Solver (cplex) returned non-zero return code (-1)

[Pancho]

I'm getting the following error after trying to solve a model using pyomo:

ERROR: Solver (cplex) returned non-zero return code (-1)
ERROR: See the solver log above for diagnostic information.
ERROR: Unexpected exception while running model Subproblem.py:
    Solver (cplex) did not exit normally

However, I can solve the model without any problems from the cplex command line if I only use pyomo to build the lp file.

I couldn't find the meaning the return code online.

Pancho

[Watson, Jean-paul]

Assuming you are scripting, can you solve with "tee=True" added as a keyword argument to the solve() command (and post the output)? 

I don't know what precisely is going on, but I do know that return codes are sketchy for both CPLEX and Python. 

jpw

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[Pancho]

I got that output from the pyomo command line (i.e. pyomo model.py data.dat --stream-solver --report-timing)

Pancho

[Gabriel Hackebeil]

Is what you posted the full output? We're hoping to see what the CPLEX output tells us about the solution status.

Gabe

[Watson, Jean-paul]

This almost seems like the subprocess launch failed. Is this under Windows?

jpw

[Pancho]

No, it is under Linux.

[  187.20] Applying solver
[  215.76] Processing results
    Number of solutions: 0
    Solver results file: results.json
Problem loading solver results

ERROR: Unexpected exception while running model Subproblem.py

    Cannot load a SolverResults object with bad status: error

{
    "Problem": [
        {
            "Lower bound": -Infinity,
            "Number of constraints": 0,
            "Number of nonzeros": null,
            "Number of objectives": 1,
            "Number of variables": null,
            "Sense": "unknown",
            "Upper bound": Infinity
        }
    ],
    "Solver": [
        {
            "Error rc": -1,
            "Status": "error",
            "Termination condition": "unknown"
        }
    ]

[Siirola, John D]

FWIW, what you just pasted does not match your original snippet: you original snipped indicated that there was a CPLEX problem and that the CPLEX subprocess returned a non-zero return code.  What you just posted appears to have no CPLEX problems (and also appears to have not been run with the --stream-solver option).

 

One additional thought: have you tried running CPLEX through the direct python bindings (that is, “--solver cplex --solver-io python”)?

[Pancho]

Now the model works well if I solve it from the pyomo command line using the VOTD, but it returns the following when executed from a script (Benders decomposition):

.
.
.
 161   8.5343932e+02   8.5343930e+02  9.25e-03  8.79e-07  2.75e-09  9.33e+10
 162   8.5343932e+02   8.5343930e+02  1.37e-02  9.74e-07  2.70e-09  9.53e+10
 163   8.5343932e+02   8.5343931e+02  1.35e-02  7.97e-07  2.18e-09  1.20e+11
 164   8.5343932e+02   8.5343931e+02  1.33e-02  1.01e-06  2.16e-09  1.21e+11

Total time on 4 threads =   24.43 sec.

Barrier - Optimal:  Objective =  8.5343931712e+02
Solution time =   24.43 sec.  Iterations = 164
Deterministic time = 17777.64 ticks  (727.67 ticks/sec)

CPLEX> Solution written to file '/tmp/tmpUxzn5E.cplex.sol'.
CPLEX> Killed

It seems that cplex is solving it, but for some reason the process is being killed at the end.

Pancho

[Watson, Jean-paul]

Grumble. Can you send the script off-line? I'm doing the exact same thing in various places, w/o issue.

jpw

From: Pancho <elpanc...@gmail.com>
Reply-To: "coopr...@googlegroups.com" <coopr...@googlegroups.com>
Date: Tuesday, April 16, 2013 1:08 PM
To: "coopr...@googlegroups.com" <coopr...@googlegroups.com>

[Pancho]

sent