Floating licenses have a use limit, which is enforced by monitoring when tokens are issued/released. If all tokens are in use, any application attempting to use Gurobi to solve optimization problems will get the error “Request denied: use limit (N) exceeded”. On the other hand, Compute Server and Instant Cloud are based on the client-server paradigm. As such, optimization jobs are issued to the optimization server by clients. Users may observe that a job is still running, even after the optimization task has finished.
One reason for the situations described above is that the user forgot to dispose of all models and environments at the end of the session. The steps to do so vary by programming language:
- C: Call GRBfreemodel() for each model, then call GRBfreeenv() for the Gurobi environment.
- C++: If you use pointers to GRBModel and GRBEnv objects, delete all GRBModel objects, then delete the GRBEnv object.
- .Java: Call GRBModel.dispose() on all GRBModel objects, then call GRBEnv.dispose() on the GRBEnv object.
- .NET: Call GRBModel.Dispose() on all GRBModel objects, then call GRBEnv.Dispose() on the GRBEnv object.
If you neglect to do this cleanup, the license may be temporarily unavailable for other applications.