Actor lifetime, concurrency, and consistency

The Dapr actor model relies on two main components: the Dapr runtime, operating in the sidecar, and the Dapr placement service.

Placement service

The placement service is responsible for keeping a map of the Dapr instances that are capable of serving actors. Considering our example, the reservationactor-service application is an example of such a service.

Once a new instance of our new reservationactor-service Dapr application starts, it informs the placement service that it is ready to serve actors of the ReservationItemActor type.

The placement service broadcasts a map – in the form of a hash table with the hosts' information and the served actor types – to all the Dapr sidecars operating in the environment.

Thanks to the host's map being constantly updated, actors are uniformly distributed over the actor service instances.

In the Kubernetes deployment mode of Dapr, the host is a Pod (a group of...