Domains: safe sharing among actors

The actor model has already proven itself as an interesting concurrency model that avoids issues such as deadlocks and race conditions by construction, and thus facilitates concurrent programming. While it has mainly been used in a distributed context it is certainly equally useful for modeling interactive components in a concurrent setting. In component based software, the actor model lends itself to naturally dividing the components over different actors and using message passing concurrency for implementing the interactivity between these components. The tradeoff is that the actor model sacrifices expressiveness and efficiency especially with respect to parallel access to shared state.

This paper gives an overview of the disadvantages of the actor model in the case of shared state and then formulates an extension of the actor model to solve these issues. Our solution proposes domains and synchronization views to solve the issues without compromising on the semantic properties of the actor model. Thus, the resulting concurrency model maintains deadlock-freedom and avoids low-level race conditions.