[erlang-questions] inaccurate interval timer

Mark Geib <>
Thu Nov 15 05:11:21 CET 2012


I was just pointing out that the log message are emitted every 25ms as indicated by the timestamp on the log messages, but the network message are being sent in a slightly shorter period.

Mark.

On Nov 14, 2012, at 8:59 PM, Yogish Baliga wrote:

> Log messages are emitted from a different Erlang process than the process actually sending UDP message. Details are in message passing and erlang process scheduler 
> 
> -- Baliga 
> 
> 
> 
> On Nov 14, 2012, at 19:12, Mark Geib <> wrote:
> 
>> I am using timer:send_interval(..) to generate recurring messages that drive the sending of UDP packets at a given rate. However, using a network analyzer I am observing that the network datagrams are being sent at a rate greater than the intended rate. Log messages with timestamps indicate the erlang code is sending the datagrams at the proper time. So the question is whether the erlang VM could possibly have a clock that is "tic-ing" at a incorrect frequency, or this an issue with the underlying OS, linux in this case. The interval of the timer is set to 25ms, I am observing times of 23.7-24.5ms. Also, this is only happening on a single machine, testing on four other machines confirms proper rates are being generated.
>> 
>> I am running ubuntu 12.04 fully updated with erlang R14B04.
>> 
>> Thanks for any help or suggestions.
>> 
>> Mark.
>> 
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