On Jun 8, 2012, at 6:43 AM, BOUVIER Benjamin wrote:
> # include <mpi.h>
> # include <stdio.h>
> # include <string.h>
>
> int main(int argc, char **argv)
> {
> int rank, size;
> const char someString[] = "Can haz cheezburgerz?";
>
> MPI_Init(&argc, &argv);
>
> MPI_Comm_rank( MPI_COMM_WORLD, & rank );
> MPI_Comm_size( MPI_COMM_WORLD, & size );
>
> if ( rank == 0 )
> {
> int len = strlen( someString );
> int i;
> for( i = 1; i < size; ++i)
> {
> MPI_Send( &len, 1, MPI_INT, i, 0, MPI_COMM_WORLD );
> MPI_Send( &someString, len+1, MPI_CHAR, i, 0, MPI_COMM_WORLD );
> }
> } else {
> char buffer[ 128 ];
> int receivedLen;
> MPI_Status stat;
> MPI_Recv( &receivedLen, 1, MPI_INT, 0, 0, MPI_COMM_WORLD, &stat );
> printf( "[Worker] Length : %d\n", receivedLen );
> MPI_Recv( buffer, receivedLen+1, MPI_CHAR, 0, 0, MPI_COMM_WORLD,
> &stat);
> printf( "[Worker] String : %s\n", buffer );
> }
>
> MPI_Finalize();
> }
I don't see anything obviously wrong with this code.
> I know that there is a better way to send a string, by giving a maximum
> buffer size at the second MPI_Recv, but there is no the main topic here.
> The launch works locally (i.e when the 2 processes are launched on one
> machine), but doesn't work when the 2 processes are dispatched in 2 machines
> through network (i.e one per host). In this case, the worker correctly reads
> the INT, and then master and worker block on the next call.
That's very odd.
> I have no issue when sending only char strings or only numbers. This only
> happens when sending char strings then numbers, or in the other order.
That's even more odd.
Can you run standard benchmarks like MPI net pipe, and/or the OSU benchmarks?
(across multiple nodes, that is)
--
Jeff Squyres
jsquy...@cisco.com
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