Setting the Scope of a Condition Variable

pthread_condattr_setpshared(3C) sets the scope of a condition variable to either process private (intraprocess) or system wide (interprocess).

pthread_condattr_setpshared Syntax

int pthread_condattr_setpshared(pthread_condattr_t *cattr, int pshared);

#include <pthread.h> 
pthread_condattr_t cattr; 
int ret; 

/* all processes */ 
ret = pthread_condattr_setpshared(&cattr, PTHREAD_PROCESS_SHARED); 

/* within a process */ 
ret = pthread_condattr_setpshared(&cattr, PTHREAD_PROCESS_PRIVATE);

A condition variable created with the pshared attribute set in shared memory to PTHREAD_PROCESS_SHARED, can be shared among threads from more than one process.

If the mutex pshared attribute is set to PTHREAD_PROCESS_PRIVATE, only those threads created by the same process can operate on the mutex. PTHREAD_PROCESS_PRIVATE is the default value. PTHREAD_PROCESS_PRIVATE behaves like a local condition variable. The behavior of PTHREAD_PROCESS_SHARED is equivalent to a global condition variable.

pthread_condattr_setpshared Return Values

pthread_condattr_setpshared() returns zero after completing successfully. Any other return value indicates that an error occurred. If the following condition occurs, the function fails and returns the corresponding value.

EINVAL

Description:

The value of cattr is invalid, or the pshared value is invalid.