source: CIVL/examples/mpi/mpiFeature/input_branch_good.c

/* Example where the deadlock depends on a (command line) input.
 * It deadlocks when the commandline input equals to two.
 * Run with nprocs=2.
 */
#include <mpi.h>
#include <stdlib.h>
#define comm MPI_COMM_WORLD

int main(int argc, char * argv[]) {
  int rank;
  
  MPI_Init(&argc, &argv);
  MPI_Comm_rank(MPI_COMM_WORLD, &rank);
  
  if (rank == 0)
    if (atoi(argv[1]) != 2) {
      MPI_Send(NULL, 0, MPI_INT, 1, 0, comm);
    } else  {
      MPI_Send(NULL, 0, MPI_INT, 1, 0, comm);
    }
  if (rank == 1)
    MPI_Recv(NULL, 0, MPI_INT, 0, 0, comm, MPI_STATUS_IGNORE);
  MPI_Finalize();
}