pthread_mutex_init(3)					     Library Functions Manual					     pthread_mutex_init(3)

NAME

       pthread_mutex_init - Initializes a mutex.

LIBRARY

       DECthreads POSIX 1003.1c Library (libpthread.so)

SYNOPSIS

       #include <pthread.h>

       int   pthread_mutex_init(
			     pthread_mutex_t   *mutex,
			     const pthread_mutexattr_t *attr);

STANDARDS

       Interfaces documented on this reference page conform to industry standards as follows:

       IEEE Std 1003.1c-1995, POSIX System Application Program Interface

PARAMETERS

       Mutex to be initialized.  Mutex attributes object that defines the characteristics of the mutex to be initialized.

DESCRIPTION

       This routine initializes a mutex with the attributes specified by the mutex attributes object specified in the attr argument.  A mutex is a
       synchronization object that allows multiple threads to serialize their access to shared data.

       The mutex is initialized and set to the unlocked state.	If attr is set to NULL, the default mutex attributes are used.	The pthread_mutex-
       attr_settype(3) routine can be used to specify the type of mutex that is created (normal, recursive, or errorcheck).

       Use the PTHREAD_MUTEX_INITIALIZER macro to statically initialize a mutex without calling this routine.  Statically initialized mutexes need
       not be destroyed using pthread_mutex_destroy(3).  Use this macro as follows:

       pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER

       Only normal mutexes can be statically initialized.

       A mutex is a resource of the process, not part of any particular thread.  A mutex is neither destroyed nor unlocked automatically when  any
       thread exits.  If a mutex is allocated on a stack, static initializers cannot be used on the mutex.

RETURN VALUES

       If  an  error  condition  occurs, this routine returns an integer value indicating the type of error, the mutex is not initialized, and the
       contents of mutex are undefined.  Possible return values are as follows: Successful completion.	The system lacks the  necessary  resources
       to  initialize  the  mutex.   The  implementation  has detected an attempt to reinitialize the mutex (a previously initialized, but not yet
       destroyed mutex).  The value specified by mutex is not a valid mutex.  Insufficient memory exists to initialize the mutex.  The caller does
       not have privileges to perform the operation.

ERRORS

       None

RELATED INFORMATION

       Functions: pthread_mutexattr_init(3), pthread_mutexattr_gettype(3), pthread_mutexattr_settype(3), pthread_mutex_lock(3), pthread_mutex_try-
       lock(3), pthread_mutex_unlock(3)

       Manuals: Guide to DECthreads and Programmer's Guide

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															     pthread_mutex_init(3)