捕获信号 11（分段错误：地址未映射到地址 (nil) 处的对象

Question

我正在尝试使用reduce命令计算数组A的总和；请注意，A 仅对主节点/根 (0) 可见。

我收到以下错误，但我似乎无法弄清楚为什么。此外，广播部分 (N) 仍然会产生相同的错误。

错误：

[kali:74924:0:74924] Caught signal 11 (Segmentation fault: address not mapped to object at address (nil))
==== backtrace (tid:  74924) ====
 0  /lib/x86_64-linux-gnu/libucs.so.0(ucs_handle_error+0x2dc) [0x7f14b5486a9c]
 1  /lib/x86_64-linux-gnu/libucs.so.0(+0x28c8f) [0x7f14b5486c8f]
 2  /lib/x86_64-linux-gnu/libucs.so.0(+0x28e4a) [0x7f14b5486e4a]
 3  /lib/x86_64-linux-gnu/libc.so.6(+0x3c910) [0x7f14b564e910]
 4  ./parts(+0x14f1) [0x557de43984f1]
 5  /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xcd) [0x7f14b56397ed]
 6  ./parts(+0x113a) [0x557de439813a]
=================================
[kali:74925:0:74925] Caught signal 11 (Segmentation fault: address not mapped to object at address (nil))
==== backtrace (tid:  74925) ====
 0  /lib/x86_64-linux-gnu/libucs.so.0(ucs_handle_error+0x2dc) [0x7fb3324b0a9c]
 1  /lib/x86_64-linux-gnu/libucs.so.0(+0x28c8f) [0x7fb3324b0c8f]
 2  /lib/x86_64-linux-gnu/libucs.so.0(+0x28e4a) [0x7fb3324b0e4a]
 3  /lib/x86_64-linux-gnu/libc.so.6(+0x3c910) [0x7fb332678910]
 4  ./parts(+0x14f1) [0x5581e42d44f1]
 5  /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xcd) [0x7fb3326637ed]
 6  ./parts(+0x113a) [0x5581e42d413a]
=================================
[kali:74926:0:74926] Caught signal 11 (Segmentation fault: address not mapped to object at address (nil))
==== backtrace (tid:  74926) ====
 0  /lib/x86_64-linux-gnu/libucs.so.0(ucs_handle_error+0x2dc) [0x7f7e8e8f9a9c]
 1  /lib/x86_64-linux-gnu/libucs.so.0(+0x28c8f) [0x7f7e8e8f9c8f]
 2  /lib/x86_64-linux-gnu/libucs.so.0(+0x28e4a) [0x7f7e8e8f9e4a]
 3  /lib/x86_64-linux-gnu/libc.so.6(+0x3c910) [0x7f7e8eac1910]
 4  ./parts(+0x14f1) [0x558b09e094f1]
 5  /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xcd) [0x7f7e8eaac7ed]
 6  ./parts(+0x113a) [0x558b09e0913a]
=================================

===================================================================================
=   BAD TERMINATION OF ONE OF YOUR APPLICATION PROCESSES
=   PID 74924 RUNNING AT kali
=   EXIT CODE: 11
=   CLEANING UP REMAINING PROCESSES
=   YOU CAN IGNORE THE BELOW CLEANUP MESSAGES
===================================================================================
YOUR APPLICATION TERMINATED WITH THE EXIT STRING: Segmentation fault (signal 11)
This typically refers to a problem with your application.
Please see the FAQ page for debugging suggestions

代码：

不带广播

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

int main (int argc, char** argv) {
    int rank;
    int size;
    int sum = 0;
    int grand_sum = 0;
    int i;
    int *A;
    int N;
    int part;

    MPI_Init(&argc, &argv);
    MPI_Comm_rank(MPI_COMM_WORLD, &rank);
    MPI_Comm_size(MPI_COMM_WORLD, &size);

    if (rank == 0) {
        do {
            printf("Enter the array size: ");
            scanf("%d", &N);
        } while (N <= 0);

        A = malloc(N * sizeof(int));
        if (!A) {
            printf("Array too big!\nExiting the program...\n");
            return -1;
        }

        part = N / size;

        srand(10);
        for (i = 0; i < N; i++) {
            A[i] = rand() % 10 + 1;
            grand_sum += A[i];
            printf("A[%d] = %d\n", i, A[i]);
        }
        
        for (i = 1; i < size; i++) {
            MPI_Send(&part, 1, MPI_INT, i, 0, MPI_COMM_WORLD);
            MPI_Send(&A[i * part], part, MPI_INT, i, 0, MPI_COMM_WORLD);
        }
    } else {
        int part;
        MPI_Recv(&part, 1, MPI_INT, 0, 0, MPI_COMM_WORLD, MPI_STATUS_IGNORE);
        int Aw[part];
        MPI_Recv(&Aw, part, MPI_INT, 0, 0, MPI_COMM_WORLD, MPI_STATUS_IGNORE);

        for (i = 0; i < part; i++) {
            sum += A[i];
        }
    }

    MPI_Reduce(&sum, &grand_sum, 1, MPI_INT, MPI_SUM, 0, MPI_COMM_WORLD);

    if (rank == 0) {
        for (i = size * part; i < N; i++) {
            grand_sum += A[i];
        }

        printf("\nThe grand sum is: %d", grand_sum);
    }

    MPI_Finalize();
}

带广播

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

int main (int argc, char** argv) {
    int rank;
    int size;
    int sum = 0;
    int grand_sum = 0;
    int i;
    int *A;
    int N;
    int part;

    MPI_Init(&argc, &argv);
    MPI_Comm_rank(MPI_COMM_WORLD, &rank);
    MPI_Comm_size(MPI_COMM_WORLD, &size);

    if (rank == 0) {
        do {
            printf("Enter the array size: ");
            scanf("%d", &N);
        } while (N <= 0);

        A = malloc(N * sizeof(int));
        if (!A) {
            printf("Array too big!\nExiting the program...\n");
            return -1;
        }

        part = N / size;

        srand(10);
        for (i = 0; i < N; i++) {
            A[i] = rand() % 10 + 1;
            printf("A[%d] = %d\n", i, A[i]);
        }
        
        for (i = 1; i < size; i++) {
            //MPI_Send(&part, 1, MPI_INT, i, 0, MPI_COMM_WORLD);
            MPI_Send(&A[i * part], part, MPI_INT, i, 0, MPI_COMM_WORLD);
        }
    } 
    
    MPI_Bcast(&part, 1, MPI_INT, 0, MPI_COMM_WORLD);

    if (rank != 0) {
        //MPI_Recv(&part, 1, MPI_INT, 0, 0, MPI_COMM_WORLD, MPI_STATUS_IGNORE);
        int Aw[part];
        MPI_Recv(&Aw, part, MPI_INT, 0, 0, MPI_COMM_WORLD, MPI_STATUS_IGNORE);

        for (i = 0; i < part; i++) {
            sum += A[i];
        }
    }

    MPI_Reduce(&sum, &grand_sum, 1, MPI_INT, MPI_SUM, 0, MPI_COMM_WORLD);

    if (rank == 0) {
        for (i = size * part; i < N; i++) {
            grand_sum += A[i];
        }

        printf("\nThe grand sum is: %d", grand_sum);
    }

    MPI_Finalize();
}

Answer 1

重新阅读我的代码后，我在 else 语句的 for 循环中发现了一个错误：

for (i = 0; i < part; i++) {
            sum += A[i];
}

A 在这里不可见；因此出现错误。这里应该使用Aw。

正确代码：

for (i = 0; i < part; i++) {
            sum += Aw[i];
}