Kilim: Isolation-typed actors for Java - A million actors, safe zero-copy communication

Abstract

This paper describes Kilim, a framework that employs a combination of techniques to help create robust, massively concurrent systems in mainstream languages such as Java: (i) ultra-lightweight, cooperatively-scheduled threads (actors), (ii) a message-passing framework (no shared memory, no locks) and (iii) isolation-aware messaging. Isolation is achieved by controlling the shape and ownership of mutable messages - they must not have internal aliases and can only be owned by a single actor at a time. We demonstrate a static analysis built around isolation type qualifiers to enforce these constraints. Kilim comfortably scales to handle hundreds of thousands of actors and messages on modest hardware. It is fast as well - task-switching is 1000x faster than Java threads and 60x faster than other lightweight tasking frameworks, and message-passing is 3x faster than Erlang (currently the gold standard for concurrency-oriented programming). © 2008 Springer-Verlag.