Intel® oneAPI HPC Toolkit
Get help with building, analyzing, optimizing, and scaling high-performance computing (HPC) applications.
2060 Discussions

MPI_Recv Hangs While Receiving Large Array


I'm noticing some strange behaviour with a very simple piece of MPI code:

#include <mpi.h>

int main(int argc, char* argv[])
    // Initialize the MPI environment
    MPI_Init(NULL, NULL);

    int world_rank;
    MPI_Comm_rank(MPI_COMM_WORLD, &world_rank);
    int world_size;
    MPI_Comm_size(MPI_COMM_WORLD, &world_size);

    // We are assuming at least 2 processes for this task
    if (world_size != 2)
        std::cout << "World size must be equal to 1" << std::endl;
        MPI_Abort(MPI_COMM_WORLD, 1);

    int numberCounter = 10000;
    double number[numberCounter];

    if (world_rank == 0)
        std::cout << world_rank << std::endl;
        MPI_Send(number, numberCounter, MPI_DOUBLE, 1, 0, MPI_COMM_WORLD);
    else if (world_rank == 1)
        std::cout << world_rank << std::endl;
        MPI_Recv(number, numberCounter, MPI_DOUBLE, 0, 0, MPI_COMM_WORLD, MPI_STATUS_IGNORE);


The above works fine provided that numberCounter is small (~1000). When the value is larger however (>10000), the code hangs and never reaches the end. I checked with MPI_Iprobe and it does show that rank 1 is receiving a message, but MPI_Recv always hangs.

What could be causing this? Can anyone else reproduce this behaviour?

[EDIT] I'm not sure how I missed this, but this seems to be a duplicate of [/EDIT]

0 Kudos
0 Replies