Akka: Printing list of actors

To print the list of actors that are running in the actor system, you can add following scheduler that will print actor path every 10 seconds:

import akka.actor.{Actor, ActorIdentity, ActorLogging, ActorRef, Cancellable, Props}

class TestActor extends Actor with ActorLogging {
  private var scheduler: Cancellable = _

  @scala.throws[Exception](classOf[Exception])
  override def preStart(): Unit = {
    import scala.concurrent.duration._

    scheduler = context.system.scheduler.schedule(
      initialDelay = 0 seconds,
      interval = 10 seconds,
      receiver = self,
      message = ActorIdentity("", Some(self))
    )
  }

  @scala.throws[IOException](classOf[IOException])
  override def postStop() = {
    scheduler.cancel
  }

  override def receive = {
    case ActorIdentity(_, Some(ref)) =>
      log.info(ref.path.toString)
  }
}