[Cbc] API crashes while standalone does not (follow up)

[Alexis Guigue]

Hi all,

I have been pursuing my investigations.

My original code was

OsiClpSolverInterface osiClpSolver;

....

  try {
      callCbc("-solve -quit", cbcSolver);
  }
  catch (CoinError e) {
      e.print();
      std::cout << "Crashing....\n";
      if (e.lineNumber() >= 0) std::cout << "This was from a CoinAssert" 
<< std::endl;
      exit(EXIT_FAILURE);
  }

It was working fine until I started to increase the size of the test 
cases -> (40000 variables, 5000 constraints). Then, it suddendly
started to crash right in the middle of the optimization. Note that I am 
not actually doing really anything to osiClpSolver. I am
just populating a matrix, so no special cutting, branching, etc.. 
implemented. Really nothing fancy.

Then, I added the lines where .... are

osiClpSolver.writeLp("test","lp");
osiClpSolver.writeMps("test","mps");

to save the model in the files test.lp and test.mps. When I run the 
standalone CBC either with test.lp or test.mps, it does
not crash and produces the optimal solution.

Q: I am a bit surprised that the optimal value is not the same, but I 
suspect it might related to the precision while reading/writing
the file. Am I right? How can this be fixed?

I have tried the following thing (kind of weird, but it is debugging 
after all). In my code, I save the file and reload right away, so
it looks like this

OsiClpSolverInterface osiClpSolver;

...

osiClpSolver.writeMps("test","mps");

  // Test
OsiClpSolverInterface solver1;
solver1.readMps("test","mps");
callCbc("-solve -quit", solver1);

/*
try {
      callCbc("-solve -quit", cbcSolver);
  }
  catch (CoinError e) {
      e.print();
      std::cout << "Crashing....\n";
      if (e.lineNumber() >= 0) std::cout << "This was from a CoinAssert" 
<< std::endl;
      exit(EXIT_FAILURE);
  }
*/

It is the closest I can get to the standalone version and it crashes 
too. What do you think? Any ideas?

I noticed that the standalone is based on the version 2.7.1, whereas I 
am using 2.7.2. So, I am moving
my code to using version 2.7.1. I will keep you posted on my results. 
Also, could 32 bits vs 64 bits be a factor?

Thanks

Cheers

Alexis

-- 
Software Engineer/Research Engineer
Softree Technical Systems Inc.
www.softree.com
Engineering an Easier Way