线程是否可能在C中创建但不调用目标函数？ [英] Is it possible that a thread gets created in C but does not invoke the target function?

问题描述

大家好，



我正在使用C中的线程，我编写了一个代码来创建执行函数的线程。问题是我正在创建线程，但是，目标函数没有被调用。我怎么知道的？我到处都有打印声明。我获得了成功的次数，因为我想要线程，但没有任何目标函数打印语句被打印，我觉得这是奇怪的。



以下是我的代码



<<线程创建>>

Hi all,

I am working with threads in C, I have written a code to create threads which execute a function. Problem is I am getting the threads created, however, the target function is not getting invoked. How do I know it? I have print statements everywhere. I get success as many times as I want the threads but none of the target function print statements are getting printed, which I feel is bizarre.

Below is my code

<<creation of threads>>

void replace(char **args)
{



  char *word1=args[1];
  char *word2=args[2];
  int worker=atoi(args[3]);
  int err;
 // printf("no of workers %d\n",worker);
    int size=0;
      size_t segment;

          int i=0;
            int j;
              //int count=0;
                char *w_ptr;

                         for(i=0;i<worker;i++)
                          {


  int begin = i / (float)worker * filestat.st_size;
  int end   = ( i + 1 )/ (float)worker * filestat.st_size;
   //printf("Searching from %d to %d\n", begin, end );
   thread_data_replace_array[i].begin=begin;
   thread_data_replace_array[i].end=end;
   thread_data_replace_array[i].word1=word1;
   thread_data_replace_array[i].word2=word2;

  //struct thread_data_replace *my_data;
 struct thread_data_replace *my_data=malloc(sizeof(struct thread_data_replace));
   err=pthread_create(&(tid[i]),NULL,s_replace,(void *) &thread_data_replace_array[i]);
    if (err!=0) printf("\n cant create a thread");
     else printf("\n success");
   }

  }

<<>>





<<目标函数>>

<<>>


<<Target function>>

void *s_replace(void *threadarg)
{
 // int count=0;
  pthread_mutex_lock(&relock);
 printf("\ninside s_replace for a new thread");

  //  struct thread_data_replace *my_data;
 // my_data=malloc(sizeof(struct(thread_data_replace)));
  struct thread_data_replace *my_data=(struct thread_data_replace *)threadarg;

   int begin=my_data->begin;
    int end= my_data->end;
    char *word1= my_data->word1;
   char *word2= my_data->word2;

    int j;
    int i;
    printf("\ninside replace word to be replaced is %s",word1);
    printf("\n inside replace replaced word is %s",word2);
    printf("\n from %d to %d in replace",begin, end);
     for(j=begin;j<end;j++)>
     {
      //printf("\n inside for not inside if replacing \n");
      if(!memcmp(data+j,word1,strlen(word1)))
      {
        printf("inside if this time for replace function replacing words");
          for(i=j;i<strlen(word1);i++)>
          {
           data[i]=word2[i];
          }
      }
      }

    pthread_mutex_unlock(&relock);

 }

<<>>



我尝试过：



我在创建线程而不是在目标函数中尝试将内存分配给参数结构。我到处都有锁，所以我不会有不稳定的行为。如果它有帮助，在ssh的帮助下在unix机器上工作。



当我输入6个线程作为输入时我得到的输出是



成功

成功

成功

成功

成功

成功



然后程序结束

<<>>

What I have tried:

I have tried allocating the memory to the struct of arguments while creating the threads instead of in the target function. I have applied locks everywhere so I don't get erratic behavior. If it helps, m working on a unix machine with the help of an ssh.

the output I get when I give 6 threads as input is

success
success
success
success
success
success

and then the program ends

推荐答案

你没有显示你的调用 replace（）的主函数。因为你的程序终止，你可能不会等待线程终止（完成他们的工作）。换句话说：主线程到达它的结束并在工作线程有机会被执行之前终止。



为了避免这种情况，请调用 pthread_join [ main（）末尾的所有线程，target =_ blanktitle =New Window> ^ ] 函数。这将暂停执行主线程，直到已连接的工作线程终止。

You did not show your main function which calls replace(). Because your programs terminates, you are probably not waiting for the threads to have terminated (done their job). In other words: The main thread reaches it's end and terminates before the worker threads had a chance to be executed.

To avoid this, call pthread_join[^] for all threads at the end of your main() function. This will suspend execution of the main thread until the joined worker threads had terminated.

这篇关于线程是否可能在C中创建但不调用目标函数？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！