PTHREAD_JOIN(3) | Library Functions Manual | PTHREAD_JOIN(3)

# NAME

`pthread_join` — wait for thread termination

# SYNOPSIS

POSIX Threads Library (libpthread, -lpthread)
`#include <pthread.h>`

int
`pthread_join`(pthread_t thread, void **value_ptr);

# 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.

A thread that has exited but remains unjoined counts against [_POSIX_THREAD_THREADS_MAX].

# RETURN VALUES

If successful, the `pthread_join`() function will return zero. Otherwise an error number will be returned to indicate the error.

# ERRORS

`pthread_join`() will 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, thread.
[`EDEADLK`]
  A deadlock was detected or the value of thread specifies the calling thread.

# SEE ALSO

wait(2), pthread_create(3)

# STANDARDS

`pthread_join`() conforms to ISO/IEC 9945-1:1996 (“POSIX.1”).

June 7, 2025 | Debian