Scala Reactive Programming

Prefer tell over ask with Akka Actors

As we know, we can use one of the following two approaches to send messages between Akka Actors:

• Tell (!): It works in Fire-and-Forget fashion. Its a non-blocking and asynchronous approach.
• Ask (?): It works in Send-And-Receive-Future fashion. It sends a message asynchronously and returns a Future representing a possible result.

There are performance implications of using ask since something needs to keep track of when it times out, there needs to be something that bridges a Promise into an ActorRef and it also needs to be reachable through remoting. So always prefer tell for performance, and only ask if you must.

For more information refer to the Akka Toolkit documentation at https://doc.akka.io/docs/akka/current//actors.html#send-messages ...