Programming Concurrency on the JVM

Limitations of the Actor-Based Model

The actor-based model makes it easy to program with isolated mutability, but it does have some limitations.

Actors communicate with each other through messages. In languages that do not enforce immutability, we must be very careful to ensure the messages are immutable. Passing mutable messages can lead to thread-safety concerns and eventually the perils of shared mutability. Tools may evolve to verify that the messages are immutable; until then, the onus is on us to ensure immutability.

Actors run asynchronously but coordinate by passing messages. The unexpected failure of actors may result in starvation—one or more actors may be waiting for messages that would never arrive because of the failure. We must ...