root/orte/test/mpi/concurrent_spawn.c

DEFINITIONS

1. main

   1 #define _GNU_SOURCE
   2 #include "orte_config.h"
   3 
   4 #include <stdio.h>
   5 #include <sys/types.h>
   6 #include <unistd.h>
   7 #include <stdlib.h>
   8 
   9 #include <mpi.h>
  10 
  11 #define NUM_CHILDREN 5
  12 
  13 int main(int argc, char* argv[])
  14 {
  15     int msg;
  16     MPI_Comm parent, children[NUM_CHILDREN];
  17     int rank, size, i;
  18     char hostname[OPAL_MAXHOSTNAMELEN];
  19     pid_t pid;
  20     char *child_argv[2] = { "", NULL };
  21 
  22     MPI_Init(NULL, NULL);
  23     MPI_Comm_rank(MPI_COMM_WORLD, &rank);
  24     MPI_Comm_size(MPI_COMM_WORLD, &size);
  25     MPI_Comm_get_parent(&parent);
  26     /* If we get COMM_NULL back, then we're the parent */
  27     if (MPI_COMM_NULL == parent) {
  28         pid = getpid();
  29 
  30         /* First, spawn all the children.  Give them an argv
  31            identifying which child they are */
  32         for (i = 0; i < NUM_CHILDREN; ++i) {
  33             printf("Parent [pid %ld] about to spawn child #%d\n",
  34                    (long)pid, i);
  35             opal_asprintf(&(child_argv[0]), "%d", i);
  36             MPI_Comm_spawn(argv[0], child_argv, 1, MPI_INFO_NULL,
  37                            0, MPI_COMM_WORLD, &children[i],
  38                            MPI_ERRCODES_IGNORE);
  39             printf("Parent done with spawn of child %d\n", i);
  40         }
  41 
  42         /* Now send each of the children a message */
  43         if (0 == rank) {
  44             for (i = 0; i < NUM_CHILDREN; ++i) {
  45                 printf("Parent sending message to child %d\n", i);
  46                 MPI_Send(&i, 1, MPI_INT, 0, 1, children[i]);
  47             }
  48         }
  49 
  50         /* Now disconnect from each of the children */
  51         for (i = 0; i < NUM_CHILDREN; ++i) {
  52             printf("Parent disconnecting from child %d\n", i);
  53             MPI_Comm_disconnect(&children[i]);
  54             printf("Parent disconnected from child %d\n", i);
  55         }
  56     }
  57     /* Otherwise, we're the child */
  58     else {
  59         gethostname(hostname, sizeof(hostname));
  60         if (argc == 1) {
  61             printf("ERROR: child did not receive exepcted argv!\n");
  62             i = -1;
  63         } else {
  64             i = atoi(argv[1]);
  65         }
  66         pid = getpid();
  67         printf("Hello from the child %d on host %s pid %ld\n", i, hostname, (long)pid);
  68         if (0 == rank) {
  69             MPI_Recv(&msg, 1, MPI_INT, 0, 1, parent, MPI_STATUS_IGNORE);
  70             printf("Child %d received msg: %d\n", i, msg);
  71             if (i != msg) {
  72                 printf("ERROR: Child %d got wrong message (got %d, expected %d)\n",
  73                        i, msg, i);
  74             }
  75         }
  76         MPI_Comm_disconnect(&parent);
  77         printf("Child %d disconnected\n", i);
  78     }
  79 
  80     MPI_Finalize();
  81     return 0;
  82 }