A CSP Model for Java Multithreading

Java threads are synchronised through primitives based upon monitor concepts developed in the early 1970s. The semantics of Java's primitives have only been presented in natural language - this paper remedies this with a simple and formal CSP model. In view of the difficulties encountered in reasoning about any non-trivial interactions between Java threads, being able to perform that reasoning in a formal context (where careless errors can be highlighted by mechanical checks) should be a considerable confidence boost. Further automated model-checking tools can be used to root out dangerous states (such as deadlock and livelock), find overlooked race hazards and prove equivalence between algorithms (e.g. between optimised and un-optimised versions). A case study using the CSP model to prove the correctness of the JCSP channel implementation (which is built in terms of standard Java monitor synchronisations) is presented.