We have implemented call center using a freeswitch as switch for handling calls. It is basically the logic where you have an agents within the queue waiting for an contacts to come in, or contact within the queue waiting if there is no any agents available.

For this kind of implementation we used pure lua and hash tables (and not mod_fifo) in order to have a better flexibility and possibility to manage different contact/agent states.

Everything was working fine on our old servers, now we are migrating to the cloud and we are using aws for that purpose, of course trying to cut some costs.

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After initial setup of our solution we found out that there is a memory leak causing for freeswitch to consume 3 - 10 MB per minute during production hours.  (we did not notice anything on old servers because we had like 24 cores and 94GB of ram on those).

This is not too much of course but the bottom point is that increase is linear and its constantly raising consuming more and more of RAM.

In order to isolate an issue and to conclude that we don't have an issue within our solution I installed 1.6.7 version of freeswitch and setup really simple call center with mod_fifo without anything else (totally independent from call center we are working on)

For the reference:

Aws: m4.large

         vCPU: 2

         RAM: 8GB

         Throughput (Mbps): 450         

Freeswitch version: 1.6.7
OS: Debian GNU/Linux 8 (jessie)

Number of agents: 30

Number of calls per agent: 1

Total numbers of channels at time: 60

Agents simulated with: pjsip(http://www.pjsip.org/)

Contact simulated with: sipp(http://sipp.sourceforge.net/) 

Configuration: I used configuration which came with installation of freeswitch. The only things i changed is:

     - default password

     - internal rtp timeout

     - rtpip and sip ip

Test scenario:
1. Start the freeswitch.
2. Autoload lua script is going to ring all of the internal (agents) and push them to the extension where we had mod_fifo 
3. After some time, same autoload script is going to start calling contacts each 800 miliseconds and push them to the extension where we have mod_fifo.

4. mod_fifo will do the rest, bridge agent with the contact and handling the queue properly.

As a result we will have 30 agents constantly "talking", and when ever call is dropped we will have agent connected with another. Parameters for the test match that scenario, and we dont have more then 60 - 65 channels open at the time (never).

Dialplan for handling mod_fifo