使用MPI_Finalize()后的分段错误

Question

我使用openMPI在c编程.我的代码发布在下面.发生的事情是每次运行此程序时都会收到分段错误错误.我相信我已经通过使用这些printf语句来解决问题.分段似乎发生在MPI_Finalize()之后.任何帮助是极大的赞赏.

我收到的错误是:

[linuxscc003:10019] *** Process received signal ***
[linuxscc003:10019] Signal: Segmentation fault (11)
[linuxscc003:10019] Signal code: Address not mapped (1)

和我的代码:

#include <stdio.h>
#include <stdlib.h>
#include <mpi.h> 

int main(int argc, char** argv) 
{
    int i = 0; //index
    int comm_sz, my_rank;
    int part_sum = 0;
    //size of the array is hard-coded in, 

    MPI_Init(NULL,NULL);
    MPI_Comm_size(MPI_COMM_WORLD, &comm_sz);
    MPI_Comm_rank(MPI_COMM_WORLD, &my_rank);

    if(my_rank == 0)
    {
        int* array;
        //generate the array of n elements
        printf("There are %d array elements\n", comm_sz);
        array = (int*)malloc(sizeof(int*)*comm_sz);
        for(i = 0; i < comm_sz; i++)
        {
            //we don't want to count zero in here
            //nobody likes zero
            array[i] = (i+1); 
        }
        for(i = 1; i < comm_sz; i++)
        {
            MPI_Send(&array[i], sizeof(int*), MPI_INT, i, 0, MPI_COMM_WORLD);
        }   
        //part_sum = 1;
        free(array);
        printf("freed array!\n");
    }

    if(my_rank != 0)
    {
        MPI_Recv(&part_sum, sizeof(int*), MPI_INT, 0, 0, MPI_COMM_WORLD, MPI_STATUS_IGNORE);
        printf("proc %d out of %d, I have received %d!\n", my_rank, comm_sz, part_sum);

    }



    printf("proc %d signing off!\n",my_rank);
    MPI_Finalize();
    printf("proc %d signed off!\n",my_rank);
    return 0;
} 

Answer 1

在这一行:

array = (int*)malloc(sizeof(int*)*comm_sz);

sizeof(int*)应该是sizeof(int).

在这一行:

MPI_Send(&array[i], sizeof(int*), MPI_INT, i, 0, MPI_COMM_WORLD);

sizeof(int*)应该是1.您指定MPI_INT要发送多少s(而不是多少字节). sizeof(int)可能是4或8,所以你正在重读你的缓冲区.

在这一行:

MPI_Recv(&part_sum, sizeof(int*), MPI_INT, 0, 0, MPI_COMM_WORLD, MPI_STATUS_IGNORE);

sizeof(int*) 应该是1,同样的事情.

段错误可能MPI_Finalize()在某个进程之前发生,您认为它发生在其他进程已完成之后MPI_Finalize().或者有可能因为你part_sum在堆栈上覆盖了被破坏的堆栈,直到MPI_Finalize()被调用才会导致问题.