Applied Akka Patterns

Chapter 4. Good Actor Design

Understanding how to build good actor systems begins at the small scale. The large-scale structures that we build are often the source of our greatest successes or failures in any software project, regardless of whether it uses Akka. But if we don’t first understand the smaller building blocks that go into those larger structures, we run the risk of small mistakes propagating throughout the system in a way that makes the code unmaintainable. This problem isn’t unique to Akka. If you try to write code using a functional language without first understanding the basics of functional programming, you will run into similar problems.

In this chapter, we talk about how to avoid such issues and apply good principles and practices to building your actors and your system.

Starting Small

As just mentioned, understanding how to build good actor systems must begin at the small scale. We can talk about how to build and connect large-scale actor constructs together, but if we lack a good design at the small scale, we can still easily end up with bottlenecks, blocking operations, and spaghetti code that can cause the application to fail.

The most common mistakes people make when working with Akka happen in the small scale rather than the large end of the spectrum. Even though these problems tend to be smaller in scope than architectural problems, when compounded together they can become significant. Whether it is accidentally exposing mutable state, or closing over ...