标准 C 中的 MPI SEND / RECV 字符串数组

Question

好吧，这几天我一直在为这个问题苦苦挣扎。我正在尝试使用其最新版本的 openmpi 将字符串数组分发到我的 Raspberry Pi 4 计算集群中的各个节点。我认为这是了解聚类如何工作的完美方式，但此时我完全迷失了方向，没有方向。对于当前的代码集，我遇到了分段错误，但是当我按照其他指令集进行操作时，有时我只会收到第一个字符串的第一个字符，并且每隔一个字符为 null。那些时候第一个参数将是 &(NodeOne[0][0]) 而不是当前数组发送行。大多数这些指令集都是 6-9 岁的。有没有人有任何想法让代码做的不仅仅是编译？

#include <stdlib.h>
#include <curl/curl.h>
#include <string.h>
#include <mpi.h>

#define NUMC 4

void *set_Stats(void *z);
struct Tickers {
    char ** x;
    int length;
};
struct Tickers getTickers()
{
    CURL *curl = curl_easy_init();
    char line[300];
    struct Tickers tickers;
    int length = 0;
    char url[60] = "ftp://ftp.nasdaqtrader.com/symboldirectory/nasdaqtraded.txt";
    if(curl)
    {
        FILE *temp = tmpfile();
        curl_easy_setopt(curl, CURLOPT_URL, url);
        curl_easy_setopt(curl, CURLOPT_WRITEDATA, (void*)temp);
        curl_easy_perform(curl);
        if(temp)
        {
            rewind(temp);
            char c = fgetc(temp);
            while (fgets(line,sizeof(line),temp)) 
            {
                length++;
            }
            rewind(temp);
            length = length - 2;
            tickers.length = length;
            tickers.x = malloc(length * sizeof(char*));
            fgets(line, sizeof(line), temp);
            fgets(line, sizeof(line), temp);
            for(int count = 0; count < length; count++)
            {
                char *string = line + 2;
                int tickLen = strstr(string, "|") - string;
                char sub[tickLen]; 
                tickers.x[count] = malloc(tickLen);
                strncpy(sub, string, tickLen);
                sub[tickLen] = '[=10=]';
                strcpy(tickers.x[count], sub);
                fgets(line, sizeof(line), temp);
            }
            fclose(temp);
        }
    }
    curl_easy_cleanup(curl);
    return tickers;
}
char ** allocate_DD(int rows, int cols)
{
    char *data = (char *)malloc(rows*cols);
    char **array= (char **)malloc(rows*sizeof(char*));
    for(int i = 0; i < rows; i++)
        array[i] = &(data[cols*i]);
    return array;
}


int main() //Designed for one master, three slaves
{
    int my_id;
    MPI_Init(NULL,NULL);
    MPI_Comm_rank(MPI_COMM_WORLD, &my_id);
    MPI_Status status;
    int firstNodeLength;
    if(my_id == 0) // meaning this process is a host job
    {
        struct Tickers tickers = getTickers();
        int length = tickers.length / 3;
        int remainder = tickers.length % 3;
        char ** NodeOneTicks = allocate_DD(length + remainder, 6);
        //char ** NodeTwoTicks = allocate_DD(length, 6);
        //char ** NodeThrTicks = allocate_DD(length, 6);
        int count = 0;
        int x = 0;
        while(count < length + remainder)
        {
            strcpy(NodeOneTicks[x], tickers.x[count]);
            NodeOneTicks[x][5] = '[=10=]';
            count++;
            x++;
        }
        x = 0;
        firstNodeLength = length + remainder;
        printf("%d\n", firstNodeLength);
        MPI_Send(&firstNodeLength,1, MPI_INT,1,1000,MPI_COMM_WORLD);
        MPI_Send(NodeOneTicks,firstNodeLength,MPI_CHAR,1,1001,MPI_COMM_WORLD);
        
    }
    else // must be slave process
    {
        int myLen;
        int x = 0;
        
        int ierr = MPI_Recv(&myLen,1,MPI_INT,0,MPI_ANY_TAG,MPI_COMM_WORLD,&status);
        printf("%d\n", myLen);
        char ** myTicks = allocate_DD(myLen,6);
        ierr = MPI_Recv(myTicks[0], myLen,MPI_CHAR,0,MPI_ANY_TAG,MPI_COMM_WORLD,&status);
        myTicks[0][5] = '[=10=]';
        printf("%s\n", myTicks[0]);
    }
    MPI_Finalize();

}

Answer 1

原来问题出在getTickers()返回的原始数组上。尽管当函数是非 mpi 时它打印得很好，但它在某些点溢出，使 MPI 数组成为垃圾。感谢@GillesGouaillardet 帮助/基本上解决了我的问题！

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