任何人都能说出我做错了什么，因为我收到了这个错误。 代码：
#include<stdio.h>
#include<mpi.h>
void transpose(int ** p, int row, int col)
{
int ** tempVar;
tempVar = (int *)malloc(sizeof(int *)* row);
int i = 0;
for (; i < row; i++)
{
tempVar[i] = (int *)malloc(sizeof (int *)* col);
int j = 0;
while (j < col)
{
tempVar[i][j] = p[j][i];
j++;
}
}
p = tempVar;
}
void main(int argc, char * argv[])
{
int rank, size;
MPI_Init(argc, argv);
MPI_Comm_rank(MPI_COMM_WORLD, &rank);
MPI_Comm_size(MPI_COMM_WORLD, &size);
int d[] = { 1000, 1000, 1000, 1000, 1000, 1000 };
int vt[6] = { 1000, 1000, 1000, 1000, 1000, 1000 };
int ** p;
p = (int *)malloc(sizeof(int *)* 6);
int i = 0;
int row = 6;
int col = 6;
while (i < 6)
{
p[i] = (int *)malloc(sizeof(int *)* 6);
/*int j = 0;
if (rank == 0)
{
while (j < 6)
{
scanf("%d", p[i][j]);
j++;
}
}*/
i++;
}
p[0][0] = 0; p[0][1] =2 ; p[0][2] =3 ; p[0][3] =1 ; p[0][4] =1000 ; p[0][5] =1000 ;
p[1][0] = 2; p[1][1] = 0; p[1][2] = 1000; p[1][3] = 1000; p[1][4] = 5; p[1][5] = 1000;
p[2][0] = 3; p[2][1] = 1000; p[2][2] = 0; p[2][3] = 1000; p[2][4] = 1000; p[2][5] = 1;
p[3][0] = 1; p[3][1] = 1000; p[3][2] = 1000; p[3][3] = 0; p[3][4] = 4; p[3][5] = 3;
p[4][0] = 1000; p[4][1] = 5; p[4][2] = 1000; p[4][3] = 4; p[4][4] = 0; p[4][5] = 2;
p[5][0] = 1000; p[5][1] = 1000; p[5][2] = 1; p[5][3] = 3; p[5][4] = 2; p[5][5] = 0;
int smallest;
if (rank == 0)
{
//transpose(&p , row , col);
smallest = 0;
vt[smallest] = smallest;
//MPI_Bcast();
}
int vt1, d1;
vt1 = d1 = 0;
int roww[6];
MPI_Scatter(vt, 6, MPI_INT, vt1, 1, MPI_INT, 0, MPI_COMM_WORLD);
MPI_Scatter(d, 6, MPI_INT, d1, 1, MPI_INT, 0, MPI_COMM_WORLD);
MPI_Scatter(p, row *row, MPI_INT,roww, 6, MPI_INT, 0, MPI_COMM_WORLD);
i = 0;
while (i < (row*row)/size)
{
MPI_Bcast(smallest, 1, MPI_INT, 0, MPI_COMM_WORLD);
if (vt1 != rank)
{
if (roww[smallest] != 1000)
{
if (d1 > roww[smallest])
d1 = roww[smallest];
}
}
MPI_Gather(d1, 1, MPI_INT, d, row, MPI_INT, 0, MPI_COMM_WORLD);
if (rank == 0)
{
smallest = d[0];
int k = 1;
int index = 0;
while (k < 6)
{
if (d[k] < smallest)
{
smallest = d[k];
index = k;
}
k++;
}
vt[k] = index;
}
MPI_Scatter(vt, 6, MPI_INT, vt1, (row) / size, MPI_INT, 0, MPI_COMM_WORLD);
MPI_Scatter(d, 6, MPI_INT, d1, (row) / size, MPI_INT, 0, MPI_COMM_WORLD);
i++;
}
MPI_Finalize();
}
我得到的错误是
致命错误：MPI_Scatter中的致命错误：无效的缓冲区指针，错误堆栈：
MPI_Scatter（760）：MPI_Scatter（sbuf = 0x0085f7ac，scount，MPI_INT，rbuf = 0x0000000，rcount = 1，MPI_INT，root = 0，MPI_COMM_WORLD）失败
答案 0 :(得分：0)
您提供的代码会编译许多不容忽视的警告，例如：
passing argument 2 of ‘MPI_Init’ from incompatible pointer type
仔细查看函数原型：如果调用类似int* fun(int* b);的内容，int d;fun(d);可能会失败。如果函数需要指向数据的指针，fun(&d)可能会更好。出现此问题很多次，因为调用了MPI函数。
更多：功能transpose(int ** p)尝试通过p修改p= tempVar。正如@WhozCraig所做的那样，通过int **p;...;transpose(p,...)，transpose()函数范围内的p的副本被修改，但不是p。因此，此函数的正确原型是transpose(int ***p,...)，调用它的正确方法是int** p;...;transpose(&p,...);
关于内存分配：你找到了一种分配2D数组的方法！但是数据在内存中是不连续的，因为每次分配一个行。如果您打算使用MPI_Scatter()等MPI功能，allocating a contiguous 2D array是正确的方法（more）。
其他建议：在正确的时间调用free()以释放内存并避免内存泄漏。 Do not cast the return of malloc()
这是一段应该与mpicc main.c -o main -Wall很好地编译的代码。选项-Wall启用所有警告。它似乎运行正常，但我没有检查结果是否正确。
#include<stdio.h>
#include<mpi.h>
#include<stdlib.h>
void transpose(int *** p, int row, int col)
{
int ** tempVar;
tempVar = malloc(sizeof(int *)* row);
if (tempVar==NULL){printf("malloc failed\n"); exit (1);}
tempVar[0] = malloc(sizeof (int )* col*row);
if (tempVar[0]==NULL){printf("malloc failed\n"); exit (1);}
int i = 0;
for (i=0; i < row; i++)
{
tempVar[i] = &tempVar[0][col*i];
int j = 0;
while (j < col)
{
tempVar[i][j] = (*p)[j][i];
j++;
}
}
free((*p)[0]);
free(*p);
*p = tempVar;
}
int main(int argc, char * argv[])
{
int rank, size;
MPI_Init(&argc, &argv);
MPI_Comm_rank(MPI_COMM_WORLD, &rank);
MPI_Comm_size(MPI_COMM_WORLD, &size);
int d[] = { 1000, 1000, 1000, 1000, 1000, 1000 };
int vt[6] = { 1000, 1000, 1000, 1000, 1000, 1000 };
int ** p;
int i = 0;
int row = 6;
int col = 6;
p = malloc(sizeof(int *)* row);
if (p==NULL){printf("malloc failed\n"); exit (1);}
p[0] = malloc(sizeof(int )* row*col);
if (p[0]==NULL) {printf("malloc failed\n"); exit (1);}
while (i < row)
{
p[i] = &p[0][i*col];
/*int j = 0;
if (rank == 0)
{
while (j < 6)
{
scanf("%d", p[i][j]);
j++;
}
}*/
i++;
}
p[0][0] = 0; p[0][1] =2 ; p[0][2] =3 ; p[0][3] =1 ; p[0][4] =1000 ; p[0][5] =1000 ;
p[1][0] = 2; p[1][1] = 0; p[1][2] = 1000; p[1][3] = 1000; p[1][4] = 5; p[1][5] = 1000;
p[2][0] = 3; p[2][1] = 1000; p[2][2] = 0; p[2][3] = 1000; p[2][4] = 1000; p[2][5] = 1;
p[3][0] = 1; p[3][1] = 1000; p[3][2] = 1000; p[3][3] = 0; p[3][4] = 4; p[3][5] = 3;
p[4][0] = 1000; p[4][1] = 5; p[4][2] = 1000; p[4][3] = 4; p[4][4] = 0; p[4][5] = 2;
p[5][0] = 1000; p[5][1] = 1000; p[5][2] = 1; p[5][3] = 3; p[5][4] = 2; p[5][5] = 0;
int smallest;
if (rank == 0)
{
//transpose(&p , row , col);
smallest = 0;
vt[smallest] = smallest;
//MPI_Bcast();
}
int vt1, d1;
vt1 = d1 = 0;
int roww[col];
MPI_Scatter(vt, 1, MPI_INT, &vt1, 1, MPI_INT, 0, MPI_COMM_WORLD);
MPI_Scatter(d, 1, MPI_INT, &d1, 1, MPI_INT, 0, MPI_COMM_WORLD);
MPI_Scatter(&p[0][0], col, MPI_INT,roww, col, MPI_INT, 0, MPI_COMM_WORLD);
i = 0;
while (i < (row*row)/size)
{
MPI_Bcast(&smallest, 1, MPI_INT, 0, MPI_COMM_WORLD);
if (vt1 != rank)
{
if (roww[smallest] != 1000)
{
if (d1 > roww[smallest])
d1 = roww[smallest];
}
}
MPI_Gather(&d1, 1, MPI_INT, d, 1, MPI_INT, 0, MPI_COMM_WORLD);
if (rank == 0)
{
smallest = d[0];
int k = 1;
int index = 0;
while (k < 6)
{
if (d[k] < smallest)
{
smallest = d[k];
index = k;
}
k++;
}
vt[k] = index;
}
MPI_Scatter(vt, 1, MPI_INT, &vt1, 1, MPI_INT, 0, MPI_COMM_WORLD);
MPI_Scatter(d, 1, MPI_INT, &d1, 1, MPI_INT, 0, MPI_COMM_WORLD);
i++;
}
free(p[0]);
free(p);
MPI_Finalize();
return 0;
}