Software transactional memory

I've never heard about such thing as STM, which is quite an interesting concurrency control concept, an alternative to more commonly used lock-based synchronization. It's usage could be found in Clojure programming language running under JVM, which I think makes both of these worth trying.

Though, it can't replace locking completely, well... because in fact it provides no locking :) So, some inconsistent states are still possible, therefore transaction locking should be used, which returns us back to Earth.