Retrieve Solver Log Files in AIMMS Developer

Solvers can share information about the solution process up to a very detailed level. To avoid overhead in generating information that is not inspected anyway, the AIMMS IDE defaults to not sharing any information.

Get started with log files

The first option is to set the option solver_listing_messages to all. By just setting this option, a solver will generate a small log file with the name <solver name>.sta in the folder log. The first solve of an AIMMS session will create the file, subsequent solves will append to the file. To generate a log file, we used the Flow Shop example with 14 jobs and 20 machines and solved it using CPLEX 12.8 on my desktop.

1
2Solve problem 'FlowShopModel' with 554 rows, 476 columns (196 binaries, 0 generals), and 8808 nonzeros.
3
4MIP - Integer optimal solution:  Objective = 3.8900000000e+002
5Solution time = 71.72 sec.  Iterations = 6163443  Nodes = 101990
6

Additional information and example

For a MIP problem, a typical first setting to add is the option MIP display to Display each nth node. Thus I obtained a 95 line log file log\cplex 12.8.sta. For the sake of brevity, I only show the first and last five lines here.

1Solve problem 'FlowShopModel' with 554 rows, 476 columns (196 binaries, 0 generals), and 8808 nonzeros.
2Tried aggregator 3 times.
3MIP Presolve eliminated 0 rows and 1 columns.
4MIP Presolve modified 7561 coefficients.
5Aggregator did 25 substitutions.

Last five lines:

90                          ------------
91Total (root+branch&cut) =   72.72 sec. (45534.38 ticks)
92
93MIP - Integer optimal solution:  Objective = 3.8900000000e+002
94Solution time = 72.72 sec.  Iterations = 6163443  Nodes = 101990

Overview of options to try out first for logging

This section presents, based on problem type and solver, a list of first options to be set for more information. This is not a list of options to improve performance, but a first step to obtain more information about the solution process so analysis of the solution process can be started.

LP Problems solved using Barrier

Solver

Option

Value

CPLEX

Barrier display

Normal

GUROBI

Output file

yes

CBC

Status File

File

LP Problems solved using SIMPLEX

Solver

Option

Value

CPLEX

Simplex display

At refactorizations

GUROBI

Output file

yes

CBC

Status File

File

MIP Problems

Solver

Option

Value

CPLEX

MIP display

Display each nth node

ODH-CPLEX

Status display

Yes

MIP display

Display each nth node

GUROBI

Output file

yes

CBC

Status File

File

Note

For ODH-CPLEX, setting the option MIP display requires setting the option Status display to Yes.

NLP Problems

Solver

Option

Value

BARON

Keep results file

On

CONOPT

Status file display

Iteration log

IPOPT

Status file

Yes

KNITRO

Status file display

Summary

SNOPT

Print output file

On

Further reading

The interpretation of log files is discussed in:

  • LP at https://pdfs.semanticscholar.org/b01f/ad44c20c372fdda95cbfb980c0d37302de07.pdf

  • MIP at https://pubsonline.informs.org/doi/10.1287/educ.2014.0130