Terminate hung calculations

[ischoegl]

For marginal cases, simulations oftentimes 'hang', i.e. they do not progress and take hours to terminate. It would be neat if there were a way to 'detect' and 'kill' a process that is hung. Probably not a priority, but it would be nice to have.

[ischoegl]

This could be done using existing callbacks, see Cantera UG discussion