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All Rights Reserved. .\" Portions Copyright (c) 2004, Sun Microsystems, Inc. All Rights Reserved. .\" .TH PTHREAD_BARRIER_WAIT 3C "Jan 30, 2004" .SH NAME pthread_barrier_wait \- synchronize at a barrier .SH SYNOPSIS .LP .nf cc \fB-mt\fR [ \fIflag\fR... ] \fIfile\fR... [ \fIlibrary\fR... ] #include <pthread.h> \fBint\fR \fBpthread_barrier_wait\fR(\fBpthread_barrier_t *\fR\fIbarrier\fR); .fi .SH DESCRIPTION .sp .LP The \fBpthread_barrier_wait()\fR function synchronizes participating threads at the barrier referenced by \fIbarrier\fR. The calling thread blocks until the required number of threads have called \fBpthread_barrier_wait()\fR specifying the barrier. .sp .LP When the required number of threads have called \fBpthread_barrier_wait()\fR specifying the barrier, the constant \fBPTHREAD_BARRIER_SERIAL_THREAD\fR is returned to one unspecified thread and 0 is returned to each of the remaining threads. At this point, the barrier is reset to the state it had as a result of the most recent \fBpthread_barrier_init\fR(3C) function that referenced it. .sp .LP The constant \fBPTHREAD_BARRIER_SERIAL_THREAD\fR is defined in <\fBpthread.h\fR> and its value is distinct from any other value returned by \fBpthread_barrier_wait()\fR. .sp .LP The results are undefined if this function is called with an uninitialized barrier. .sp .LP If a signal is delivered to a thread blocked on a barrier, upon return from the signal handler the thread resumes 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 continues 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. .sp .LP A thread that has blocked on a barrier does not prevent any unblocked thread that is eligible to use the same processing resources from eventually making forward progress in its execution. .sp .LP Eligibility for processing resources is determined by the scheduling policy. .SH RETURN VALUES .sp .LP Upon successful completion, the \fBpthread_barrier_wait()\fR function returns \fBPTHREAD_BARRIER_SERIAL_THREAD\fR for a single (arbitrary) thread synchronized at the barrier and 0 for each of the other threads. Otherwise, an error number is returned to indicate the error. .SH ERRORS .sp .LP The \fBpthread_barrier_wait()\fR function will fail if: .sp .ne 2 .na \fB\fBEINVAL\fR\fR .ad .RS 10n The value specified by \fIbarrier\fR does not refer to an initialized barrier object. .RE .SH ATTRIBUTES .sp .LP See \fBattributes\fR(7) for descriptions of the following attributes: .sp .sp .TS box; c | c l | l . ATTRIBUTE TYPE ATTRIBUTE VALUE _ Interface Stability Standard _ MT-Level MT-Safe .TE .SH SEE ALSO .sp .LP .BR pthread_barrier_destroy (3C), .BR attributes (7), .BR standards (7)