pthread_condattr_setpshared(3THR) sets the scope of a condition variable to either process private (intraprocess) or system wide (interprocess). If the condition variable is created with the pshared attribute set to the PTHREAD_PROCESS_SHARED state, and it exists in shared memory, it can be shared among threads from more than one process. This is equivalent to the USYNC_PROCESS flag in mutex_init() in the original Solaris threads.
If the mutex pshared attribute is set to PTHREAD_PROCESS_PRIVATE (default value), only those threads created by the same process can operate on the mutex. Using PTHREAD_PROCESS_PRIVATE results in the same behavior as with the USYNC_THREAD flag in the original Solaris threads cond_init() call, which is that of a local condition variable. PTHREAD_PROCESS_SHARED is equivalent to a global condition variable.
Prototype: 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);
pthread_condattr_setpshared() returns zero after completing successfully. Any other returned value indicates that an error occurred. If the following condition occurs, the function fails and returns the corresponding value.