diff options
Diffstat (limited to 'man-pages-posix-2013/man3p/pthread_join.3p')
| -rw-r--r-- | man-pages-posix-2013/man3p/pthread_join.3p | 230 |
1 files changed, 230 insertions, 0 deletions
diff --git a/man-pages-posix-2013/man3p/pthread_join.3p b/man-pages-posix-2013/man3p/pthread_join.3p new file mode 100644 index 0000000..5ba8bf3 --- /dev/null +++ b/man-pages-posix-2013/man3p/pthread_join.3p @@ -0,0 +1,230 @@ +'\" et +.TH PTHREAD_JOIN "3P" 2013 "IEEE/The Open Group" "POSIX Programmer's Manual" +.SH PROLOG +This manual page is part of the POSIX Programmer's Manual. +The Linux implementation of this interface may differ (consult +the corresponding Linux manual page for details of Linux behavior), +or the interface may not be implemented on Linux. + +.SH NAME +pthread_join +\(em wait for thread termination +.SH SYNOPSIS +.LP +.nf +#include <pthread.h> +.P +int pthread_join(pthread_t \fIthread\fP, void **\fIvalue_ptr\fP); +.fi +.SH DESCRIPTION +The +\fIpthread_join\fR() +function shall suspend execution of the calling thread until the target +.IR thread +terminates, unless the target +.IR thread +has already terminated. On return from a successful +\fIpthread_join\fR() +call with a non-NULL +.IR value_ptr +argument, the value passed to +\fIpthread_exit\fR() +by the terminating thread shall be made available in the location +referenced by +.IR value_ptr . +When a +\fIpthread_join\fR() +returns successfully, the target thread has been terminated. The +results of multiple simultaneous calls to +\fIpthread_join\fR() +specifying the same target thread are undefined. If the thread calling +\fIpthread_join\fR() +is canceled, then the target thread shall not be detached. +.P +It is unspecified whether a thread that has exited but remains unjoined +counts against +{PTHREAD_THREADS_MAX}. +.P +The behavior is undefined if the value specified by the +.IR thread +argument to +\fIpthread_join\fR() +does not refer to a joinable thread. +.P +The behavior is undefined if the value specified by the +.IR thread +argument to +\fIpthread_join\fR() +refers to the calling thread. +.SH "RETURN VALUE" +If successful, the +\fIpthread_join\fR() +function shall return zero; otherwise, an error number shall be +returned to indicate the error. +.SH ERRORS +The +\fIpthread_join\fR() +function may fail if: +.TP +.BR EDEADLK +A deadlock was detected. +.P +The +\fIpthread_join\fR() +function shall not return an error code of +.BR [EINTR] . +.LP +.IR "The following sections are informative." +.SH EXAMPLES +An example of thread creation and deletion follows: +.sp +.RS 4 +.nf +\fB +typedef struct { + int *ar; + long n; +} subarray; +.P +void * +incer(void *arg) +{ + long i; +.P + for (i = 0; i < ((subarray *)arg)->n; i++) + ((subarray *)arg)->ar[i]++; +} +.P +int main(void) +{ + int ar[1000000]; + pthread_t th1, th2; + subarray sb1, sb2; +.P + sb1.ar = &ar[0]; + sb1.n = 500000; + (void) pthread_create(&th1, NULL, incer, &sb1); +.P + sb2.ar = &ar[500000]; + sb2.n = 500000; + (void) pthread_create(&th2, NULL, incer, &sb2); +.P + (void) pthread_join(th1, NULL); + (void) pthread_join(th2, NULL); + return 0; +} +.fi \fR +.P +.RE +.SH "APPLICATION USAGE" +None. +.SH RATIONALE +The +\fIpthread_join\fR() +function is a convenience that has proven useful in multi-threaded +applications. It is true that a programmer could simulate this +function if it were not provided by passing extra state as part of the +argument to the +\fIstart_routine\fR(). +The terminating thread would set a flag to indicate termination and +broadcast a condition that is part of that state; a joining thread +would wait on that condition variable. While such a technique would +allow a thread to wait on more complex conditions (for example, waiting +for multiple threads to terminate), waiting on individual thread +termination is considered widely useful. Also, including the +\fIpthread_join\fR() +function in no way precludes a programmer from coding such complex +waits. Thus, while not a primitive, including +\fIpthread_join\fR() +in this volume of POSIX.1\(hy2008 was considered valuable. +.P +The +\fIpthread_join\fR() +function provides a simple mechanism allowing an application to wait +for a thread to terminate. After the thread terminates, the +application may then choose to clean up resources that were used by the +thread. For instance, after +\fIpthread_join\fR() +returns, any application-provided stack storage could be reclaimed. +.P +The +\fIpthread_join\fR() +or +\fIpthread_detach\fR() +function should eventually be called for every thread that is created +with the +.IR detachstate +attribute set to PTHREAD_CREATE_JOINABLE +so that storage associated with the thread may be reclaimed. +.P +The interaction between +\fIpthread_join\fR() +and cancellation is well-defined for the following reasons: +.IP " *" 4 +The +\fIpthread_join\fR() +function, like all other non-async-cancel-safe functions, can only be +called with +deferred cancelability type. +.IP " *" 4 +Cancellation cannot occur in the disabled cancelability state. +.P +Thus, only the default cancelability state need be considered. As +specified, either the +\fIpthread_join\fR() +call is canceled, or it succeeds, but not both. The difference is +obvious to the application, since either a cancellation handler is run +or +\fIpthread_join\fR() +returns. There are no race conditions since +\fIpthread_join\fR() +was called in the deferred cancelability state. +.P +If an implementation detects that the value specified by the +.IR thread +argument to +\fIpthread_join\fR() +does not refer to a joinable thread, it is recommended that the +function should fail and report an +.BR [EINVAL] +error. +.P +If an implementation detects that the value specified by the +.IR thread +argument to +\fIpthread_join\fR() +refers to the calling thread, it is recommended that the function +should fail and report an +.BR [EDEADLK] +error. +.P +If an implementation detects use of a thread ID after the end of its +lifetime, it is recommended that the function should fail and report an +.BR [ESRCH] +error. +.SH "FUTURE DIRECTIONS" +None. +.SH "SEE ALSO" +.IR "\fIpthread_create\fR\^(\|)", +.IR "\fIwait\fR\^(\|)" +.P +The Base Definitions volume of POSIX.1\(hy2008, +.IR "Section 4.11" ", " "Memory Synchronization", +.IR "\fB<pthread.h>\fP" +.SH COPYRIGHT +Portions of this text are reprinted and reproduced in electronic form +from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology +-- Portable Operating System Interface (POSIX), The Open Group Base +Specifications Issue 7, Copyright (C) 2013 by the Institute of +Electrical and Electronics Engineers, Inc and The Open Group. +(This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the +event of any discrepancy between this version and the original IEEE and +The Open Group Standard, the original IEEE and The Open Group Standard +is the referee document. The original Standard can be obtained online at +http://www.unix.org/online.html . + +Any typographical or formatting errors that appear +in this page are most likely +to have been introduced during the conversion of the source files to +man page format. To report such errors, see +https://www.kernel.org/doc/man-pages/reporting_bugs.html . |