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PTHREAD_JOIN(3) FreeBSD Library Functions Manual PTHREAD_JOIN(3)
NAME pthread_join, pthread_peekjoin_np, pthread_timedjoin_np - inspect thread termination state
LIBRARY POSIX Threads Library (libpthread, -lpthread)
SYNOPSIS #include <pthread.h>
int pthread_join(pthread_t thread, void **value_ptr);
#include <pthread_np.h>
int pthread_peekjoin_np(pthread_t thread, void **value_ptr);
int pthread_timedjoin_np(pthread_t thread, void **value_ptr, const struct timespec *abstime);
DESCRIPTION The pthread_join() function suspends execution of the calling thread until the target thread terminates unless the target thread has already terminated.
On return from a successful pthread_join() call with a non-NULL value_ptr argument, the value passed to pthread_exit() by the terminating thread is stored in the location referenced by value_ptr. When a pthread_join() returns successfully, the target thread has been terminated. The results of multiple simultaneous calls to pthread_join() specifying the same target thread are undefined. If the thread calling pthread_join() is cancelled, then the target thread is not detached.
The pthread_timedjoin_np() function is equivalent to the pthread_join() function except it will return ETIMEDOUT if target thread does not exit before specified absolute time passes.
The pthread_peekjoin_np() only peeks into the exit status of the specified thread. If the thread has not exited, the EBUSY error is returned. Otherwise, zero is returned and the thread exit value is optionally stored into the location of *value_ptr. The target thread is left unjoined and can be used as an argument for the pthread_join() family of functions again.
A thread that has exited but remains unjoined counts against [_POSIX_THREAD_THREADS_MAX].
RETURN VALUES If successful, the described functions return zero. Otherwise an error number is returned to indicate the error or special condition.
ERRORS The pthread_join(), pthread_peekjoin_np(), and pthread_timedjoin_np() functions will fail if:
[EDEADLK] A deadlock was detected or the value of thread specifies the calling thread.
[EOPNOTSUPP] The implementation detected that another caller is already waiting on thread.
Additionally, the pthread_timedjoin_np() function will fail if:
[ETIMEDOUT] The specified absolute time passed while pthread_timedjoin_np() waited for thread exit.
The pthread_peekjoin_np() function will also fail if:
[EBUSY] The specified thread has not yet exited.
SEE ALSO wait(2), pthread(3), pthread_create(3), pthread_np(3)
STANDARDS The pthread_join() function conforms to ISO/IEC 9945-1:1996 ("POSIX.1"). The pthread_timedjoin_np() function is a FreeBSD extension which first appeared in FreeBSD 6.1. Another extension, the pthread_peekjoin_np() function, first appearead in FreeBSD 13.0.
FreeBSD 14.0-RELEASE-p6 October 12, 2021 FreeBSD 14.0-RELEASE-p6