I am replacing a pthread threading implementation with a boost threads implementation so I can use the code on Windows. There is a ReadWriteMutex class that has the following declaration: class ReadWriteMutex { public: ReadWriteMutex(); virtual ~ReadWriteMutex() {} // these get the lock and block until it is done successfully virtual void acquireRead() const; virtual void acquireWrite() const; // these attempt to get the lock, returning false immediately if they fail virtual bool attemptRead() const; virtual bool attemptWrite() const; // this releases both read and write locks virtual void release() const; private: class impl; boost::shared_ptr<impl> impl_; }; Note the release() method that works for a thread that holds either the read or write lock. My implementation uses boost::shared_mutex. acquireRead calls lock_shared(), acquireWrite calls lock(), attemptRead calls try_lock_shared(), attemptWrite calls try_lock, and release calls ??????? AFAICT there is no equivalent to the pthread_rwlock_unlock() call that the original version of release() called. Am I missing something? Thanks, Rush