[Cbc] Segfault / memory corruption after "assignSolver" in "CbcModel"

[John Forrest]

Dirk,

The -cpp was a nice idea - but impossible to keep current - so something 
may be broken.

Try using code from the Cbc/examples driver3.cpp or driver4.cpp which 
should give you the same flexibility.

John Forrest
On 07/05/14 11:18, Dirk Eßer wrote:
> Hello,
>
> I have a little problem adding a preprocessing step to program doing 
> MIP solving using the CBC library. The problem is, that the program 
> fails with more or less random memory corruption (and in the better 
> cases: with a segfault) some of the time.
>
> The CbcModel instance is created programmatically
>
>     OsiClpSolverInterface iface;
>     CoinPackedMatrix pmx(false, num_columns, num_rows, num_elements,
>     matrix, columns, starts, lengths);
>
>     iface.setObjSense(-1.0);
>     iface.loadProblem(pmx, 0, 0, objective, senses, rights, 0);
>     iface.passInMessageHandler(&printer);
>
>     model_ptr LP(new CbcModel(iface));
>     ... adding stuff via LP->addObjects(...) to declare integer
>     constraints on variables and a few SOSes ...
>
> Things work fine, if we directly compute a solution without further 
> preprocessing via
>
>     LP->initialSolve();
>     LP->branchAndBound();
>
> We now try to add a pre-processing step to the solution process. As a 
> starting point, we used the driver code generated by the CBC command 
> line tool ("-cpp 0", which doesn't compile).
>
>     OsiSolverInterface* original_solver = LP->solver();
>     OsiSolverInterface* cloned_solver = original_solver->clone();
>     OsiSolverInterface* configured_solver = 0;
>
>     cloned_solver->passInMessageHandler(LP->messageHandler());
>     cloned_solver->setHintParam(OsiDoInBranchAndCut, true, OsiHintDo);
>
>     CglPreProcess processor;
>
>                 {
>                     CglProbing prober;
>                     prober.setUsingObjective(1);
>                     prober.setMaxPass(3);
>     prober.setMaxProbeRoot(cloned_solver->getNumCols());
>                     prober.setMaxElements(100);
>                     prober.setMaxLookRoot(50);
>                     prober.setRowCuts(3);
>                     processor.addCutGenerator(&prober);
>                 }
>
>     configured_solver = processor.preProcessNonDefault(*cloned_solver,
>     2, 10);
>
>     cloned_solver->setHintParam(OsiDoInBranchAndCut, false, OsiHintDo);
>
>     if (!configured_solver)
>     {
>         delete cloned_solver;
>         return status::infeasible;
>     }
>
>     configured_solver->setHintParam(OsiDoInBranchAndCut, false,
>     OsiHintDo);
>
>     OsiSolverInterface* configured_clone = configured_solver->clone();
>
>     LP->assignSolver(configured_clone, true /* Kill previous solver
>     */); /*-- XXX --*/
>     LP->initialSolve();
>     LP->branchAndBound();
>
>     int n_cols = cloned_solver->getNumCols();
>     processor.postProcess(*LP->solver());
>
>     LP->assignSolver(cloned_solver, true /* Kill previous solver */);
>     memcpy(LP->bestSolution(), LP->solver()->getColSolution(), n_cols
>     * sizeof(double));
>
> It seems, that we are violating one or two unwritten laws of memory 
> management with CBC, but I am at loss as what we are doing wrong here. 
> Any help, hints, pointer to documentation, etc. is highly appreciated.
>
> Cheers,
> Dirk Eßer
>
>
> _______________________________________________
> Cbc mailing list
> Cbc at list.coin-or.org
> http://list.coin-or.org/mailman/listinfo/cbc

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://list.coin-or.org/pipermail/cbc/attachments/20140507/a1afcf6f/attachment.html>