When could Futures be more appropriate than Actors (or vice versa) in Scala?

Question

Suppose I need to run a few concurrent tasks.

I can wrap each task in a Future and wait for their completion. Alternatively I can create an Actor for each task. Each Actor would execute its task (e.g. upon receiving a "start" message) and send the result back.

I wonder when I should use the former (with Futures) and the latter (with Actors) approach and why the Future approach is considered better for the case described above.

Answer 1

Because it is syntactically simpler.

val tasks: Seq[() => T] = ???
val futures = tasks map {
  t => future { t() }
}
val results: Future[Seq[T]] = Future.sequence(futures)

The results future you can then wait on using Await.result or you can map it further/use it in for-comprehension or install callbacks on it.

Compare that to instantiating all the actors, sending messages to them, coding their receive blocks, receiving responses from them and shutting them down -- that would generally require more boilerplate.

Answer 2

I tend to think that actors are useful when you have interacting threads. In your case, it appears to be that all the jobs are independent; I would use futures.