Since Actors are single-threaded, they can process only one request at a time. This means that requests to the same Actor instance need to wait for the previous request to get processed. Turn based concurrency ensures that no other Actor methods or timer/reminder callbacks will be in progress until this callback completes execution.

Actors can deadlock on each other if there is a circular request between two Actors while an external request is made to one of the Actors simultaneously. The Actor runtime will automatically time out on Actor calls and throw an exception to the caller to interrupt possible deadlock situations: