PTHREAD_JOIN(3C) Standard C Library Functions PTHREAD_JOIN(3C)

NAME

pthread_join - wait for thread termination

SYNOPSIS

cc -mt [ flag... ] file... -lpthread [ library... ]
#include <pthread.h>

int pthread_join(pthread_t thread, void **status);

DESCRIPTION

The pthread_join() function suspends processing of the calling thread
until the target thread completes. thread must be a member of the current
process and it cannot be a detached thread. See pthread_create(3C).


If two or more threads wait for the same thread to complete, all will
suspend processing until the thread has terminated, and then one thread
will return successfully and the others will return with an error of
ESRCH. The pthread_join() function will not block processing of the
calling thread if the target thread has already terminated.


If a pthread_join() call returns successfully with a non-null status
argument, the value passed to pthread_exit(3C) by the terminating thread
will be placed in the location referenced by status.


If the pthread_join() calling thread is cancelled, then the target thread
will remain joinable by pthread_join(). However, the calling thread may
set up a cancellation cleanup handler on thread prior to the join call,
which may detach the target thread by calling pthread_detach(3C). See
pthread_detach(3C) and pthread_cancel(3C).

RETURN VALUES

If successful, pthread_join() returns 0. Otherwise, an error number is
returned to indicate the error.

ERRORS

EDEADLK
A joining deadlock would occur, such as when a thread attempts
to wait for itself.


EINVAL
The thread corresponding to the given thread ID is a detached
thread.


ESRCH
No thread could be found corresponding to the given thread ID.

ATTRIBUTES

See attributes(7) for descriptions of the following attributes:


+--------------------+-----------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-----------------+
|Interface Stability | Standard |
+--------------------+-----------------+
|MT-Level | MT-Safe |
+--------------------+-----------------+

SEE ALSO

pthread_cancel(3C), pthread_create(3C), pthread_detach(3C),
pthread_exit(3C), wait(3C), attributes(7), standards(7)

NOTES

The pthread_join(3C) function must specify the thread ID for whose
termination it will wait.


Calling pthread_join() also "detaches" the thread; that is,
pthread_join() includes the effect of the pthread_detach() function. If a
thread were to be cancelled when blocked in pthread_join(), an explicit
detach would have to be performed in the cancellation cleanup handler.
The pthread_detach() function exists primarily for this purpose.

March 23, 2005 PTHREAD_JOIN(3C)