How much processing should be done in an Akka actor ?

Question

I've to do some processing (run some jobs) on a regular interval (10min, 30min, 60min ...). I've different actors for each. I'm sending messages to self inside an actor to trigger the processing. The processing done inside an actor could take anywhere from a 10ms to 30s or more in some cases. My question from an Actor design perspective is how "heavy" can the processing inside an Actor receive be ? Or it doesn't really matter ?

Answer 1

It's fine to have actors that take arbitrarily long to process a message. But you wouldn't want to do that in an actor that is responsible for the timely processing of further messages.

A common pattern is to have a manager actor that receives messages and farms out work to worker actors. It's no problem if the worker actors take a long time, because the manager actor can simply create another worker actor if it needs one.

Think about what needs to be responsive and what will take a long time, and make sure a given actor isn't doing both.

But also, if you have something to do that is going to take 30 seconds, you might want to break it up into multiple actors somehow so that multiple cores can work on it in parallel. Another common pattern is for an actor given a task to look at how big it is and if it is over some threshold, spawn multiple actors and give each part of the job. Each of those actors then does the same thing, deciding whether to do the job itself or split up the work among some child actors. In this way trees of actors are formed on the fly based on the size of the job, and when the job is done the actors disappear.