ReducerCommand

This actor performs the reduce operation on the received sequence of W objects, resulting in (ideally) a V2 object. It handles a Reduce command combining both the current K2 key and the sequence ws of W objects. The reply is a ReduceResult[K2,V2].

Note that logging the actual values received in the incoming message can be VERY verbose. It is therefore recommended practice to log the values as they pass through the reducer function (g) which is under the control of the application.