pthread_barrier_wait(3p) — Linux manual page

PTHREAD_...IER_WAIT(3P) POSIX Programmer's ManualPTHREAD_...IER_WAIT(3P)

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.

NAME

       pthread_barrier_wait — synchronize at a barrier

SYNOPSIS

       #include <pthread.h>

       int pthread_barrier_wait(pthread_barrier_t *barrier);

DESCRIPTION

       The pthread_barrier_wait() function shall synchronize
       participating threads at the barrier referenced by barrier.  The
       calling thread shall block until the required number of threads
       have called pthread_barrier_wait() specifying the barrier.

       When the required number of threads have called
       pthread_barrier_wait() specifying the barrier, the constant
       PTHREAD_BARRIER_SERIAL_THREAD shall be returned to one
       unspecified thread and zero shall be returned to each of the
       remaining threads. At this point, the barrier shall be reset to
       the state it had as a result of the most recent
       pthread_barrier_init() function that referenced it.

       The constant PTHREAD_BARRIER_SERIAL_THREAD is defined in
       <pthread.h> and its value shall be distinct from any other value
       returned by pthread_barrier_wait().

       The results are undefined if this function is called with an
       uninitialized barrier.

       If a signal is delivered to a thread blocked on a barrier, upon
       return from the signal handler the thread shall resume waiting at
       the barrier if the barrier wait has not completed (that is, if
       the required number of threads have not arrived at the barrier
       during the execution of the signal handler); otherwise, the
       thread shall continue as normal from the completed barrier wait.
       Until the thread in the signal handler returns from it, it is
       unspecified whether other threads may proceed past the barrier
       once they have all reached it.

       A thread that has blocked on a barrier shall not prevent any
       unblocked thread that is eligible to use the same processing
       resources from eventually making forward progress in its
       execution. Eligibility for processing resources shall be
       determined by the scheduling policy.

RETURN VALUE

       Upon successful completion, the pthread_barrier_wait() function
       shall return PTHREAD_BARRIER_SERIAL_THREAD for a single
       (arbitrary) thread synchronized at the barrier and zero for each
       of the other threads. Otherwise, an error number shall be
       returned to indicate the error.

ERRORS

       This function shall not return an error code of [EINTR].

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       Applications using this function may be subject to priority
       inversion, as discussed in the Base Definitions volume of
       POSIX.1‐2017, Section 3.291, Priority Inversion.

RATIONALE

       If an implementation detects that the value specified by the
       barrier argument to pthread_barrier_wait() does not refer to an
       initialized barrier object, it is recommended that the function
       should fail and report an [EINVAL] error.

FUTURE DIRECTIONS

       None.

SEE ALSO

       pthread_barrier_destroy(3p)

       The Base Definitions volume of POSIX.1‐2017, Section 3.291,
       Priority Inversion, Section 4.12, Memory Synchronization,
       pthread.h(0p)

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic
       form from IEEE Std 1003.1-2017, Standard for Information
       Technology -- Portable Operating System Interface (POSIX), The
       Open Group Base Specifications Issue 7, 2018 Edition, Copyright
       (C) 2018 by the Institute of Electrical and Electronics
       Engineers, Inc and The Open Group.  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.opengroup.org/unix/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 .

IEEE/The Open Group               2017           PTHREAD_...IER_WAIT(3P)

Pages that refer to this page: pthread.h(0p), pthread_barrier_destroy(3p)

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