[Cbc] Restricting computation time for infeasible problems

[Christopher Gross]

Hi,

I am using CMPL with CBC as a backend in a software that is used without me
being present. The users are able to enter data into the software which will
then generate a data file and solve the model I created. Currently, the
software is in the testing stage so users expect timely feedback. I have
therefore limited the solution time to 120 seconds which gives quite good
solutions so far.

Sometimes, users enter data that leads to infeasibilities in the model.
Often, this results in a quick failure (within a few seconds) with an error
message. Sometimes, however, it might take very long for CBC to fail. In the
most recent instance of this problem it took the solver more than 20 minutes
of processing at which point the users called me and asked me to kill the
process so they could try again with different data.

Obviously, it is undesirable to have CBC processing for such a long time.
Ideally, I would like to always terminate after 120 seconds and then give
the user the intermediate result, whether a solution has been found or not.

Why is CBC sometimes taking so long when presented with an infeasible
problem? And what can I do to limit this time?

Thanks and best regards,

Christopher
--
Christopher Gross, M.Sc.

Lehrstuhl für Health Care Operations/Health Information Management

Universitäres Zentrum für Gesundheitswissenschaften am Klinikum Augsburg -
UNIKA-T, Neusässer Straße 47, 86156 Augsburg

Wirtschaftswissenschaftliche Fakultät, Universität Augsburg,
Universitätsstraße 16, 86159 Augsburg

Tel.: +49 821 598-6454
E-Mail: christopher.gross at unikat.uni-augsburg.de
Web: http://www.wiwi.uni-augsburg.de/bwl/brunner/