从pthread运行pthreads

Question

我有一个文件，其中包含一个文件名列表，其中我想要搜索一个词并替换它 我修改了一些代码，仅仅显示相关部分 问题是如果我有只有一个文件在该列表中，它不会用多线程处理它，因为线程只在我有多个文件时才工作 所以我想保留当前的线程配置，但我想在处理部分添加一些线程 我有验证码：

struct words_list { 
    char word[20]; 
    struct words_list * next; 
}; 
FILE * INFILE; 
int num_thread = 10; 
// Mutex variables 
pthread_mutex_t input_queue; 
pthread_mutex_t word_list; 


int main(int argc,char **argv) 
{ 
    //some code is missing 

    if((INFILE = fopen(myfile,"r")) == NULL) { 
     fprintf(stderr,"Can't open input file\n"); 
     exit(0); 
    } 

    for(i = 0 ; i < number_thread; i++) 
    { 
     if(pthread_create(&thread_id[i],NULL,&search,NULL) != 0) 
     { 
      i--; 
      fprintf(stderr,RED "\nError in creating thread\n" NONE); 
     } 
    } 
    for(i = 0 ; i < number_thread; i++) 
     if(pthread_join(thread_id[i],NULL) != 0) 
     { 
      fprintf(stderr,RED "\nError in joining thread\n" NONE); 
     } 

    fflush(INFILE); 
    fclose(INFILE); 
} 

void * search(void * data) 
{ 
    char file[20]; 
    while (!feof(INFILE)) 
    { 
     if (fgets(file,sizeof(file),INFILE) != NULL) 
     { 
      if (strlen(file) < 8) 
       break; 
      if (file[strlen (file) - 1] == '\n') 
       file[strlen (file) - 1] = '\0'; 
     } 
     process(file); 
    } 
    return NULL; 
} 


void process(char *filename) 
{ 
    char buff[512]; 
    char word[20]; 
    struct words_list * curr_word = first_word; 

    if(verbose != 0) 
     fprintf(stderr,"Processing: %s\n",filename); 
    while(curr_word != NULL) 
    { 
     //some code missing 
     pthread_mutex_lock(&word_list); 
     strncpy(word,curr_word->word,sizeof(word) - 1); 
     pthread_mutex_unlock(&word_list); 


      **//replace_word must run with multiple threads** 

     ret = replace_word(word,buff,sizeof(buff)); 

      //end of threads part 



     //code missing 
    } 
} 

我怎样才能在加粗部分添加其他并行线程所以它可以用多个线程处理每个文件？

Answer 1

而不是为每个文件分配一个线程。为什么你不应该分配一个线程来处理每个文件的部分。如下所示，我为文件中的每50个字节的数据分配一个线程。在这种技术中，即使列表中只有一个文件，仍然可以使用多个线程来解析它。希望能帮助到你。

#include "stdio.h" 
#include "pthread.h" 
#include "sys/stat.h" 
#include "string.h" 
#include "fcntl.h" 

#define TOTAL_NUMBER_THREADS 100 

struct words_list { 
    char word[20]; 
    struct words_list * next; 
}; 

struct file_segment { 
    char filename[50]; 
    size_t foffset; 
    size_t size; 
}fs[TOTAL_NUMBER_THREADS]; 

FILE * INFILE; 
int num_thread=0; 

// Mutex variables 
pthread_mutex_t input_queue; 
pthread_mutex_t word_list; 
pthread_t thread_id[TOTAL_NUMBER_THREADS]; 

void *process(void *arg); 

void segment_file(char *filename) 
{ 
    int fd; 
    int offset=0; 
    struct stat statbuf; 
    size_t size; 

    fd = open(filename, O_RDONLY); 
    if(fd < 0) 
    { 
     perror("fopen"); 
     return; 
    } 

    fstat(fd, &statbuf); 
    size=statbuf.st_size; 

    while((offset < size) && (num_thread <= 100)) 
    { 
     strncpy(fs[num_thread].filename, filename, sizeof(fs[num_thread].filename)); 
     fs[num_thread].foffset=offset; 
     fs[num_thread].size=(size>50)?50:size; 
     offset+=fs[num_thread].size; 

     if(pthread_create(&thread_id[num_thread],NULL,&process,&fs[num_thread]) != 0) 
     { 
     fprintf(stderr,"\nError in creating thread\n"); 
     } 
     num_thread++; 
    } 

    return; 
} 

void *process(void *arg) 
{ 
    char buf[50]; 
    struct file_segment *fs; 
    char word[20]; 
    //struct words_list * curr_word = first_word; 
    fs = (struct file_segment *) arg; 
    FILE *fp; 

    fp=fopen(fs->filename, "r"); 
    fseek(fp, fs->foffset, SEEK_SET); 
    fread(buf,1,fs->size,fp); 

    while(curr_word != NULL) 
    { 
     //some code missing 
     pthread_mutex_lock(&word_list); 
     strncpy(word,curr_word->word,sizeof(word) - 1); 
     pthread_mutex_unlock(&word_list); 


      **//replace_word must run with multiple threads** 

     ret = replace_word(word,buff,sizeof(buff)); 

      //end of threads part 
     //code missing 
    } 

    //printf("Filename: %s\n Info: %s\n", fs->filename, buf); 
    printf("%s", buf); 

    return; 
} 

int main(int argc,char **argv) 
{ 
    //some code is missing 
    char file[50]; 
    int i; 

    if((INFILE = fopen("list.txt","r")) == NULL) { 
     fprintf(stderr,"Can't open input file\n"); 
     return 0; } 

    while (!feof(INFILE)) 
    { 
     if (fgets(file,sizeof(file),INFILE) != NULL) 
     { 
      if (strlen(file) < 8) 
       break; 
      if (file[strlen (file) - 1] == '\n') 
       file[strlen (file) - 1] = '\0'; 
     } 
     segment_file(file); 
    } 

    for(i = 0 ; i < num_thread; i++) 
     if(pthread_join(thread_id[i],NULL) != 0) 
     { 
      fprintf(stderr,"\nError in joining thread\n"); 
     } 

    fflush(INFILE); 
    fclose(INFILE); 
}