Originally posted by: SystemAdmin

Hi All,

I am trying to solve a MIP model once, save its vectors to use as a warm start, then modify some problem data and solve it again. I implemented this using a flow control script, based on the warmstart example. I am running into memory problems when trying to solve the second model: the warm start succeeds but pre solve fails due to an out of memory error. This is particularly strange because this exact problem solves without any memory issues when I run it without a flow control script. I wondered if the problem was a memory management issue, and I am using end() (with mainEndEnabled() on) as often as I can, but this has not changed the memory problem, so either I am not doing this properly or memory management is not the issue. I have included a sample of the code below. Ideas would be very much appreciated!

Thanks!

main {

// get an instance of the main data file
var mainDataFile = new IloOplDataSource("Data_form6_data9.dat");

// create a new scalar data element and add data for first run
var newScalarData = new IloOplDataElements();
newScalarData.TotalWtDelivered_PrevIter = 2046; // add the value for the first iteration

// create a new model for the first run, and add the data
var myOriginalModelDef = thisOplModel.modelDefinition; // get the definition of the existing model
var model1 = new IloOplModel(myOriginalModelDef,cplex); // create a new model
model1.addDataSource(mainDataFile); // add data
model1.addDataSource(newScalarData);

// solve the model
model1.generate();
model1.settings.mainEndEnabled = true;
if ( cplex.solve() ) {
writeln("Running with D' = ",model1.TotalWtDelivered_PrevIter);
writeln("OBJECTIVE: ",cplex.getObjValue());
writeln("Status: ",cplex.getCplexStatus()," (101=optimal,102=opt in tol)");
}
else {
writeln("No solution!");
//break;
}

// save vectors for warm start
var vectors = new IloOplCplexVectors();
if ( vectors.getVectors(cplex) ) {
writeln();
writeln("warm start preparation successful");
} else {
writeln("warm start preparation unsuccessful: ",vectors.status);
}

// update the value for the second run
newScalarData.TotalWtDelivered_PrevIter = model1.TotalWtDelivered

// create a new model to use and add the data
var myNewModel = new IloOplModel(myOriginalModelDef,cplex); // automatically starts from previous basis?
myNewModel.addDataSource(mainDataFile);
myNewModel.addDataSource(newScalarData);

// end the old model
model1.end();

// generate new model
myNewModel.generate();

// try to use warm start
if( vectors.setVectors(cplex) ) {
writeln("warm start ",vectors.Nrows,"x",vectors.Ncols," succeeded ");
} else {
writeln("warm start ",vectors.Nrows,"x",vectors.Ncols," failed: ",vectors.status);
}

// end the vectors
vectors.end();

// solve new model
if ( cplex.solve() ) {
writeln("OBJECTIVE: ",currentObjective);
myNewModel.postProcess();
}
else {
writeln("No solution!");
//break;
}

myNewModel.end();
newScalarData.end();
mainDataFile.end();
cplex.end();
}
#DecisionOptimization
#OPLusingCPLEXOptimizer