Originally posted by: SystemAdmin

[sdwow said:]

How can I save the engine log generated by OPL. I run the opl model via c++/java.  Is there a function that returns this log?

Thanks,
SD
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#OPLusingCPLEXOptimizer

Originally posted by: SystemAdmin

[Didier Vidal said:]

Depending on the optimization engine you use, you can use IloCplex.setOut or IloCP.setOut to redirect the engine log to the java OutputStream you want. If you want to redirect to a file, you can create a FileOutputStream (http://java.sun.com/j2se/1.4.2/docs/api/java/io/FileOutputStream.html)

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#OPLusingCPLEXOptimizer

Originally posted by: SystemAdmin

[sdwow said:]

Thank you very much. I created a new FileOutputStream and used the function getCplex().setOut() as shown below.

String name= "NEW_log.txt";
FileOutputStream log = new FileOutputStream (new File(name));
oplModel.getCplex().setOut(log);

However, now I get multiple files. How can I dump it all into a single file?

I appreciate your help and pointing me to the right direction.
Thanks,
SD
#DecisionOptimization
#OPLusingCPLEXOptimizer

Originally posted by: SystemAdmin

[Didier Vidal said:]

Why don't you use the same file stream for all your CPLEX runs ?
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#OPLusingCPLEXOptimizer

Originally posted by: SystemAdmin

[sdwow said:]

Yes, I resolved that issue and I do get all the log into one file "NEW_log.txt". however, The file looks like this:

Tried aggregator 1 time.
MIQP Presolve eliminated 846 rows and 750 columns.
Aggregator did 157 substitutions.
Reduced MIQP has 317 rows, 319 columns, and 1174 nonzeros.
Presolve time =    0.02 sec.
MIP emphasis: balance optimality and feasibility.
MIP search method: dynamic search.
Parallel mode: none, using 1 thread.
Root relaxation solution time =    0.00 sec.

      Nodes                                        Cuts/
  Node  Left    Objective  IInf  Best Integer    Best Node    ItCnt    Gap

    400  179        4.3728    11        5.1620        3.7651    2393  27.06%
    500  217        4.2886    17        5.1620        3.8711    3014  25.01%
    600  254        cutoff              5.1620        3.9650    3599  23.19%
    700  285        4.1001    11        5.1620        4.0347    4439  21.84%
    800  301        4.8879    16        5.1620        4.1647    5422  19.32%
    900  310        4.6655    11        5.1620        4.2546    6140  17.58%
  1000  315        4.8482    23        5.1620        4.3610    7079  15.52%
Elapsed time =  0.47 sec. (tree size =  0.10 MB, solutions = 0)
  1100  299        4.7757    11        5.1620        4.4764    7994  13.28%
  1200  268        4.7769    11        5.1620        4.6220    8793  10.46%
  1300  203        cutoff              5.1620        4.7591    9640    7.81%

--------------------------------------------------------------------------

However, I do not get the rest of the output which is generally generated by CPLEX and shown by OPL.
Example:
Mixed integer rounding cuts applied:  2
Gomory fractional cuts applied:  3

OR

Root node processing (before b&c):
  Real time            =    0.52
Parallel b&c, 2 threads:
  Real time            =    2.81
  Sync time (average)  =    1.41
  Wait time (average)  =    1.41
                          -------
Total (root+branch&cut) =    3.33 sec.

Let me know how I can view or write this into the log file.

SD
#DecisionOptimization
#OPLusingCPLEXOptimizer

Originally posted by: SystemAdmin

[Didier Vidal said:]

That's surprising.

The first thing I would try is to 'flush' the stream after each CPLEX run, by calling


elog.flush();


Didier.
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#OPLusingCPLEXOptimizer

Originally posted by: SystemAdmin

[sdwow said:]

Thank you Didier,

I tried using the flush() stmt. For a very simple problem here is the engine log file that gets saved:

Tried aggregator 1 time.
MIP Presolve eliminated 90 rows and 6 columns.
Aggregator did 157 substitutions.
Reduced MIP has 81 rows, 158 columns, and 317 nonzeros.
Presolve time =    0.00 sec.
MIP emphasis: balance optimality and feasibility.
MIP search method: dynamic search.
Parallel mode: none, using 1 thread.
Root relaxation solution time =  -0.00 sec.

        Nodes                                        Cuts/
  Node  Left    Objective  IInf  Best Integer    Best Node    ItCnt    Gap

*    0    0      integral    0        0.0000        0.0000      20    0.00%


As you can see the complete pre-processing is seen and the solution was almost instantaneous. But I still do not get anything after the solution as mentioned in my previous post.

Thanks a lot. Your suggestions have helped me a lot.
SD


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#OPLusingCPLEXOptimizer

Originally posted by: SystemAdmin

[Didier Vidal said:]

I'm afraid I'm out of ideas...

Just a last thing, that I couldn't test (I'm working on a mono-cpu computer today)

The log part you displayed seems to be specific to parallel cplex.

Have you set the CPLEX parameters to request a multi-thread optimization ? For instance :

cplex.setParam(IloCplex.IntParam.Threads, 2);


Didier.
#DecisionOptimization
#OPLusingCPLEXOptimizer

Originally posted by: SystemAdmin

[sdwow said:]

I changed the MIPDisplay settings to 4 and that helped.
      cplex.setParam(IloCplex.IntParam.MIPDisplay,4);

Thank you very much for your help. I am a beginner at OPL and learning my way around :)
SD
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#OPLusingCPLEXOptimizer