Originally posted by: windyyy

Hi All,

I am using OPL Java API for solving cutting stock problem using column generation, similar as the example of "C:\Program Files\IBM\ILOG\CPLEX_Studio1262\cplex\examples\src\java\CutStock.java". The data set is read from an excel file. The outline of the program is as follows:

 

IloCplex MasterPro=new IloCplex();

IloObjective CostCoeffi=MasterPro.addMinimize();   

IloRange[] Constraints=new IloRange[NumberXXX]; 

 

After initialization the master problem by adding some columns, a subproblem is solved to generate new columns and then be added into the 'VariablePool', until no better columns can be found:

 

VariablePool.add(MasterPro.numVar(NewColumn,0.0,Double.MAX_VALUE));

 

static class IloNumVarArray {

        int _num           = 0;

        IloNumVar[] _array = new IloNumVar[24];

        void add(IloNumVar ivar) {

            if ( _num >= _array.length ) {

            IloNumVar[] array = new IloNumVar[2 * _array.length];

            System.arraycopy(_array, 0, array, 0, _num);

            _array = array;

            }

            _array[_num++] = ivar;

        }

        IloNumVar getElement(int i) { return _array[i]; }

        int       getSize()         { return _num; }

    }   

 

When the problem scale is small, the whole program runs well. However, internal problems as follows show up when the problem size becomes larger:

 

Exception in thread "main" java.lang.RuntimeException: internal error (Please notify IBM)

        at ilog.concert.cppimpl.concert_wrapJNI.new_IloNumVar__SWIG_8(Native Method)

        at ilog.concert.cppimpl.IloNumVar.<init>(IloNumVar.java:81)

        at ilog.cplex.IloCplex.numVar(IloCplex.java:491)

        at ilog.cplex.IloCplex.numVar(IloCplex.java:511)

        at ilog.cplex.IloCplex.numVar(IloCplex.java:519)

        at HelenCplexbefore.RenshuMiniInitial.ColumnGeneration(RenshuMiniInitial.java:1870)

        at HelenCplexbefore.RenshuMiniInitial.main(RenshuMiniInitial.java:4663)

 

The 'RenshuMiniInitial.java:1870' corresponds to the line of adding new columns of 'VariablePool.add(MasterPro.numVar(NewColumn,0.0,Double.MAX_VALUE));' And also I have the knowledge that the problem may occur during adding new columns from 'at ilog.concert.cppimpl.concert_wrapJNI.new_IloNumVar__SWIG_8(Native Method)'. But I can't find any related information about the ".new_IloNumVar__SWIG_8".

 

Another thing needs to be pointed out is that this situation does not occur for every try. For example, the first run failed as above, however, when I tried again without making any modification, then the program can run well. Also, this internal error does not occur at the same place each time it happens.

 

Does anybody have an idea about this problem?Thanks for your help!

Cplex version: IBM ILOG CPLEX Optimization Studio 12.6.2.0

JDK: jdk1.8.0_91

 

BR,

Windy

 

#DecisionOptimization
#OPLusingCPLEXOptimizer

Hi,

could you have an out of memory issue ?

How much memory do you have ?

regards

#DecisionOptimization
#OPLusingCPLEXOptimizer

Originally posted by: windyyy

Hi,

Thank you for answering.

RAM: 32G;

The memory is not a problem because for the same sample size (even very large), some times the model can run well.

For instance, for a certain data set,

the first run, error occurs after 7min,

the second run, error occurs after 3min,

the third run, error occurs after 25min,

the forth run, no error and get the solution.

This problem occurs occationally

 

#DecisionOptimization
#OPLusingCPLEXOptimizer

Hi

1) Can you try with CPLEX 12.6.3 which is the latest version ?

2) Can you try to write cplex.thread=1 in your OPL model and see whether there is some change

3) Are you a business user or a researcher ?

regards

#DecisionOptimization
#OPLusingCPLEXOptimizer

Originally posted by: windyyy

Hi, Thank  you very much for help. 

1) I am trying to get the latest cplex version and after updating it I'll see if there is any improvement;

2) The same error occurs after setting threads parameter as 1;

3) I am a researcher user.

Many thanks :J

___________________________________________________________________________________

Hi, Alex,

 

After CPLEX was updated to 12.6.3, the same probem is still there

Do you have any idea about the information of "at ilog.concert.cppimpl.concert_wrapJNI.new_IloNumVar__SWIG_8(Native Method)" shown in the error notice?

 

Thanks,

Windy

 

#DecisionOptimization
#OPLusingCPLEXOptimizer