It's Actors All The Way Down

2021-06-08 EDIT: Added serializer implementation using only the actor message-event queue. One of the earliest concepts explored on this blog was the Serializer, which is a mechanism for providing exclusive access to a group of actors [1]. More recently, Carl Hewitt has referred to an extended version of this mechanism (with holes) as “Swiss Cheese”. […]

Mutable shared state is the root of all evil in concurrent systems. The history of concurrent computation is a basically the story of approaches to managing mutable shared state. The thread model, which has long held the dominant position, leads to intractable complexity [1]. The actor model captures state in the behavior of an actor. […]

In part 6 of our series implementing programming language constructs with actors, we explore meta-circular definition of imperative actor primitives. We have now moved beyond expressions which yield values, and focus on statements which cause effects. The constructs explored here are the heart of any actor-based system. In order to support actor primitive statements, our […]

A significant challenge in developing concurrent systems is the problem of composability. We create a solution that works properly in isolation, but when composed with other solutions leads to interference. The actor model ensures that individual actors may be composed without changing their behavior. Interference is prevented by definition, keeping the system consistent. In order […]