Multithreaded Programming Guide

Try to Acquire a Write Lock


#include <synch.h>  (or #include <thread.h>)

int rw_trywrlock(rwlock_t *rwlp);

Use rw_trywrlock(3T) to attempt to acquire a write lock on the read-write lock pointed to by rwlp. When the read-write lock is already locked for reading or writing, it returns an error. (For POSIX threads, see "pthread_rwlock_trywrlock(3T)".)

Return Values

rw_trywrlock() returns zero after completing successfully. Any other returned value indicates that an error occurred. When any of the following conditions occur, the function fails and returns the corresponding value.


Invalid argument.


rwlp points to an illegal address.


The read-write lock pointed to by rwlp was already locked.