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Diffstat (limited to 'man3/pthread_join.3')
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diff --git a/man3/pthread_join.3 b/man3/pthread_join.3 new file mode 100644 index 0000000..9284d85 --- /dev/null +++ b/man3/pthread_join.3 @@ -0,0 +1,135 @@ +'\" t +.\" Copyright (c) 2008 Linux Foundation, written by Michael Kerrisk +.\" <mtk.manpages@gmail.com> +.\" +.\" SPDX-License-Identifier: Linux-man-pages-copyleft +.\" +.TH pthread_join 3 2023-07-20 "Linux man-pages 6.05.01" +.SH NAME +pthread_join \- join with a terminated thread +.SH LIBRARY +POSIX threads library +.RI ( libpthread ", " \-lpthread ) +.SH SYNOPSIS +.nf +.B #include <pthread.h> +.PP +.BI "int pthread_join(pthread_t " thread ", void **" retval ); +.fi +.SH DESCRIPTION +The +.BR pthread_join () +function waits for the thread specified by +.I thread +to terminate. +If that thread has already terminated, then +.BR pthread_join () +returns immediately. +The thread specified by +.I thread +must be joinable. +.PP +If +.I retval +is not NULL, then +.BR pthread_join () +copies the exit status of the target thread +(i.e., the value that the target thread supplied to +.BR pthread_exit (3)) +into the location pointed to by +.IR retval . +If the target thread was canceled, then +.B PTHREAD_CANCELED +is placed in the location pointed to by +.IR retval . +.PP +If multiple threads simultaneously try to join with the same thread, +the results are undefined. +If the thread calling +.BR pthread_join () +is canceled, then the target thread will remain joinable +(i.e., it will not be detached). +.SH RETURN VALUE +On success, +.BR pthread_join () +returns 0; +on error, it returns an error number. +.SH ERRORS +.TP +.B EDEADLK +A deadlock was detected +.\" The following verified by testing on glibc 2.8/NPTL: +(e.g., two threads tried to join with each other); +or +.\" The following verified by testing on glibc 2.8/NPTL: +.I thread +specifies the calling thread. +.TP +.B EINVAL +.I thread +is not a joinable thread. +.TP +.B EINVAL +Another thread is already waiting to join with this thread. +.\" POSIX.1-2001 does not specify this error case. +.TP +.B ESRCH +No thread with the ID +.I thread +could be found. +.SH ATTRIBUTES +For an explanation of the terms used in this section, see +.BR attributes (7). +.TS +allbox; +lbx lb lb +l l l. +Interface Attribute Value +T{ +.na +.nh +.BR pthread_join () +T} Thread safety MT-Safe +.TE +.sp 1 +.SH STANDARDS +POSIX.1-2008. +.SH HISTORY +POSIX.1-2001. +.SH NOTES +After a successful call to +.BR 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). +.PP +Joining with a thread that has previously been joined results in +undefined behavior. +.PP +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). +.PP +There is no pthreads analog of +.IR "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. +.PP +All of the threads in a process are peers: +any thread can join with any other thread in the process. +.SH EXAMPLES +See +.BR pthread_create (3). +.SH SEE ALSO +.BR pthread_cancel (3), +.BR pthread_create (3), +.BR pthread_detach (3), +.BR pthread_exit (3), +.BR pthread_tryjoin_np (3), +.BR pthreads (7) |