C:信号代码:未映射的地址(1)mpirecv

Question

我用C语言用MPI编写了以下代码:

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

int main(int argc, char *argv[])
{
    int size, rank;
    MPI_Status status;
    int buf[1000];

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

    if (rank == 0) {
        int i = 0;

        while (i != 1000) {
            buf[i] = i;
            i++;
        }

        MPI_Send(buf, 999, MPI_INT, 1, 1, MPI_COMM_WORLD);
        printf("msg has been sent\n");
    }

    if (rank == 1) {
        int sz = sizeof(buf);
        int lst = buf[sz-1];

        MPI_Recv(buf, 999, MPI_INT, 0, 1, MPI_COMM_WORLD, &status);
        printf("la taille du buf %d et dernier %d", sz, lst);
    }

    MPI_Finalize();
}

运行后它会给出这样的信息:

msg has been sente
[blitzkrieg-TravelMate-P253:03395] *** Process received signal ***
[blitzkrieg-TravelMate-P253:03395] Signal: Segmentation fault (11)
[blitzkrieg-TravelMate-P253:03395] Signal code: Address not mapped (1)
[blitzkrieg-TravelMate-P253:03395] Failing at address: 0xbfee8574
[blitzkrieg-TravelMate-P253:03395] [0] [0xb772d40c]
[blitzkrieg-TravelMate-P253:03395] [1] mpii(main+0x12f) [0x8048883]
[blitzkrieg-TravelMate-P253:03395] [2] /lib/i386-linux-gnu/libc.so.6(__libc_start_main+0xf3) [0xb74c84d3]
[blitzkrieg-TravelMate-P253:03395] [3] mpii() [0x80486c1]
[blitzkrieg-TravelMate-P253:03395] *** End of error message ***

---

mpirun注意到节点闪电战上的进程等级1和PID 3395-

TravelMate-P253退出信号11(分段故障).

任何建议都将有助于thnx.

Answer 1

堆栈跟踪显示错误不在MPI_Recv问题标题中.错误实际上在这里:

int sz = sizeof(buf);
int lst = buf[sz-1]; // <---- here

由于buf是一个数组int并sizeof(buf)以字节sz为单位返回其大小,因此设置为数组中元素数的4倍.访问buf[sz-1]超出buf了进程堆栈上方的未映射内存区域的范围.

您应该将数组的总大小除以其中一个元素的大小,例如第一个:

int sz = sizeof(buf) / sizeof(buf[0]);
int lst = buf[sz-1];