[Coin-discuss] Correct use of CglPreProcess with CbcModel?

[John J Forrest]

James,

Could not find a memory leak in preprocessing but did find a major one in
CbcModel so try again.

Dual solution after branch and bound not very useful anyway.  Preferred
method for primal solution is CbcModel::bestSolution()

John Forrest


                                                                           
             "James Gibbons"                                               
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                                       Re: [Coin-discuss] Correct use of   
                                       CglPreProcess with CbcModel?        
             03/29/06 09:14 AM                                             
                                                                           
                                                                           
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Hi John,

I've tried the second way, i.e using:

//strategy and branching
    CbcStrategyDefault strategy(false,10);
    //Set up pre-processing to find sos if wanted
    if (preprocess_) strategy.setupPreProcessing(2);
    model.setStrategy(strategy);

Unfortunately, I still get a memory leak, at roughly the same rate as
before. To check there isn't something wrong elsewhere in my code I've
tried running with everything except the global solve function. Under this
scenario there is no memory leak, which I guess confirms that the problem
is in CbcModel somewhere.

Incidently, using this second approach am I right in thinking that to get
the solution from the CbcModel object (model) back into my original
solver0_  (OsiClpSolverInterface) I have to use:

solver0_->setColSolution(model.getColSolution());
solver0_->setRowPrice(model.getRowPrice());

i.e. it doesn't happen automatically as with CglPreProcess?

Thanks,
James

James,

Try the second way of using CglPreProcess as given in sample2.cpp.  This
uses CbcStrategy and passes that in to Cbcmodel.  So CbcModel handles
copies of solvers.  If that has a memory leak tell me and I will fix.

John Forrest



"James Gibbons" <James.Gibbons at nottingham.ac.uk>
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03/28/2006 08:46 AM
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[Coin-discuss] Correct use of CglPreProcess with CbcModel?






Hi,

I'm having some problems using CglPreProcess and CbcModel together. My
code involves modifying a matrix, solving and changing the many times. My
code works but it leaks memory until eventually all memory is exhausted.
The essentials of the code are at the end of this message (note though
that in my application the LP solve and global solver are in different
functions, and heuristics and cuts are used). To my naive eye it looks
like I need to delete solver1 as preProcess returns a new solver instance,
but this causes a crash. I'm happy to go about things in a different way
if anyone can recommend an alternative. However, CglPreProcess does reduce
the time to find a solution for me so I'd like to keep using it,

Thanks,
James

//code as follows

solver0_(new OsiClpSolverInterface());
solver0_->readLp(filename_.c_str(),1e-08);

for(int i=0;i<numRuns;++i) {

                 //LP solve function
                 solver0_->intitalSolve();

                 //Global solve function
                 CglPreProcess pinfo1;
                 OsiSolverInterface *solver1 =
pinfo1.preProcess(*solver0_,false,15);
                 CbcModel model(*solver1);

                 //add cuts and heuristics to model

                 model.branchAndBound();
                 model.deleteObjects();          //is this necessary?
                 pinfo1.postProcess(*model.solver());
                 //delete solver1;               //causes crash

                 //my update matrix function
                 updateMatrix();
}

delete solver0_;


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