GurobiDirect does not save logfiles when requested

[bknueven]

Summary

The logfile keyword argument to solve does not work correctly for GurobiDirect.

Steps to reproduce the issue

from pyomo.environ import *
m = ConcreteModel()
m.x = Var()
m.c = Constraint(expr=(0.0, m.x, 1.0))
m.o = Objective(expr=m.x)

s = SolverFactory("gurobi_direct")
s.solve(m, logfile="gurobilog.out")

gurobilog.out is nowhere to be found. This seems to work correctly for other solvers, e.g., xpress, ipopt, cbc,..

Information on your system

Pyomo version: 32591c1
Python version: 3.12.9
Operating system: macOS
How Pyomo was installed (PyPI, conda, source): source
Solver (if applicable): Gurobi

[quantresearch1]

Hi,

Looking from the code, this is not a bug. You need s.solve(m, logfile="gurobilog.out", keepfiles=True, tee=True).
See pyomo\solvers\plugins\solvers\gurobi_direct.py

    def _apply_solver(self):
        StaleFlagManager.mark_all_as_stale()

        if self._tee:
            self._solver_model.setParam('OutputFlag', 1)
        else:
            self._solver_model.setParam('OutputFlag', 0)

        if self._keepfiles:
            # Only save log file when the user wants to keep it.
            self._solver_model.setParam('LogFile', self._log_file)
            print("Solver log file: " + self._log_file)

If you confirm this works, could you please this issue ? Many thanks !

[rschwarz]

I can confirm that setting tee=True will add the Gurobi output to the log files, but also to the console, which is not always wanted.

For our application, I'd like have the solver output only in the log file.

Thus, I think the implementation in GurobiDirect._apply_solver is slightly incorrect, in that the Gurobi parameter LogToConsole should be used instead of OutputFlag.

I tested this locally and it makes my preferred configuration work.

I will prepare a pull request...