NAME

pthread — POSIX thread functions

SYNOPSIS

#include <pthread.h>

DESCRIPTION

POSIX threads are a set of functions that support applications with requirements for multiple flows of control, called threads, within a process. Multithreading is used to improve the performance of a program.

The POSIX thread functions are summarized in this section in the following groups:

Thread Routines
Attribute Object Routines
Mutex Routines
Condition Variable Routines
Read/Write Lock Routines
Per-Thread Context Routines
Cleanup Routines

Thread Routines

int pthread_create(pthread_t *thread, const pthread_attr_t *attr, void *(*start_routine)(void *), void *arg);: Creates a new thread of execution.
int pthread_cancel(pthread_t thread): Cancels execution of a thread.
int pthread_detach(pthread_t thread): Marks a thread for deletion.
int pthread_equal(pthread_t t1, pthread_t t2): Compares two thread IDs.
void pthread_exit(void *value_ptr): Terminates the calling thread.
int pthread_join(pthread_t thread, void **value_ptr): Causes the calling thread to wait for the termination of the specified thread.
int pthread_kill(pthread_t thread, int sig): Delivers a signal to a specified thread.
int pthread_once(pthread_once_t *once_control, void (*init_routine)(void)): Calls an initialization routine once.
pthread_t pthread_self(void): Returns the thread ID of the calling thread.
int pthread_setcancelstate(int state, int *oldstate): Sets the current thread's cancelability state.
int pthread_setcanceltype(int type, int *oldtype): Sets the current thread's cancelability type.
void pthread_testcancel(void): Creates a cancellation point in the calling thread.

Attribute Object Routines

int pthread_attr_destroy(pthread_attr_t *attr): Destroy a thread attributes object.
int pthread_attr_getinheritsched(const pthread_attr_t *attr, int *inheritsched);: Get the inherit scheduling attribute from a thread attributes object.
int pthread_attr_getschedparam(const pthread_attr_t *attr, struct sched_param *param);: Get the scheduling parameter attribute from a thread attributes object.
int pthread_attr_getschedpolicy(const pthread_attr_t *attr, int *policy): Get the scheduling policy attribute from a thread attributes object.
int pthread_attr_getscope(const pthread_attr_t *attr, int *contentionscope): Get the contention scope attribute from a thread attributes object.
int pthread_attr_getstacksize(const pthread_attr_t *attr, size_t *stacksize): Get the stack size attribute from a thread attributes object.
int pthread_attr_getstackaddr(const pthread_attr_t *attr, void **stackaddr): Get the stack address attribute from a thread attributes object.
int pthread_attr_getdetachstate(const pthread_attr_t *attr, int *detachstate): Get the detach state attribute from a thread attributes object.
int pthread_attr_init(pthread_attr_t *attr): Initialize a thread attributes object with default values.
int pthread_attr_setinheritsched(pthread_attr_t *attr, int inheritsched): Set the inherit scheduling attribute in a thread attributes object.
int pthread_attr_setschedparam(pthread_attr_t *attr, const struct sched_param *param);: Set the scheduling parameter attribute in a thread attributes object.
int pthread_attr_setschedpolicy(pthread_attr_t *attr, int policy): Set the scheduling policy attribute in a thread attributes object.
int pthread_attr_setscope(pthread_attr_t *attr, int contentionscope): Set the contention scope attribute in a thread attributes object.
int pthread_attr_setstacksize(pthread_attr_t *attr, size_t stacksize): Set the stack size attribute in a thread attributes object.
int pthread_attr_setstackaddr(pthread_attr_t *attr, void *stackaddr): Set the stack address attribute in a thread attributes object.
int pthread_attr_setdetachstate(pthread_attr_t *attr, int detachstate): Set the detach state in a thread attributes object.

Mutex Routines

int pthread_mutexattr_destroy(pthread_mutexattr_t *attr): Destroy a mutex attributes object.
int pthread_mutexattr_getprioceiling(pthread_mutexattr_t *attr, int *ceiling): Obtain priority ceiling attribute of mutex attribute object.
int pthread_mutexattr_getprotocol(pthread_mutexattr_t *attr, int *protocol): Obtain protocol attribute of mutex attribute object.
int pthread_mutexattr_gettype(pthread_mutexattr_t *attr, int *type): Obtain the mutex type attribute in the specified mutex attributes object.
int pthread_mutexattr_init(pthread_mutexattr_t *attr): Initialize a mutex attributes object with default values.
int pthread_mutexattr_setprioceiling(pthread_mutexattr_t *attr, int ceiling): Set priority ceiling attribute of mutex attribute object.
int pthread_mutexattr_setprotocol(pthread_mutexattr_t *attr, int protocol): Set protocol attribute of mutex attribute object.
int pthread_mutexattr_settype(pthread_mutexattr_t *attr, int type): Set the mutex type attribute that is used when a mutex is created.
int pthread_mutex_destroy(pthread_mutex_t *mutex): Destroy a mutex.
int pthread_mutex_init(pthread_mutex_t *mutex, const pthread_mutexattr_t *attr);: Initialize a mutex with specified attributes.
int pthread_mutex_lock(pthread_mutex_t *mutex): Lock a mutex and block until it becomes available.
int pthread_mutex_trylock(pthread_mutex_t *mutex): Try to lock a mutex, but do not block if the mutex is locked by another thread, including the current thread.
int pthread_mutex_unlock(pthread_mutex_t *mutex): Unlock a mutex.

Condition Variable Routines

int pthread_condattr_destroy(pthread_condattr_t *attr): Destroy a condition variable attributes object.
int pthread_condattr_init(pthread_condattr_t *attr): Initialize a condition variable attributes object with default values.
int pthread_cond_broadcast(pthread_cond_t *cond): Unblock all threads currently blocked on the specified condition variable.
int pthread_cond_destroy(pthread_cond_t *cond): Destroy a condition variable.
int pthread_cond_init(pthread_cond_t *cond, const pthread_condattr_t *attr): Initialize a condition variable with specified attributes.
int pthread_cond_signal(pthread_cond_t *cond): Unblock at least one of the threads blocked on the specified condition variable.
int pthread_cond_timedwait(pthread_cond_t *cond, pthread_mutex_t *mutex, const struct timespec *abstime);: Unlock the specified mutex, wait no longer than the specified time for a condition, and then relock the mutex.
int pthread_cond_wait(pthread_cond_t *, pthread_mutex_t *mutex): Unlock the specified mutex, wait for a condition, and relock the mutex.

Read/Write Lock Routines

int pthread_rwlock_destroy(pthread_rwlock_t *lock): Destroy a read/write lock object.
int pthread_rwlock_init(pthread_rwlock_t *lock, const pthread_rwlockattr_t *attr);: Initialize a read/write lock object.
int pthread_rwlock_rdlock(pthread_rwlock_t *lock): Lock a read/write lock for reading, blocking until the lock can be acquired.
int pthread_rwlock_tryrdlock(pthread_rwlock_t *lock): Attempt to lock a read/write lock for reading, without blocking if the lock is unavailable.
int pthread_rwlock_trywrlock(pthread_rwlock_t *lock): Attempt to lock a read/write lock for writing, without blocking if the lock is unavailable.
int pthread_rwlock_unlock(pthread_rwlock_t *lock): Unlock a read/write lock.
int pthread_rwlock_wrlock(pthread_rwlock_t *lock): Lock a read/write lock for writing, blocking until the lock can be acquired.
int pthread_rwlockattr_destroy(pthread_rwlockattr_t *attr): Destroy a read/write lock attribute object.
int pthread_rwlockattr_getpshared(const pthread_rwlockattr_t *attr, int *pshared);: Retrieve the process shared setting for the read/write lock attribute object.
int pthread_rwlockattr_init(pthread_rwlockattr_t *attr): Initialize a read/write lock attribute object.
int pthread_rwlockattr_setpshared(pthread_rwlockattr_t *attr, int pshared): Set the process shared setting for the read/write lock attribute object.

Per-Thread Context Routines

int pthread_key_create(pthread_key_t *key, void (*routine)(void *)): Create a thread-specific data key.
int pthread_key_delete(pthread_key_t key): Delete a thread-specific data key.
void * pthread_getspecific(pthread_key_t key): Get the thread-specific value for the specified key.
int pthread_setspecific(pthread_key_t key, const void *value_ptr): Set the thread-specific value for the specified key.

Cleanup Routines

int pthread_atfork(void (*prepare)(void), void (*parent)(void), void (*child)(void));: Register fork handlers.
void pthread_cleanup_pop(int execute): Remove the routine at the top of the calling thread's cancellation cleanup stack and optionally invoke it.
void pthread_cleanup_push(void (*routine)(void *), void *routine_arg): Push the specified cancellation cleanup handler onto the calling thread's cancellation stack.

INSTALLATION

The default system libraries include pthread functions. No additional libraries or CFLAGS are necessary to use these interfaces.

STANDARDS

The functions with the pthread_ prefix and not _np suffix or pthread_rwlock prefix conform to ISO/IEC 9945-1:1996 (“POSIX.1”).

The functions with the pthread_ prefix and _np suffix are non-portable extensions to POSIX threads.

The functions with the pthread_rwlock prefix are extensions created by The Open Group as part of the Version 2 of the Single UNIX Specification (“SUSv2”).