pthread create and join problems

[rotis23]

i have a daemon process that creates and joins multiple threads.

every so often the pthread error check will fail and the program terminate.

under what conditions would the pthread_create function fail?

i'm really looking for some practical reasons. i believe that the code is correct.

i'm also having problems with pthread_join hanging randomly.

any ideas?

TIA, rotis23

*************************************************

        pthread_exit(NULL);     //end of thread_function

*************************************************

        int res;
        int lots_of_threads;
        int num_sites;
        pthread_t a_thread[5];
        void *thread_result;

        //initialise mutex - used to synchronise linked list between threads
        res = pthread_mutex_init(&queue_mutex, NULL);
        if (res != 0){printf("mutex creation failure.\n");

        //add multiple threads
        for(lots_of_threads = 0; lots_of_threads < 5; lots_of_threads++)
        {
                //threads are created and started
                res = pthread_create(&(a_thread[lots_of_threads]), NULL,
thread_function, (void *)lots_of_threads);
                if (res != 0){printf(&quot;create failure.\n&quot;);
        }

        //wait for threads to finish and clean up
        printf(&quot;Waiting for threads to finish...\n&quot;);

        for(lots_of_threads = 5 - 1; lots_of_threads >= 0;
lots_of_threads--)
        {
                res = pthread_join(a_thread[lots_of_threads], NULL);
                if (res == 0)
                {
                        printf(&quot;Picked up a thread\n&quot;);
                }
                else{printf(&quot;join error.\n&quot;);
        }

 

[xwb]

There is normally some limit on how many threads you can create. If you hit that limit, then pthread_create will not be able to create anymore threads. Instead on creating and joining, you could go for the thread pool idea. This is described in the Nutshell book on pthreads.