What is Akka Cluster Sharding, and how does it help in scaling the application?

Akka Cluster Sharding is a feature of the Akka toolkit that enables horizontal scaling of stateful actors across multiple nodes in an Akka cluster. It manages actor instances, distributing them evenly and ensuring fault tolerance by rebalancing and relocating actors when necessary.

Cluster sharding helps scale applications by :

1. Distributing load : Actors are spread across available nodes, reducing individual node workload.

2. Automatic rebalancing : As nodes join or leave, actors are redistributed to maintain balance.

3. Location transparency : Clients interact with actors without knowing their physical location.

4. Persistence : State changes can be persisted for recovery after failures or restarts.

5. Message routing : Messages are routed to appropriate shard regions, which locate target actors.

6. Passivation : Idle actors can be passivated to free up resources.