[Freeswitch-users] Which Lua script am I?

Mike van Lammeren mike at van.lammeren.net
Fri Mar 5 11:04:54 PST 2010


I am working on a high-availability system and need a Lua script that can
run in the background and loop forever, periodically waking up to accomplish
some tasks. I would like to be able to handle at least 10 concurrent tasks.

My first idea was to have a simple background script that would call another
script, let's call it the 'task' script, every 5 seconds or so. This would
spread the work around, and if any task script quit with an error, the
background script would remain running, and would continue to launch new
task scripts.

However, I can see no way for the background script to launch other Lua
scripts. Am I missing something? I need something like session:execute(),
but unfortunately this background script has no session, and I'm not sure if
session:execute() can even make a call like the "luarun" console command.

So, my next ideas was to have 10 copies of the background script. Each
script would loop forever. Upon launch, each script would perform a single
task, then sleep for 60 seconds. This allows handling of 10 concurrent

However, there are some problems with running 10 copies of the same script,
which I believe can be solved if each script could be given a unique
identifier. One problem is that I would like the scripts to actually sleep
for a variable amount of time, say between 55 and 65 seconds, so that the
workload would spread around. Another, similar problem, is that each script
needs to 'claim' a number of database records from a table that is queuing
up work for the scripts. Once again, if each script had a unique identifier,
then I could use an update query to effectively 'set and test' a record that
would be tied to that script instance.

I could use a random number to identify each script, but since math.random
is seeded with a timestamp that only resolves to seconds, then all 10
scripts will be given the same sequence of random numbers, and all 10 will
run in lock-step with each other. So, random numbers are out. (If I had a
unique ID to seed the random number generator, then I could just use that
unique ID and wouldn't need random numbers.)

Is there a way of uniquely identifying 10 Lua scripts that FreeSWITCH
launches at startup?

Or is there a better way of handling this situation altogether? I'm open to
any suggestions that people would care to make!

(I would entertain the idea of a single script that would start with
FreeSWITCH, then launch 10 other scripts, giving each a unique identifier,
but that brings me back to the original problem of not knowing how to launch
other Lua scripts under FreeSWITCH.)

Mike van Lammeren
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