Composable Memory Transactions
I've been doing a little bit of research into different ways of handling atomic operations on data in the face of concurrent threads of execution. The standard mutex/semaphore model is fraught with opportunities for programmer error and is difficult to reason about. It also becomes very unwieldy when composition of atomic operations is necessary. A possible solution is to use transactional memory and optimistic synchronization instead of mutexes. There's a good description of how this works in the paper Composable Memory Transactions. There's also an implementation of Optimistic Concurrency in Scheme48.