pthreads is running out of threads

[Elmi]

Hi,

I have a problem that after some time pthreads is no longer able to create new threads. The funny thing is, I do not create too much threads at the same time but threads out of threads. What I do is the following:

1. create a thread
2. within this thread I wait some milliseconds
3. now I do some work which takes some time
4. out of this thread I start with 1.
5. as soon as the new thread was created successfully I clean up the current thread and exit it

So as far as I understand it the previous thread should have been gone long time before I could run out of threads because the total number of threads that runs at the same time is exceeded. Unfortunately this is not what I notice: after about 40..50 thread creations pthread_create() fails with EAGAIN.

So what could be the reason for that? Thread-creation is done quite simple:

   pthread_t *thread;
   int        ret;

   thread=(pthread_t*)malloc(sizeof(pthread_t));
   if (!thread) return NULL;

   ret=pthread_create(thread,NULL,start_routine,arg);

[Rubberman]

Do you call pthread_exit()? Does the creating thread call pthread_join()? If you don't do this, the resources are still used up. The pthread_exit() call will terminate the thread, and pthread_join() called by the creating, or other thread, will merge their resources so that you won't run into this situation.

[mstabie]

I think if you call pthread_detach it will fix your problem. Without it, or setting the detach state attribute using pthread_attr_init, the resource will wait for a pthread_join.