[Cbc-tickets] [COIN-OR Branch-and-Cut MIP Solver] #120: Crash in presolve

[COIN-OR Branch-and-Cut MIP Solver]

#120: Crash in presolve
-------------------+--------------------------------------------------------
Reporter:  falk    |       Owner:  tkr
    Type:  defect  |      Status:  new
Priority:  major   |   Component:  Cbc
 Version:  trunk   |    Keywords:     
-------------------+--------------------------------------------------------
 with current SVN, I see crashes in presolve. Here is an example:

 {{{
 #include <coin/OsiClpSolverInterface.hpp>
 #include <coin/CbcModel.hpp>
 #include <coin/CbcStrategy.hpp>

 int main() {
   OsiClpSolverInterface clp;

   for (int i = 0; i < 3; i++) {
     clp.addCol(0, NULL, NULL, 0.0, 1.0, 1.0);
     clp.setInteger(i);
   }

   int indices1[2] = {1, 2};
   double values1[2] = {1.0, 1.0 };
   clp.addRow(2, indices1, values1, 1.0, COIN_DBL_MAX);
   int indices2[2] = {0, 2};
   double values2[2] = {1.0, 1.0, };
   clp.addRow(2, indices2, values2, 1.0, COIN_DBL_MAX);
   int indices3[2] = {0, 1};
   double values3[2] = {1.0, 1.0, };
   clp.addRow(2, indices3, values3, 1.0, COIN_DBL_MAX);

   CbcModel model(clp);

   CbcStrategyDefault strategy;
   strategy.setupPreProcessing(1);
   model.setStrategy(strategy);
   model.initialSolve();
   model.branchAndBound();

   return 0;
 }
 }}}

 {{{
 falk at baltrum:/tmp% g++ test2.cc -I/home/falk/opt/cbc/include
 -L/home/falk/opt/cbc/lib -lpthread -lCbcSolver -lCbc -lCgl -lClp
 -lCoinUtils -lOsiClp -lOsi -lz -lrt -lbz2 && ./a.out
 Coin0506I Presolve 3 (0) rows, 3 (0) columns and 6 (0) elements
 Clp0006I 0  Obj 0 Primal inf 2.9999997 (3)
 Clp0006I 3  Obj 1.5
 Clp0000I Optimal - objective value 1.5
 Clp0032I Optimal objective 1.5 - 3 iterations time 0.002
 Clp0000I Optimal - objective value 1.5
 Clp0006I 0  Obj 1.5
 Clp0006I 0  Obj 1.5
 Clp0000I Optimal - objective value 1.5
 Clp0006I 0  Obj 1.5 Primal inf 0.4999999 (1) Dual inf 3e+08 (3)
 Clp0029I End of values pass after 3 iterations
 Clp0006I 3  Obj 2
 Clp0006I 3  Obj 2
 Clp0000I Optimal - objective value 2
 zsh: segmentation fault  ./a.out
 }}}

 valgrind shows the following problem:

 {{{
 ==27977== Invalid read of size 4
 ==27977==    at 0x5D2EBA8:
 CoinPackedMatrix::CoinPackedMatrix(CoinPackedMatrix const&, int, int,
 bool) (in /home/falk/opt/cbc-2.7/lib/libCoinUtils.so.0.0.0)
 ==27977==    by 0x56D12F4:
 CglProbing::gutsOfGenerateCuts(OsiSolverInterface const&, OsiCuts&,
 double*, double*, double*, double*, CglTreeInfo*) const
 (CglProbing.cpp:2040)
 ==27977==    by 0x56D4C24:
 CglProbing::generateCutsAndModify(OsiSolverInterface const&, OsiCuts&,
 CglTreeInfo*) (CglProbing.cpp:1357)
 ==27977==    by 0x56A3754: CglPreProcess::modified(OsiSolverInterface*,
 bool, int&, int, int) (CglPreProcess.cpp:3916)
 ==27977==    by 0x56AA559:
 CglPreProcess::preProcessNonDefault(OsiSolverInterface&, int, int, int)
 (CglPreProcess.cpp:2356)
 ==27977==    by 0x5111AF7: CbcStrategyDefault::setupOther(CbcModel&)
 (CbcStrategy.cpp:521)
 ==27977==    by 0x50F8198: CbcModel::branchAndBound(int) (in
 /home/falk/opt/cbc-2.7/lib/libCbc.so.0.0.0)
 ==27977==    by 0x400F1F: main (cbc-crash2.cc:29)
 ==27977==  Address 0x7b640c4 is 4 bytes after a block of size 0 alloc'd
 ==27977==    at 0x4C26CF7: operator new[](unsigned long) (in
 /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
 ==27977==    by 0x5D2E93C:
 CoinPackedMatrix::CoinPackedMatrix(CoinPackedMatrix const&, int, int,
 bool) (in /home/falk/opt/cbc-2.7/lib/libCoinUtils.so.0.0.0)
 ==27977==    by 0x56D12F4:
 CglProbing::gutsOfGenerateCuts(OsiSolverInterface const&, OsiCuts&,
 double*, double*, double*, double*, CglTreeInfo*) const
 (CglProbing.cpp:2040)
 ==27977==    by 0x56D4C24:
 CglProbing::generateCutsAndModify(OsiSolverInterface const&, OsiCuts&,
 CglTreeInfo*) (CglProbing.cpp:1357)
 ==27977==    by 0x56A3754: CglPreProcess::modified(OsiSolverInterface*,
 bool, int&, int, int) (CglPreProcess.cpp:3916)
 ==27977==    by 0x56AA559:
 CglPreProcess::preProcessNonDefault(OsiSolverInterface&, int, int, int)
 (CglPreProcess.cpp:2356)
 ==27977==    by 0x5111AF7: CbcStrategyDefault::setupOther(CbcModel&)
 (CbcStrategy.cpp:521)
 ==27977==    by 0x50F8198: CbcModel::branchAndBound(int) (in
 /home/falk/opt/cbc-2.7/lib/libCbc.so.0.0.0)
 ==27977==    by 0x400F1F: main (cbc-crash2.cc:29)
 ==27977==

 }}}

 Maybe there is a problem with the matrix becoming zero-sized.

-- 
Ticket URL: <https://projects.coin-or.org/Cbc/ticket/120>
COIN-OR Branch-and-Cut MIP Solver <http://projects.coin-or.org/Cbc>
An LP-based branch-and-cut MIP solver.