Cluster Sharding
Akka Cluster Sharding is a helper module that automatically distributes actors across multiple cluster nodes. These actors have an identifier and they are commonly known as entities. Each actor entity runs only at one location, and you can interact with them through the ClusterSharding extension. A shard is a group of entities that is managed together through an EntityId.
Cluster Sharding takes care of routing the message to the expected destination, so you don't need to know where the actors are running. It needs a persistent store to store actor information. We will configure our app to use the distributed data store, which will be the default as of Akka 2.5.0. We will learn more about distributed data in the next recipe.
Cluster Sharding is used when you have stateful actors where the size of the state does not fit the memory of a single machine. We can easily scale an application beyond a single machine, thanks to Cluster Sharding.
In this recipe, we are going to test this...
