mpich/examples/developers/threads.c

/*
 * Copyright (C) by Argonne National Laboratory
 *     See COPYRIGHT in top-level directory
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <pthread.h>
#include <sched.h>

#include "mpi.h"

void *thrdsub(void *arg);

int comm_rank, comm_size, thread_level_provided, num_msgs = 50;
pthread_mutex_t mpi_lock = PTHREAD_MUTEX_INITIALIZER;

int main(int argc, char *argv[])
{
    int i, rc, thrdrank[4] = { 0, 1, 2, 3 };
    pthread_t thrdid[4];

    setbuf(stdout, NULL);

    rc = MPI_Init_thread(&argc, &argv, MPI_THREAD_MULTIPLE, &thread_level_provided);
    if (rc != MPI_SUCCESS) {
        printf("MPI_Init_thread failed with rc=%d\n", rc);
        exit(-1);
    }
    MPI_Comm_rank(MPI_COMM_WORLD, &comm_rank);
    MPI_Comm_size(MPI_COMM_WORLD, &comm_size);
    if (comm_size != 2) {
        printf("**** please run me with exactly 2 processes\n");
        exit(-1);
    }

    switch (thread_level_provided) {
        case MPI_THREAD_SINGLE:
            printf("thread level supported: MPI_THREAD_SINGLE\n");
            break;
        case MPI_THREAD_FUNNELED:
            printf("thread level supported: MPI_THREAD_FUNNELED\n");
            break;
        case MPI_THREAD_SERIALIZED:
            printf("thread level supported: MPI_THREAD_SERIALIZED\n");
            break;
        case MPI_THREAD_MULTIPLE:
            printf("thread level supported: MPI_THREAD_MULTIPLE\n");
            break;
        default:
            printf("thread level supported: UNRECOGNIZED\n");
            exit(-1);
    }

    for (i = 0; i < 3; i++) {
        rc = pthread_create(&thrdid[i], (void *) NULL, (void *) thrdsub, (void *) &thrdrank[i]);
        if (rc < 0) {
            printf("create of thread failed with rc=%d\n", rc);
            exit(-1);
        }
    }
    for (i = 0; i < 3; i++) {
        pthread_join(thrdid[i], NULL);
    }

    MPI_Finalize();
    exit(0);
}

void *thrdsub(void *arg)
{
    int mythrdrank, num_sent;
    char s_buff[1024] = "hello", r_buff[1024];
    MPI_Status status;

    mythrdrank = *((int *) arg);
    printf("comm_rank=%d mythrdrank=%d\n", comm_rank, mythrdrank);
    if (thread_level_provided == MPI_THREAD_SINGLE || thread_level_provided == MPI_THREAD_FUNNELED) {
        if (mythrdrank > 0)
            pthread_exit(NULL);
    }
    for (num_sent = 0; num_sent < num_msgs; num_sent++) {
        if (comm_rank == 0) {
            if (thread_level_provided == MPI_THREAD_SINGLE ||
                thread_level_provided == MPI_THREAD_FUNNELED) {
                pthread_mutex_lock(&mpi_lock);
            }
            MPI_Send(s_buff, strlen(s_buff) + 1, MPI_CHAR, 1, mythrdrank, MPI_COMM_WORLD);
            r_buff[0] = '\0';
            MPI_Recv(r_buff, 1024, MPI_CHAR, 1, mythrdrank, MPI_COMM_WORLD, &status);
            if (strcmp(s_buff, r_buff) != 0) {
                printf("comm_rank=%d mythrdrank=%d bad recv\n", comm_rank, mythrdrank);
            }
            if (thread_level_provided == MPI_THREAD_SINGLE ||
                thread_level_provided == MPI_THREAD_FUNNELED) {
                pthread_mutex_unlock(&mpi_lock);
            }
        } else {
            if (thread_level_provided == MPI_THREAD_SINGLE ||
                thread_level_provided == MPI_THREAD_FUNNELED) {
                pthread_mutex_lock(&mpi_lock);
            }
            r_buff[0] = '\0';
            MPI_Recv(r_buff, 1024, MPI_CHAR, 0, mythrdrank, MPI_COMM_WORLD, &status);
            if (strcmp(s_buff, r_buff) != 0) {
                printf("comm_rank=%d mythrdrank=%d bad recv\n", comm_rank, mythrdrank);
            }
            MPI_Send(s_buff, strlen(s_buff) + 1, MPI_CHAR, 0, mythrdrank, MPI_COMM_WORLD);
            if (thread_level_provided == MPI_THREAD_SINGLE ||
                thread_level_provided == MPI_THREAD_FUNNELED) {
                pthread_mutex_unlock(&mpi_lock);
            }
        }
        /* printf("sent and recvd\n"); */
    }
    return (NULL);
}