Re: [Boost-users] [mpi] enviroment constructor different from MPI_Init

15 Sep 2009


      On Sep 15, 2009, at 8:12 PM, alfC wrote:
...
I am using MPI in combination with BLACS and apparently it works with
MPI_Init but not with boost.MPI
when I use
#include "blacs.h"
int main(int argc, char* argv[]) {
  MPI_Init(&argc,&argv);
  int nprocs=0;
  int mype=0;
  Cblacs_pinfo( &mype, &nprocs ); // overwrites the pointee, that is
how Cblacs_pinfo works
  std::cout<
the program output (correctly): "0 1"
But when I use
boost::mpi::environment env(argc, argv); //instead of MPI_Init(argc,
argv);
the programs outputs (incorrectly):  "0 -1".
The point being that apparently boost::mpi::environment is not
equivalent to MPI_Init/MPI_Finalize.
Any idea of what is difference between MPI_Init and
boost::mpi::environment?
The constructor is equivalent to the following:

   int flag;
   MPI_Initialized(&flag);
   if (!(flag!=0))
     MPI_Init(&argc, &argv);
   MPI_Errhandler_set(MPI_COMM_WORLD, MPI_ERRORS_RETURN);

Matthias Troyer