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)
