[SR-Users] Kamailio - Missing INVITEs

[Alex Balashov]

Hi Ali,

Kamailio's SIP message processing is accomplished by worker child 
processes which are forked when Kamailio starts. The number of these 
child processes is regulated by the 'children' core parameter:

http://www.kamailio.org/wiki/cookbooks/4.3.x/core#children

Any database operation is going to block one of these worker processes 
until it returns. It's not difficult to imagine 200-300 CPS clogging up 
the workers with database queries constantly, during which time no 
incoming SIP messages will be processed, as there is no process 
available to consume them. Worse yet, the dropped requests will cause 
retransmissions, adding to the deluge of messages experienced by 
Kamailio. Anyway, if your number of 'children' is very small, you may 
consider increasing it as the most immediate solution to your problem.

Due to the high-performance interprocess communication architecture, it 
is not viable to have a large number of these child processes. There is 
some disagreement as to where the useful limit lies, but it tends to 
hover around the number of available CPU cores ('nproc'). Our experience 
with high-throughput testing suggests that having a number of children 
greater than the number of "CPUs" in /proc/cpuinfo has diminishing returns.

Ultimately, however, the architecture is what it is. Handling high-CPS 
traffic through Kamailio is an art and a science. Some suggestions:

1. Reduce the latency of your database queries still further;

2. Use a caching layer like memcached or Redis to reduce database load;

3. Take advantage of Kamailio's asynchronous processing features:

http://kamailio.org/docs/modules/4.3.x/modules/async.html

#3 involves moving call processing out of the SIP worker processes and 
into another, separate thread pool, leaving the SIP worker processes 
free to process more messages.

-- Alex

On 07/28/2015 01:40 PM, Ali Taher wrote:

> Hello,
>
> I connected Kamailio to a postgresql database (through sqlops module)
>   and fetching result from a table containing around 300K records ,
> where time processing of the single query is taking around 12 ms.
>
> I noticed that on huge load (around 200 – 300 calls per second) Kamailio
> is not processing all INVITE packets.
>
> For instance , I initialized a counter in Kamailio that increments on
> every INVITE , and on the other hand I counted the number of INVITEs
> found in Wireshark.
>
> I got a big difference  (from 30K INVITES in Kamailio , I got 15K in
> Kamailio), though no errors were raised in kamailio log.
>
> How can I proceed in order to detect the problem? L
>
> Any help would be appreciated.
>
> Regards,
>
> Ali
>
>
>
> _______________________________________________
> SIP Express Router (SER) and Kamailio (OpenSER) - sr-users mailing list
> sr-users at lists.sip-router.org
> http://lists.sip-router.org/cgi-bin/mailman/listinfo/sr-users
>


-- 
Alex Balashov | Principal | Evariste Systems LLC
303 Perimeter Center North, Suite 300
Atlanta, GA 30346
United States

Tel: +1-800-250-5920 (toll-free) / +1-678-954-0671 (direct)
Web: http://www.evaristesys.com/, http://www.csrpswitch.com/