How do I do finish all processes and then do serial work in C using MPI?-CodePudding

I have written a multithreaded C program using MPI to find palidromes in a 2D char array. I start 4 threads. Now after all threads are finished, I want to kill the threads and continue serial work? How do I achieve this? The code looks something like this:

int main(int argc, char *argv[]) {
    // define some varibles
    int foo;

    // Kick off parallel work
    MPI_Init (&argc, &argv);
    MPI_Comm_size(MPI_COMM_WORLD, &size); 
    MPI_Comm_rank(MPI_COMM_WORLD, &rank); 

    if (rank == 0) {
        // some work ...
    }
    if (rank == 1) {
        // some work ...
    }
    if (rank == 2) {
        // some work ...
    }
    if (rank == 3) {
        // some work ...
    }

    MPI_Finalize();

    // Here I want to print some results AFTER all threads are finished. E.g deallocate memory etc
    printf("Found: %d", foo);

    return 0;
}

CodePudding user response：

You're confused about how MPI works. MPI does not use threads, it uses independent processes. Each process executes the whole of the main program.* So if you want only one process to do work, you have put a condition if (i_am_working_process) around that code.

*footnote: The standard actually allows different models, but in practice this is true.