PUB socket and IPC protocol.

recv_process:  -  After receiving the message, calculates the time
difference between send and receive times.
                      -  If the difference is greater than 10 ms, prints
the message number and delay info(In the actual test code I am sending to
logging application using ZMQ_PUB and TCP protocol)
                      - Uses ZMQ_SUB and IPC protocol.

*Test ran for more than 48hrs.*
*NOTE:  Message delay will be seen only after running the test for a couple
of hours. (in my case after 10 hrs)*

*Test Configuration:*
- Freescale quad core ARM processor.
- 1 GHz processor
- OS : Ubuntu 10.04

Thanks,
Divya


On Mon, Apr 15, 2013 at 12:52 PM, Pieter Hintjens <ph at imatix.com> wrote:

> Hi Asif,
>
> I'm hoping Divya will provide us with reusable tests that show the problem.
>
> -Pieter
>
>
>
>
>
> On Mon, Apr 15, 2013 at 7:50 AM, asif saeed <asif.lse2 at gmail.com> wrote:
> > Excellent, Divya. Very good analysis.
> >
> > @Pieter,
> >
> > I am also going to use ZeroMQ in an Ubuntu environment and Divya's
> analysis
> > is really worrying me. Does ZeroMQ have benchmarks on non real-time
> systems?
> > What kind of performance tests are there to test the performance?
> >
> > Sincerely,
> >
> > -Asif
> >
> >
> > On Fri, Apr 12, 2013 at 10:29 PM, Divya Mohan <divya.mohan310 at gmail.com>
> > wrote:
> >>
> >> Hi Pieter,
> >>
> >> I tried the same performance tests with POSIX message queues and there
> was
> >> no delay in receiving the messages. The same test with ZeroMQ showed
> delays
> >> of upto 470msec. Doesn't this mean that we can rule out the possibility
> of
> >> another process taking up CPU time randomly (as you had suggested
> earlier)?
> >>
> >> Are there any sleep/wait (for semaphores) in the zeromq code that could
> >> send my process to suspeneded/sleep state. I am not able to figure out
> why
> >> this delay is seen when using ZeroMq and not with message queues.
> >>
> >>
> >>
> >> Thanks,
> >>
> >> Divya
> >>
> >>
> >>
> >>
> >>
> >> On Thu, Mar 28, 2013 at 3:54 PM, Pieter Hintjens <ph at imatix.com> wrote:
> >>>
> >>> On Wed, Mar 27, 2013 at 4:51 PM, Divya Mohan <divya.mohan310 at gmail.com
> >
> >>> wrote:
> >>>
> >>> > Current and default scheduling policy is SCHED_OTHER. I had given
> >>> > highest
> >>> > priority to my receive process thinking delay due to scheduling will
> be
> >>> > taken care off but even then the messages are delayed.
> >>> >
> >>> > Also I am not using any sleep in  my receive process. Only send
> process
> >>> > has
> >>> > a sleep of 1 msec.
> >>>
> >>> In general changing thread priorities is a bad idea.
> >>>
> >>> Perhaps you have another process taking CPU time at random occasions,
> >>> causing the sender I/O thread to be swapped out.
> >>>
> >>> If you want guarantees that there are no spikes you'll have to use a
> >>> real time kernel. It will increase average latency but remove the
> >>> spikes.
> >>>
> >>> -Pieter
> >>> _______________________________________________
> >>> zeromq-dev mailing list
> >>> zeromq-dev at lists.zeromq.org
> >>> http://lists.zeromq.org/mailman/listinfo/zeromq-dev
> >>
> >>
> >>
> >> _______________________________________________
> >> zeromq-dev mailing list
> >> zeromq-dev at lists.zeromq.org
> >> http://lists.zeromq.org/mailman/listinfo/zeromq-dev
> >>
> >
> >
> > _______________________________________________
> > zeromq-dev mailing list
> > zeromq-dev at lists.zeromq.org
> > http://lists.zeromq.org/mailman/listinfo/zeromq-dev
> >
> _______________________________________________
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>
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