C & C++ odo: Atomic Counters from the Command Line I couldn't think of a command-line program to increment a counter in a file without race conditions, at least not without some sort of database.
Ruby Making Refs in Ruby Using Celluloid Actors An example of using Celluloid Actors to provide a poor man's Ref (Clojure-like) around an immutable data structure in JRuby to protect shared state.
jRuby Preventing JRuby Concurrency Errors with Hamster How using Hamster's efficient, immutable, thread-safe collections can prevent ConcurrencyError exceptions in JRuby.
