随机段错误当使用全局二维变量而不是局部变量时

Question

这是完成了一半的代码，我应该将其转换为多线程代码。
我需要在所有线程中读取全局二维双变量“vector”。
所以我将它从 main 中的本地 var 转换为全局变量（如你所见，我在第 33 行评论了旧的）突然在仅此一次更改之后我的代码开始提供运行dom 但经常出现段错误我将其改回到本地和运行代码 1000 次而不是一次崩溃，但是将这个本地 2d var 更改为全局将破坏一切
我真的不知道该怎么办，请帮助我。

# include <stdio.h> 
# include <string.h> 
# include <pthread.h>
# include <stdlib.h>
# include <math.h>

# define NUMBER_OF_COLUMNS 20
# define NUMBER_OF_CLASSES 4
# define NUMBER_OF_THREADS 4
# define NUMBER_OF_COLUMNS_PLUS_ONE 21 //STUPID C WONT LET ME MAKE GLOBAL VECTORS
    double vectors[NUMBER_OF_CLASSES][NUMBER_OF_COLUMNS_PLUS_ONE];

double max[NUMBER_OF_COLUMNS], min[NUMBER_OF_COLUMNS];
pthread_t threads[NUMBER_OF_THREADS];
void * solve(void *id){
    FILE *traincsv;
    long tid;
    tid = (long) id;
    char buffer[1024];
    char* token;
    int EOFchecker = 1;
    printf("Hello World! Thread ID, %ld\n", tid);
    pthread_exit(NULL);
}
int main(){
    FILE *traincsv, *traincsvnorm, *weightscsv;
    char buffer[1024];
    char* token;
    double temp;
    // double max[NUMBER_OF_COLUMNS], min[NUMBER_OF_COLUMNS];
    int EOFchecker = 1;
    int number_of_datas = 0, number_of_wrong_predictions = 0;
    // double vectors[NUMBER_OF_CLASSES][NUMBER_OF_COLUMNS + 1];
    double sum[NUMBER_OF_CLASSES];
    int winner;
    int return_code;
    for (size_t i = 0; i < NUMBER_OF_COLUMNS; i++)
    {
        min[i] = INFINITY;
    }
    
    
    traincsv = fopen("train.csv","r");
    traincsvnorm = fopen("trainnorm.csv","w+");
    weightscsv = fopen("weights.csv","r");
    // fprintf(traincsvnorm,"%s\n",buffer);
    //load vectors to array last one is bias
    fscanf(weightscsv,"%s",buffer);//first junk line
    for (size_t i = 0; i < NUMBER_OF_CLASSES; i++)
    {
        fscanf(weightscsv,"%s",buffer);
        token = strtok(buffer,",");
        for (size_t j = 0; j < NUMBER_OF_COLUMNS + 1; j++)
        {
            temp = atof(token);
            vectors[i][j] = temp;
            token = strtok(NULL,",");//next token of last string
        }
    }
    //find min and max
    fscanf(traincsv,"%s",buffer);//first line is just names
    fscanf(traincsv,"%s",buffer);
    while (EOFchecker != EOF)
    {
        token = strtok(buffer,",");
        for (size_t i = 0; i < NUMBER_OF_COLUMNS; i++)
        {
            temp = atof(token);
            if(max[i]<temp) max[i] = temp;
            if(min[i]>temp) min[i] = temp;
            token = strtok(NULL,",");//next token of last string
        }
        EOFchecker = fscanf(traincsv,"%s",buffer);
    }
    // Normilize
    double maxMinusMin[NUMBER_OF_COLUMNS];
    for (size_t i = 0; i < NUMBER_OF_COLUMNS; i++)
    {
        maxMinusMin[i] = max[i] - min[i];
    }
    EOFchecker = 1;
    fseek(traincsv,0,SEEK_SET);
    fscanf(traincsv,"%s",buffer);//first line is just names
    fscanf(traincsv,"%s",buffer);
    while (EOFchecker != EOF)
    {
        token = strtok(buffer,",");
        //reset sum of wieghts to bias;
        for (size_t i = 0; i < NUMBER_OF_CLASSES; i++)
        {
            sum[i] = vectors[i][NUMBER_OF_COLUMNS];
        }
        for (size_t i = 0; i < NUMBER_OF_COLUMNS; i++)
        {
            temp = atof(token);
            temp = (temp-min[i])/(maxMinusMin[i]);
            for (size_t j = 0; j < NUMBER_OF_CLASSES; j++)
            {
                sum[j] += vectors[j][i] * temp;
            }
            token = strtok(NULL,",");//next token of last string
        }
        //check which vector has most points
        for (size_t i = 0; i < NUMBER_OF_CLASSES; i++)
        {
            if (sum[i] > sum[winner])
            {
                winner = i;
            }
            
        }
        if(winner != atof(token)){
            number_of_wrong_predictions ++;
        }
        number_of_datas ++;
        EOFchecker = fscanf(traincsv,"%s",buffer);
    }
    // for(long tid = 0; tid < NUMBER_OF_THREADS; tid++)
    // {
    //     printf("%ld\n",tid);
    //  return_code = pthread_create(&threads[tid],
    //          NULL, solve, (void *) tid);

    //  if (return_code)
    //  {
    //      printf("ERROR; return code from pthread_create() is %d\n",
    //              return_code);
    //      exit(-1);
    //  }
    // }

    printf("wrong predictions : %d \nall predictions : %d \n",number_of_wrong_predictions,number_of_datas);
    fclose(traincsv);
    fclose(traincsvnorm);
    fclose(weightscsv);
    pthread_exit(NULL);
}

这些是输入 train.csv weights.csv

Answer 1

变量winner在第一次使用的时候没有初始化所以，
如果（总和[i]>总和[获胜者]）可能会访问 sum 之外的字段并导致段错误。

当向量数组在堆栈上时，获胜者可能具有较小的随机值并且不会导致段错误。

随机段错误当使用全局二维变量而不是局部变量时

Random segfault When using global 2d variable instead of local one

c

global-variables

segmentation-fault