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NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | ATTRIBUTES | STANDARDS | HISTORY | NOTES | EXAMPLES | SEE ALSO | COLOPHON |
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pthread_join(3) Library Functions Manual pthread_join(3)
pthread_join - join with a terminated thread
POSIX threads library (libpthread, -lpthread)
#include <pthread.h>
int pthread_join(pthread_t thread, void **retval);
The pthread_join() function waits for the thread specified by
thread to terminate. If that thread has already terminated, then
pthread_join() returns immediately. The thread specified by
thread must be joinable.
If retval is not NULL, then pthread_join() copies the exit status
of the target thread (i.e., the value that the target thread
supplied to pthread_exit(3)) into the location pointed to by
retval. If the target thread was canceled, then PTHREAD_CANCELED
is placed in the location pointed to by retval.
If multiple threads simultaneously try to join with the same
thread, the results are undefined. If the thread calling
pthread_join() is canceled, then the target thread will remain
joinable (i.e., it will not be detached).
On success, pthread_join() returns 0; on error, it returns an
error number.
EDEADLK
A deadlock was detected (e.g., two threads tried to join
with each other); or thread specifies the calling thread.
EINVAL thread is not a joinable thread.
EINVAL Another thread is already waiting to join with this
thread.
ESRCH No thread with the ID thread could be found.
For an explanation of the terms used in this section, see
attributes(7).
┌─────────────────────────────────────┬───────────────┬─────────┐
│ Interface │ Attribute │ Value │
├─────────────────────────────────────┼───────────────┼─────────┤
│ pthread_join() │ Thread safety │ MT-Safe │
└─────────────────────────────────────┴───────────────┴─────────┘
POSIX.1-2008.
POSIX.1-2001.
After a successful call to pthread_join(), the caller is
guaranteed that the target thread has terminated. The caller may
then choose to do any clean-up that is required after termination
of the thread (e.g., freeing memory or other resources that were
allocated to the target thread).
Joining with a thread that has previously been joined results in
undefined behavior.
Failure to join with a thread that is joinable (i.e., one that is
not detached), produces a "zombie thread". Avoid doing this,
since each zombie thread consumes some system resources, and when
enough zombie threads have accumulated, it will no longer be
possible to create new threads (or processes).
There is no pthreads analog of waitpid(-1, &status, 0), that is,
"join with any terminated thread". If you believe you need this
functionality, you probably need to rethink your application
design.
All of the threads in a process are peers: any thread can join
with any other thread in the process.
See pthread_create(3).
pthread_cancel(3), pthread_create(3), pthread_detach(3),
pthread_exit(3), pthread_tryjoin_np(3), pthreads(7)
This page is part of the man-pages (Linux kernel and C library
user-space interface documentation) project. Information about
the project can be found at
⟨https://www.kernel.org/doc/man-pages/⟩. If you have a bug report
for this manual page, see
⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.
This page was obtained from the tarball man-pages-6.9.1.tar.gz
fetched from
⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on
2024-06-26. If you discover any rendering problems in this HTML
version of the page, or you believe there is a better or more up-
to-date source for the page, or you have corrections or
improvements to the information in this COLOPHON (which is not
part of the original manual page), send a mail to
man-pages@man7.org
Linux man-pages 6.9.1 2024-05-02 pthread_join(3)
Pages that refer to this page: pthread_attr_setdetachstate(3), pthread_cancel(3), pthread_create(3), pthread_detach(3), pthread_exit(3), pthread_tryjoin_np(3)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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