#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <pthread.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <unistd.h>
#include <time.h>

pthread_mutex_t lock;

//typedef struct for a word
typedef struct {
    char word[101];
    int frequency;
}Word;

//struct for thread
struct ft{
    char* fileName;
    int start;
    int stop;
};

//compare frequency of 2 words 
int compareWords(const void *f1,const void *f2){
    Word *a = (Word *)f1;
    Word *b = (Word *)f2;
    return (b->frequency - a->frequency);
}

//count frequency of a word
void countFrequency(void *arg){

    pthread_mutex_lock(&lock);

    int i,c;
    struct ft* fi = (struct ft*)arg;
    FILE *file = fopen(fi->fileName,"r");
    fseek(file,fi->start,SEEK_SET);
    for(i = 0; i < fi->stop - fi->start; i++){
        c = getc(file);
        //printf("%d\n",c);
        //frequency count
    }

    fclose(file);

    pthread_mutex_unlock(&lock);
}

int main (int argc,char **argv){

    //variabies for <time.h>
    struct timespec startTime;
    struct timespec endTime;
    clock_gettime(CLOCK_REALTIME,&startTime);

    /*------------main------------------*/

    //variables
    int nthreads;   //number of threads
    int chunkSize;  //each threas processing size

    //if user input is not correct,inform
    if(argc < 3){ 
       printf("./a.out text_file #ofthreads \n");
       exit(-1);
    }


    nthreads = atoi(argv[2]);
    chunkSize = sizeof(argv[1])/nthreads;

    //declare threads and default attributes
    pthread_t threads[nthreads];
    pthread_attr_t attr;
    pthread_attr_init(&attr);

    //run threads in parallel
    int i; 
    for (i = 0; i < nthreads; i++){
       struct ft data[nthreads];
       data[i].start = i*chunkSize;
       data[i].stop = data[i].start+chunkSize;
       data[i].fileName = argv[1];


       // Create a new thread for every segment,and count word  frequency for each
       pthread_create(&threads[i],&attr,(void*) countFrequency,(void*) &data[i]);

    }

    //wait for results (all threads)
    for (i = 0; i < nthreads; i++){
       pthread_join(threads[i],NULL);
    } 

       //func of <time.h>
       clock_gettime(CLOCK_REALTIME,&endTime);
       time_t sec = endTime.tv_sec - startTime.tv_sec;
       long n_sec = endTime.tv_nsec - startTime.tv_nsec;
       if (endTime.tv_nsec < startTime.tv_nsec)
        {
        --sec;
        n_sec = n_sec + 1000000000L;
        }
       printf("Total Time was %ld.%09ld seconds\n",sec,n_sec);
}

我正在使用该程序来使用多个线程读取和处理大型文本文件，并对文本中长度超过6个字符的前10个最常用单词执行单词计数频率。但是我不知道为什么会不断出现细分错误错误，有人知道吗？