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.
The pthread_mutex_timedlock() function shall lock the mutex object
referenced by mutex. If the mutex is already locked, the calling
thread shall block until the mutex becomes available as in the
pthread_mutex_lock() function. If the mutex cannot be locked without
waiting for another thread to unlock the mutex, this wait shall be
terminated when the specified timeout expires.
The timeout shall expire when the absolute time specified by abstime
passes, as measured by the clock on which timeouts are based (that
is, when the value of that clock equals or exceeds abstime), or if
the absolute time specified by abstime has already been passed at the
time of the call.
The timeout shall be based on the CLOCK_REALTIME clock. The
resolution of the timeout shall be the resolution of the clock on
which it is based. The timespec data type is defined in the <time.h>
Under no circumstance shall the function fail with a timeout if the
mutex can be locked immediately. The validity of the abstime
parameter need not be checked if the mutex can be locked immediately.
As a consequence of the priority inheritance rules (for mutexes
initialized with the PRIO_INHERIT protocol), if a timed mutex wait is
terminated because its timeout expires, the priority of the owner of
the mutex shall be adjusted as necessary to reflect the fact that
this thread is no longer among the threads waiting for the mutex.
If mutex is a robust mutex and the process containing the owning
thread terminated while holding the mutex lock, a call to
pthread_mutex_timedlock() shall return the error value [EOWNERDEAD].
If mutex is a robust mutex and the owning thread terminated while
holding the mutex lock, a call to pthread_mutex_timedlock() may
return the error value [EOWNERDEAD] even if the process in which the
owning thread resides has not terminated. In these cases, the mutex
is locked by the thread but the state it protects is marked as
inconsistent. The application should ensure that the state is made
consistent for reuse and when that is complete call
pthread_mutex_consistent(). If the application is unable to recover
the state, it should unlock the mutex without a prior call to
pthread_mutex_consistent(), after which the mutex is marked
If mutex does not refer to an initialized mutex object, the behavior
The pthread_mutex_timedlock() function shall fail if:
EAGAIN The mutex could not be acquired because the maximum number of
recursive locks for mutex has been exceeded.
The mutex type is PTHREAD_MUTEX_ERRORCHECK and the current
thread already owns the mutex.
EINVAL The mutex was created with the protocol attribute having the
value PTHREAD_PRIO_PROTECT and the calling thread's priority
is higher than the mutex' current priority ceiling.
EINVAL The process or thread would have blocked, and the abstime
parameter specified a nanoseconds field value less than zero
or greater than or equal to 1000 million.
The state protected by the mutex is not recoverable.
The mutex is a robust mutex and the process containing the
previous owning thread terminated while holding the mutex
lock. The mutex lock shall be acquired by the calling thread
and it is up to the new owner to make the state consistent.
The mutex could not be locked before the specified timeout
The pthread_mutex_timedlock() function may fail if:
A deadlock condition was detected.
The mutex is a robust mutex and the previous owning thread
terminated while holding the mutex lock. The mutex lock shall
be acquired by the calling thread and it is up to the new
owner to make the state consistent.
This function shall not return an error code of [EINTR].
The following sections are informative.
Applications that have assumed that non-zero return values are errors
will need updating for use with robust mutexes, since a valid return
for a thread acquiring a mutex which is protecting a currently
inconsistent state is [EOWNERDEAD]. Applications that do not check
the error returns, due to ruling out the possibility of such errors
arising, should not use robust mutexes. If an application is supposed
to work with normal and robust mutexes, it should check all return
values for error conditions and if necessary take appropriate action.
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
IEEE/The Open Group 2013 PTHREAD_MUTEX_TIMEDLOCK(3P)