Code Correctness: Premature Thread Termination

If a parent process finishes execution normally before the threads it has spawned, the threads can be terminated prematurely.

Threads spawned by calling pthread_create() from the main() function of the parent process will be terminated prematurely if the parent process finishes execution before any the threads it has spawned without calling pthread_exit(). Calling pthread_exit() guarantees that the parent process will be kept alive until all of its threads have finished execution. Alternatively, the parent process can call pthread_join on all of the child threads and ensure they will complete before the process concludes.

Example 1: The following code uses pthread_create() to create a thread and then exits normally. If the child thread has not completed its execution by the time the main() function returns, then it will be terminated prematurely.

void *Simple(void *threadid)
{
   ...
   pthread_exit(NULL);
}

int main(int argc, char *argv[]) {
   int rc;
   pthread_t pt;
   rc = pthread_create(&pt, NULL, Simple, (void *)t);
   if (rc){
     exit(-1);
   }
}