Programming Concurrency on the JVM

Recap

Actors are single-threaded and communicate with each other by passing messages.

We learned that actors do the following:

• Make it easy to work with isolated mutability

• Eliminate synchronization concerns at its root

• Provide efficient one-way messaging but also provide the less efficient send-and-wait facility

• Are very scalable; while being single-threaded, they efficiently share a pool of threads

• Allow us to send messages but also provide typed versions (in Akka) backed by interfaces

• Allow us to coordinate with other actors using transactions

Although actors provide a powerful model, they also have limitations. There is potential for actor starvation and also deadlock if we’re not careful in designing with them. Also, we have to ensure that ...