我为我的家庭作业（并行编程）编写了这个程序，但我在运行时遇到了一些错误。
这是来源：
/****************************************
* Program: *
* ALL_TO_ALL_BROADCAST_MESH *
* *
* Author: *
* ------------------- *
* ------------------- *
****************************************/
/*
* Program's using MPI_Send, MPI_Recv and cartesian topology functions
*
* Compile using: mpicc -o all_to_all_bc all_to_all_bc.c
*/
#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#include <string.h>
#include "mpi.h"
/* Number of dimensions */
#define NUMB_DIMS 2
/* Max value for the rand() function */
#define MAX_NUMB 128
#define TRUE 1
#define FALSE 0
/* Checks if square root of n can be calculated *
* Returns the square root on success or -1 on failure */
int is_sqrt(int n);
int main(int argc, char **argv) {
int my_rank; /* Rank of the current process */
int size; /* Number of processes in the mesh */
int mesh_size; /* Size of a single mesh row */
int my_numb; /* Message */
int *all_numbs; /* All numbers owned by the current process */
int numb_numbs; /* Number of numbers in the all_numbs array */
int left, right, up, down; /* Neighbourghs of the process as rank numbers */
/* Neighbourghs as cartesian coords */
int *my_coords, *left_coords, *right_coords, *up_coords, *down_coords;
/* Allocate memory for cartesian coords */
my_coords = (int *)malloc(NUMB_DIMS*sizeof(int));
left_coords = (int *)malloc(NUMB_DIMS*sizeof(int));
right_coords = (int *)malloc(NUMB_DIMS*sizeof(int));
up_coords = (int *)malloc(NUMB_DIMS*sizeof(int));
down_coords = (int *)malloc(NUMB_DIMS*sizeof(int));
MPI_Comm grid_comm; /* Mesh Communicator */
int *dim_size = (int *)malloc(NUMB_DIMS*sizeof(int)); /* Sizes of mesh dimensions */
int *peroids = (int *)malloc(NUMB_DIMS*sizeof(int)); /* True if the column wraps around */
int reorder; /* I have no idea what this does ;) */
int i,j; /* counters */
/* MPI initialization */
MPI_Init(&argc,&argv);
MPI_Comm_size(MPI_COMM_WORLD,&size);
MPI_Comm_rank(MPI_COMM_WORLD,&my_rank);
/* Check if p^2=N */
if (mesh_size=is_sqrt(size)<0) {
perror("Square root of the number of processes can't be calculated!");
MPI_Finalize();
return -1;
}
/* Configure parameters for MPI_Cart_Create() */
for (i=0;i<NUMB_DIMS;i++) {
dim_size[i]=mesh_size;
peroids[i]=TRUE;
}
reorder=FALSE;
/* create new communicator */
if (MPI_Cart_create(MPI_COMM_WORLD,NUMB_DIMS,dim_size,peroids,reorder,&grid_comm)<0) {
perror("Unable to create new communicator!");
MPI_Finalize();
return -1;
}
/* calculate the coords and ranks */
MPI_Cart_coords(grid_comm,my_rank,NUMB_DIMS,my_coords);
/* !!this block is for 2D grid only!! */
memcpy(left_coords,my_coords,NUMB_DIMS*sizeof(int));
memcpy(right_coords,my_coords,NUMB_DIMS*sizeof(int));
memcpy(up_coords,my_coords,NUMB_DIMS*sizeof(int));
memcpy(down_coords,my_coords,NUMB_DIMS*sizeof(int));
left_coords[0]=(left_coords[0]-1)%mesh_size;
right_coords[0]=(right_coords[0]+1)%mesh_size;
up_coords[1]=(up_coords[1]+1)%mesh_size;
down_coords[1]=(down_coords[1]-1)%mesh_size;
MPI_Cart_rank(grid_comm,left_coords,&left);
MPI_Cart_rank(grid_comm,right_coords,&right);
MPI_Cart_rank(grid_comm,up_coords,&up);
MPI_Cart_rank(grid_comm,down_coords,&down);
/* !!this block is for 2D grid only!! */
/* get a random number for this process */
my_numb = rand()%MAX_NUMB;
all_numbs = (int *)malloc(size*sizeof(int));
MPI_Status status;
/****************
* BROADCASTING *
****************/
printf("I'm process (%d,%d),\nMy number is %d\n\n",my_coords[0],my_coords[1],my_numb);
all_numbs[0]=my_numb;
numb_numbs=1;
/* Communication along rows */
for (i=0;i<mesh_size-1;i++) {
printf("I'm process (%d,%d),\nI'm sending %d to process (%d,%d)\n\n",my_coords[0],my_coords[1],my_numb,right_coords[0],right_coords[1]);
MPI_Send(&my_numb,sizeof(int),MPI_INT,right,99,grid_comm);
printf("I'm process (%d,%d),\nI'm recieving data from process (%d,%d)\n\n",my_coords[0],my_coords[1],left_coords[0],left_coords[1]);
MPI_Recv(&my_numb,sizeof(int),MPI_INT,left,99,grid_comm,&status);
all_numbs[numb_numbs]=my_numb;
numb_numbs++;
printf("My current numbers are:\n");
for (j=0;j<numb_numbs;j++)
printf("%d, ",all_numbs[j]);
printf("\n\n");
}
/* Communication along columns */
my_numb=all_numbs[0];
for (i=0;i<mesh_size-1;i++) {
printf("I'm process (%d,%d),\nI'm sending %d to process (%d,%d)\n\n",my_coords[0],my_coords[1],my_numb,up_coords[0],up_coords[1]);
MPI_Send(&my_numb,sizeof(int),MPI_INT,up,99,grid_comm);
printf("I'm process (%d,%d),\nI'm recieving data from process (%d,%d)\n\n",my_coords[0],my_coords[1],down_coords[0],down_coords[1]);
MPI_Recv(&my_numb,sizeof(int),MPI_INT,down,99,grid_comm,&status);
all_numbs[numb_numbs]=my_numb;
numb_numbs++;
printf("My current numbers are:\n");
for (j=0;j<numb_numbs;j++)
printf("%d, ",all_numbs[j]);
printf("\n\n");
}
printf("I'm process %d\nBroacasting performed!\nMy numbers are:\n");
for (i=0;i<numb_numbs;i++)
printf("%d, ",all_numbs[i]);
printf("\n\n");
MPI_Finalize();
return 0;
}
int is_sqrt(int n) {
double a=n;
double b=sqrt(a);
double c=b*b;
int result;
if (a==c) {
result=(int)b;
return result;
}
else
return -1;
}
这是我得到的错误：
% mpirun -np 4 all_to_all_bc
[cli_1]: [cli_3]: aborting job:
Fatal error in MPI_Cart_coords: Invalid communicator, error stack:
MPI_Cart_coords(130): MPI_Cart_coords(MPI_COMM_NULL, rank=3, maxdims=2, coords=0x6a9010) failed
MPI_Cart_coords(74).: Null communicator
aborting job:
Fatal error in MPI_Cart_coords: Invalid communicator, error stack:
MPI_Cart_coords(130): MPI_Cart_coords(MPI_COMM_NULL, rank=1, maxdims=2, coords=0x6a9010) failed
MPI_Cart_coords(74).: Null communicator
[cli_0]: aborting job:
Fatal error in MPI_Cart_coords: Invalid communicator, error stack:
MPI_Cart_coords(130): MPI_Cart_coords(MPI_COMM_NULL, rank=0, maxdims=2, coords=0x6a9010) failed
MPI_Cart_coords(74).: Null communicator
[cli_2]: aborting job:
Fatal error in MPI_Cart_coords: Invalid communicator, error stack:
MPI_Cart_coords(130): MPI_Cart_coords(MPI_COMM_NULL, rank=2, maxdims=2, coords=0x6a9010) failed
MPI_Cart_coords(74).: Null communicator
rank 3 in job 18 ---host---_58157 caused collective abort of all ranks
exit status of rank 3: killed by signal 9
rank 2 in job 18 ---host---_58157 caused collective abort of all ranks
exit status of rank 2: return code 1
rank 1 in job 18 ---host---_58157 caused collective abort of all ranks
exit status of rank 1: killed by signal 9
rank 0 in job 18 ---host---_58157 caused collective abort of all ranks
exit status of rank 0: return code 1