Digital

NAME

pthread_lock_global_np − Locks the global mutex. If the global mutex is held by another thread, this routine causes the thread to wait for the global mutex to become available. 

SYNOPSIS

#include <pthread.h>
void pthread_lock_global_np( );

PARAMETERS

None. 

DESCRIPTION

This routine locks the global mutex. If the global mutex is currently held by another thread when a thread calls this routine, the thread waits for the global mutex to become available. 

The thread that has locked the global mutex becomes its current owner and remains the owner until the same thread has unlocked it. This routine returns with the global mutex in the locked state and with the current thread as the global mutex’s current owner. 

Use the global mutex when calling a library package that is designed to run in a multithreaded environment. (Unless the documentation for a library function specifically states that it is compatible with multithreading, assume that it is not compatible; in other words, assume it is nonreentrant.) 

The global mutex is one lock. Any code that calls any function that is not known to be reentrant uses the same lock. This prevents dependencies among threads calling library functions and those functions calling other functions, and so on. 

The global mutex is a recursive mutex. A thread that has locked the global mutex can relock it without deadlocking. (The locking thread must call pthread_unlock_global_np as many times as it called this routine to allow another thread to lock the global mutex.) 

RETURN VALUES

None. 

RELATED INFORMATION

pthread_mutexattr_setkind_np(3), pthread_mutex_lock(3), pthread_mutex_unlock(3), pthread_unlock_global_np(3)