1PTHREAD_BARRIER_WAIT(3P) POSIX Programmer's Manual PTHREAD_BARRIER_WAIT(3P)
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6 This manual page is part of the POSIX Programmer's Manual. The Linux
7 implementation of this interface may differ (consult the corresponding
8 Linux manual page for details of Linux behavior), or the interface may
9 not be implemented on Linux.
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12 pthread_barrier_wait - synchronize at a barrier (ADVANCED REALTIME
13 THREADS)
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16 #include <pthread.h>
17 int pthread_barrier_wait(pthread_barrier_t *barrier);
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22 The pthread_barrier_wait() function shall synchronize participating
23 threads at the barrier referenced by barrier. The calling thread shall
24 block until the required number of threads have called pthread_bar‐
25 rier_wait() specifying the barrier.
26 When the required number of threads have called pthread_barrier_wait()
28 specifying the barrier, the constant PTHREAD_BARRIER_SERIAL_THREAD
29 shall be returned to one unspecified thread and zero shall be returned
30 to each of the remaining threads. At this point, the barrier shall be
31 reset to the state it had as a result of the most recent pthread_bar‐
32 rier_init() function that referenced it.
33 The constant PTHREAD_BARRIER_SERIAL_THREAD is defined in <pthread.h>
35 and its value shall be distinct from any other value returned by
36 pthread_barrier_wait().
37 The results are undefined if this function is called with an uninitial‐
39 ized barrier.
40 If a signal is delivered to a thread blocked on a barrier, upon return
42 from the signal handler the thread shall resume waiting at the barrier
43 if the barrier wait has not completed (that is, if the required number
44 of threads have not arrived at the barrier during the execution of the
45 signal handler); otherwise, the thread shall continue as normal from
46 the completed barrier wait. Until the thread in the signal handler
47 returns from it, it is unspecified whether other threads may proceed
48 past the barrier once they have all reached it.
49 A thread that has blocked on a barrier shall not prevent any unblocked
51 thread that is eligible to use the same processing resources from even‐
52 tually making forward progress in its execution. Eligibility for pro‐
53 cessing resources shall be determined by the scheduling policy.
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56 Upon successful completion, the pthread_barrier_wait() function shall
57 return PTHREAD_BARRIER_SERIAL_THREAD for a single (arbitrary) thread
58 synchronized at the barrier and zero for each of the other threads.
59 Otherwise, an error number shall be returned to indicate the error.
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62 The pthread_barrier_wait() function may fail if:
63 EINVAL The value specified by barrier does not refer to an initialized
65 barrier object.
66 This function shall not return an error code of [EINTR].
69 The following sections are informative.
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73 None.
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76 Applications using this function may be subject to priority inversion,
77 as discussed in the Base Definitions volume of IEEE Std 1003.1-2001,
78 Section 3.285, Priority Inversion.
79 The pthread_barrier_wait() function is part of the Barriers option and
81 need not be provided on all implementations.
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84 None.
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87 None.
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90 pthread_barrier_destroy(), the Base Definitions volume of
91 IEEE Std 1003.1-2001, <pthread.h>
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94 Portions of this text are reprinted and reproduced in electronic form
95 from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
96 -- Portable Operating System Interface (POSIX), The Open Group Base
97 Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
98 Electrical and Electronics Engineers, Inc and The Open Group. In the
99 event of any discrepancy between this version and the original IEEE and
100 The Open Group Standard, the original IEEE and The Open Group Standard
101 is the referee document. The original Standard can be obtained online
102 at http://www.opengroup.org/unix/online.html .
103IEEE/The Open Group 2003 PTHREAD_BARRIER_WAIT(3P)