CODEWITHSUNDEEP
cmultithreadingpthreads
user3021085
user3021085

Reputation: 417

re-using threads with the same number pthread

Is it allowed to re-use thread with the same thread number if they have terminated?

I have written a small piece of code which re-uses thread numbers if the threads are no longer busy and have been terminated. Here is the code. It works but I am wondering is if what I am doing is allowed?

It prints out what the thread id, the current position of the main loop and the the current position of the function loop is.

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

#define NUM_THREADS     8
#define NUM_LOOP       17

typedef struct infos {    
   int mainloop;
   int thread_id;
   int *busy;   
} infos;


void *printtest(void *arg){

   int i,sleep;
   infos *infostruct=(infos*)(arg);

   for (i=0;i<5;i++) {
      sleep=rand()%1000000;
      printf("thead_id  %2i | main  %2i | loop: %2i\n",infostruct->thread_id,infostruct->mainloop,i);
      usleep( sleep );
   }

   *infostruct->busy=0;

   pthread_exit(0);

}


int main () {

   pthread_t threads[NUM_THREADS];
   infos     infostruct[NUM_LOOP];

   int       thread_busy[NUM_THREADS]={0},
             thread_found,
             i,j;

   for(i=0;i<NUM_LOOP;i++) {
      thread_found=0;

      while (thread_found!=1) {

         for (j=0;j<NUM_THREADS;j++) {
            /* if non-busy thread is found use its number to create a new thread with that number, link the busy variable with the thread_busy array index of the thread.*/
            if (thread_busy[j]==0) {

               thread_busy[j]=1;
               infostruct[i].thread_id=j;
               infostruct[i].mainloop=i;
               infostruct[i].busy=&thread_busy[j];

               if (pthread_create(&threads[j], NULL, printtest, &infostruct[i])) {
                  printf("ERROR creating thread");
               }

               pthread_detach(threads[j]);
               thread_found=1;

               break;

            }
         }
      } 
   }

   for (i=0;i<NUM_THREADS;i++) {
      while (thread_busy[i]!=0);
   }

   printf("\n!!DONE!!\n");

}

Upvotes: 0

Views: 148

Answers (1)

augurar
augurar

Reputation: 13016

In this code, the "thread number" is entirely your own construct, so you can decide on the rules for how it should be used.

Upvotes: 1

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