asterisk users - Sep 2013 - Asterisk high load when streaming MOH

Hi list,

I've always about 50 concurrent SIP callers listening to several MOH 
streams (fed via mpg123) on Asterisk 11.4.0, 4x 2.2 GHz and the CPU 
usage is always at about 250% causing stuttering of the streams and 
delays when using Read() and Playback() (overall everything is just 
really slow/delayed). I've seen Asterisk doing that when the MOH stream 
that was fed via mpg123 was down... then it will just go nuts. But I'm 
pretty sure that all streams are active (checked via strace). My 
question is what would be the best way to look at the internals of 
Asterisk to really find out what exactly is causing that high CPU load?

Thank you!
Markus

Sometimes I see something similar on my systems when several (3 or more) MOH
streams are fed by
mpg123. Suddenly some or all streams are stuttering, but the CPU load
doesn't seem to go up
significantly.

Have you looked at what is happening with the receive queue of mpg123 (pgrep
mpg123 and netstat
-t -p)?

I have written a small daemon for myself that watches the receiving tcp streams
and if nothing
seems to be happening, simply touches musiconhold.conf and issues an
"asterisk -rx \"moh
reload\"". Not nice, but it works, eventually. When I listen to the
same music streams I find
that they are not as stable as one would wish, at least at a time scale of
several hours.

When using several moh file classes, I have never hat audio problems.

jg