Rookie HPC

About

Docs

Tools

Tests

MPI_Ssend

Definition

MPI_Ssend stands for MPI Synchronous Send; sending a message in a blocking synchronous fashion. The routine returns upon completion, which is reached when the recipient receives the message after having posted the corresponding MPI receive (see MPI_Recv and MPI_Irecv). This routine may be invoked implicitly by the default MPI send (MPI_Send). Refer to MPI_Issend to see the non-blocking counterpart of this routine. Other blocking sends are MPI_Send, MPI_Bsend and MPI_Rsend.

Copy

Feedback

int MPI_Ssend(const void* buffer,
              int count,
              MPI_Datatype datatype,
              int recipient,
              int tag,
              MPI_Comm communicator);

Parameters

buffer
The buffer to send.
count
The number of elements to send.
datatype
The type of one buffer element.
recipient
The rank of the recipient MPI process.
tag
The tag to apply to the message.
communicator
The communicator in which the communication takes place.

Returned value

MPI_SUCCESS
The routine successfully completed.

Example

Copy

Feedback

#include <stdio.h>
#include <stdlib.h>
#include <mpi.h>

/**
 * @brief Illustrates how to send a message in a blocking synchronous fashion.
 * @details This program is meant to be run with 2 processes: a sender and a
 * receiver.
 **/
int main(int argc, char* argv[])
{
    MPI_Init(&argc, &argv);

    // Get the number of processes and check only 2 processes are used
    int size;
    MPI_Comm_size(MPI_COMM_WORLD, &size);
    if(size != 2)
    {
        printf("This application is meant to be run with 2 processes.\n");
        MPI_Abort(MPI_COMM_WORLD, EXIT_FAILURE);
    }

    // Get my rank and do the corresponding job
    enum role_ranks { SENDER, RECEIVER };
    int my_rank;
    MPI_Comm_rank(MPI_COMM_WORLD, &my_rank);
    switch(my_rank)
    {
        case SENDER:
        {
            // The "master" MPI process issues the MPI_Ssend.
            int buffer_sent = 12345;
            MPI_Request request;
            printf("MPI process %d sends value %d.\n", my_rank, buffer_sent);
            MPI_Ssend(&buffer_sent, 1, MPI_INT, RECEIVER, 0, MPI_COMM_WORLD);
            break;
        }
        case RECEIVER:
        {
            // The "slave" MPI process receives the message.
            int received;
            MPI_Recv(&received, 1, MPI_INT, SENDER, 0, MPI_COMM_WORLD, MPI_STATUS_IGNORE);
            printf("MPI process %d received value: %d.\n", my_rank, received);
            break;
        }
    }

    MPI_Finalize();

    return EXIT_SUCCESS;
}