[VoxBo] Matlab licenses and timeouts

[Daniel Y Kimberg]

Thad Polk wrote:
> We're having trouble using a central Matlab license server with
> VoxBo. The problem is that everytime VoxBo runs a Matlab job it
> opens up 4 TCP connections and those connections stick around long
> after the Matlab job has completed. Once a few dozen Matlab jobs
> have been scheduled, we therefore have 100s of TCP connections to
> the server. The server gets unhappy and crashes. This affects
> everyone in the university who accesses this central server, making
> us rather unpopular!

Hi Thad.  I thought we had gotten to the root of this before, or was
that with IDL?  Let me throw out a few thoughts.  First, MATLAB-based
jobs are run by starting MATLAB, issuing a few commands through the
standard input, and exiting.  So if VoxBo opens up 4 TCP connections
when running a single SPM (or whatever) job, then the same is true for
interactive terminal sessions.

There is one difference that might be relevant, which is that it's
possible the VoxBo server could exit before the MATLAB session is
terminated (e.g., if the exit command isn't issued).  I don't think
this is possible in the code right now, but it's a logical possibility
if the server crashes.  It's also possible things get a little crazy
if there aren't enough licenses, but I imagine that's also an unusual
situation.

I assume the crash you're talking about is just the license server
process suddenly ceasing to exist.  As an aside, this would be a
severe bug in the license server, and it would be worth reporting to
the vendor.  I'm a little surprised that this would happen with only a
few dozen instances.  But since it seems like the license server can't
handle the rate at which you're spawning MATLAB jobs, you may have to
rate-restrict them somehow.  You could easily set it up in your VoxBo
config files so that only n of your hosts "provide" matlab, and so
that they only provide a single instance.  (I'm away from the office
right now, let me know if you need the syntax for that.)

You might also consider configuration changes to the license server,
which ought to run more stably.

dan