Unknown attribute `time' when using APPSI IPOPT

[makansij]

Summary

When solving using IPOPT, it solves successfully, but when loading the results, it checks for timing data in pyros_algorithm_methods.py, and then doesn't find them so it barfs. We should handle this more gracefully.

Steps to reproduce the issue

Run the code below:

# === Required import ===
import pyomo.kernel as pmo
import numpy as np
import pyomo.environ as pyo
import pyomo.contrib.pyros as pyros

pyros_solver = pyo.SolverFactory("pyros")
m = pyo.ConcreteModel()
m.L = pyo.Var(within=pyo.Reals)

n=3
m.add_component('x1', pyo.Param(range(n), initialize=x_0_init, mutable=True))

def expression_1(m, i):
    return 0 <= m.x1[i]

fn_1 = m.x1[0]**2 + m.L
fn_2 = m.x1[0]**2 + m.L - m.x1[1]
m.obj = pyo.Objective(expr = fn_1, sense = pyo.minimize)
m.c1 = pyo.Constraint(expr = 0 <= fn_2)
m.c_rule = pyo.Constraint(range(n), rule = expression_1)
new = m.clone()
uncertain_parameters = [m.x1] # We can pass IndexedParams this way to PyROS, or as an expanded list per index
relative_deviation = 0.9
nominal_values = {0:1, 1:1, 2:0.5} 
bounds = [(nominal_values[i] - relative_deviation*nominal_values[i],
              nominal_values[i] + relative_deviation*nominal_values[i])
              for i in range(len(nominal_values))]

box_uncertainty_set = pyros.BoxSet(bounds=bounds)

solvername = 'appsi_ipopt'
ipopt_solver = pyo.SolverFactory(solvername)


local_solver = ipopt_solver
global_solver = ipopt_solver

first_stage_variables =[m.L]
second_stage_variables = []

results_1 = pyros_solver.solve(model = m,
                                   first_stage_variables = first_stage_variables,
                                   second_stage_variables = second_stage_variables,
                                   uncertain_params = uncertain_parameters,
                                   uncertainty_set = box_uncertainty_set,
                                   local_solver = local_solver,
                                   global_solver= global_solver,
                                   tee=True,
                                   options = {
                                      "objective_focus": pyros.ObjectiveType.worst_case,
                                      "solve_master_globally": True,
                                      "load_solution":False
                                    })

Error Message

Here's the stack trace:

---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
<ipython-input-7-c7c5873063e3> in <module>
     58                                         "objective_focus": pyros.ObjectiveType.worst_case,
     59                                         "solve_master_globally": True,
---> 60                                         "load_solution":False
     61                                       })
     62 else:

/usr/local/lib/python3.7/site-packages/pyomo/contrib/pyros/pyros.py in solve(self, model, first_stage_variables, second_stage_variables, uncertain_params, uncertainty_set, local_solver, global_solver, **kwds)
    431 
    432             # === Solve and load solution into model
--> 433             pyros_soln, final_iter_separation_solns = ROSolver_iterative_solve(model_data, config)
    434 
    435 

/usr/local/lib/python3.7/site-packages/pyomo/contrib/pyros/pyros_algorithm_methods.py in ROSolver_iterative_solve(model_data, config)
    170         #timing_data.total_master_solve_time += get_time_from_solver(master_soln.results)
    171 
--> 172         if k > 0:  # master feas problem not solved for iteration 0
    173             #timing_data.total_master_solve_time += get_time_from_solver(master_soln.feasibility_problem_results)
    174             pass

/usr/local/lib/python3.7/site-packages/pyomo/contrib/pyros/separation_problem_methods.py in solve_separation_problem(model_data, config)
    325                                 local_solve_time += get_time_from_solver(s.results)
    326                     else:
--> 327                         local_solve_time += get_time_from_solver(solve_data.results)
    328 
    329                 # === Terminate for timing

/usr/local/lib/python3.7/site-packages/pyomo/contrib/pyros/util.py in get_time_from_solver(results)
    181                 raise ValueError("Accessing the time for this type of solver is not supported by get_time_from_solver.")
    182         else:
--> 183             return results.solver.time
    184     else:
    185         return results.solver.time

/usr/local/lib/python3.7/site-packages/pyomo/opt/results/container.py in __getattr__(self, name)
    173         if len(self) == 0:
    174             self.add()
--> 175         return getattr(self._list[0], name)
    176 
    177     def __setattr__(self,name,val):

/usr/local/lib/python3.7/site-packages/pyomo/opt/results/container.py in __getattr__(self, name)
    282         except Exception:
    283             pass
--> 284         raise AttributeError("Unknown attribute `"+str(name)+"' for object with type "+str(type(self)))
    285 
    286     def __setattr__(self,name,val):

AttributeError: Unknown attribute `time' for object with type <class 'pyomo.opt.results.solver.SolverInformation'>