PTHREAD_JOIN

pthread_join ? wait for termination of another thread

#include <pthread.h>

int pthread_join(pthread_t th, void **thread_return);

pthread_join suspends the execution of the calling thread until the thread identified by th terminates, either by calling pthread_exit(3) or by being cancelled.

If thread_return is not NULL, the return value of th is stored in the location pointed to by thread_return. The return value of th is either the argument it gave to pthread_exit(3), or PTHREAD_CANCELED if th was cancelled.

The joined thread th must be in the joinable state: it must not have been detached using pthread_detach(3) or the PTHREAD_CREATE_DETACHED attribute to pthread_create(3).

When a joinable thread terminates, its memory resources (thread descriptor and stack) are not deallocated until another thread performs pthread_join on it. Therefore, pthread_join must be called once for each joinable thread created to avoid memory leaks.

At most one thread can wait for the termination of a given thread. Calling pthread_join on a thread th on which another thread is already waiting for termination returns an error.

pthread_join is a cancellation point. If a thread is canceled while suspended in pthread_join, the thread execution resumes immediately and the cancellation is executed without waiting for the th thread to terminate. If cancellation occurs during pthread_join, the th thread remains not joined.

On success, the return value of th is stored in the location pointed to by thread_return, and 0 is returned. On error, a non-zero error code is returned.

ESRCH

No thread could be found corresponding to that specified by th.

EINVAL

The th thread has been detached.

EINVAL

Another thread is already waiting on termination of th.

EDEADLK

The th argument refers to the calling thread.

Xavier Leroy <Xavier.Leroy@inria.fr>

pthread_exit(3), pthread_detach(3), pthread_create(3), pthread_attr_setdetachstate(3), pthread_cleanup_push(3), pthread_key_create(3).