[Freeswitch-users] high load with ~200 fax calls despite low CPU utilization and low IO wait

[Adam Johnston]

Hi all,

My FreeSWITCH setup works as follow: I have a service that launches and
monitors faxes (via event sockets) on one of a few FreeSWITCH instances.
These FreeSWITCH instances are running on dual-core, 2ghz CentOS 5.8 and
CentOS 6.0 VMs. The issue is that once I get to ~200 simultaneous faxes on
any one FreeSWITCH VM the load average shoots up (typically ~30, although
I've seen it get much higher) and the VM becomes sluggish and occasionally
unusable.

top and sar output confirms that CPU utilization is pretty low, as are IO
wait and RAM usage.

I'm using a git head from 2012-02-06, although I see the same problem if
update to a more current head. On the most recent head I tried (2012-08-06)
the issue is worse, and crashes with a backtrace similar to this Jira,
http://jira.freeswitch.org/browse/FS-2893 despite my compiling Lua and
including the FreeSWITCH bindings.

These issues occur on both the CentOS 5.8 and 6.0 VMs. I'm in the process
of loading 5.8 onto a physical machine and testing there. It's also worth
nothing that this load issue does not occur when I launch faxes from a
script on one of the VMs.

Has anyone else seen similar high load issues before?

Many thanks,
Adam Johnston
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