Dear open-mpi users:

 

I come across a little problem when running a MPI C program compiled with Open MPI 1.4.3. A part of codes as follows:

 

    MPI_Init(&argc, &argv);

    MPI_Comm_size(MPI_COMM_WORLD, &numprocs);
    MPI_Comm_rank(MPI_COMM_WORLD, &myid);

    MPI_Get_processor_name(processor_name, &namelen);

    if (myid == 0) {
         printf("Please give N= ");
         //fflush(stdout);
         scanf("%d", &n);
         startwtime = MPI_Wtime();
     }

 

If comment out the sentence of "fflush(stdout);", it doesn't print out the message till I input an integer n. And if I add the fflush function between them, it works as expected, though comsumming time obviously.

 

However, when I compiled it with Mpich2-1.3.2p1, without fflush function in the code, it works correctly.

 

Can anyone know what the matter is.

 

Thanks!

--

Meilin Bai