NAME

pthread_detach - detach a thread

SYNOPSIS

[THR] #include <pthread.h>

int pthread_detach(pthread_t thread);

DESCRIPTION

The pthread_detach() function shall indicate to the implementation that storage for the thread thread can be reclaimed when that thread terminates. If thread has not terminated, pthread_detach() shall not cause it to terminate. The effect of multiple pthread_detach() calls on the same target thread is unspecified.

RETURN VALUE

If the call succeeds, pthread_detach() shall return 0; otherwise, an error number shall be returned to indicate the error.

ERRORS

The pthread_detach() function may fail if:

[EINVAL]

The implementation has detected that the value specified by thread does not refer to a joinable thread.

[ESRCH]

No thread could be found corresponding to that specified by the given thread ID.

The pthread_detach() function shall not return an error code of [EINTR].

EXAMPLES

None.

APPLICATION USAGE

None.

RATIONALE

The pthread_join() or pthread_detach() functions should eventually be called for every thread that is created so that storage associated with the thread may be reclaimed.

It has been suggested that a "detach" function is not necessary; the detachstate thread creation attribute is sufficient, since a thread need never be dynamically detached. However, need arises in at least two cases:

1. In a cancellation handler for a pthread_join() it is nearly essential to have a pthread_detach() function in order to detach the thread on which pthread_join() was waiting. Without it, it would be necessary to have the handler do another pthread_join() to attempt to detach the thread, which would both delay the cancellation processing for an unbounded period and introduce a new call to pthread_join(), which might itself need a cancellation handler. A dynamic detach is nearly essential in this case.

2. In order to detach the "initial thread" (as may be desirable in processes that set up server threads).

FUTURE DIRECTIONS

None.

SEE ALSO

pthread_join(), the Base Definitions volume of IEEE Std 1003.1-2001, <pthread.h>

CHANGE HISTORY

First released in Issue 5. Included for alignment with the POSIX Threads Extension.

Issue 6

The pthread_detach() function is marked as part of the Threads option.

IEEE Std 1003.1-2001/Cor 2-2004, item XSH/TC2/D6/95 is applied, updating the ERRORS section so that the [EINVAL] and [ESRCH] error cases become optional.