how to implement multi threads in akka & scala?

Question

Now I wanna an actor to send messages to other actors and at the same time receive messages from others. It seems I need use multi threads in Akka. Below is my code:

def receive = {
    case Rumor => {     
        count+=1; 
            if ...
            else self ! Sleep(FiniteDuration(20, "millis"))
    }
    case Sleep(duration) => {
        case object WakeUp
        context.system.scheduler.scheduleOnce(duration, self, WakeUp)
        context.become(
        {
            case WakeUp => context.unbecome()
                           others ! Rumor
        }, discardOld = false   
        )
    }       
    case _=> .....
 }

my problem are:

1) I am not sure my code would work as I expect. Reference use Akka scheduler inside an actor

2) I already import

import scala.math._
import akka.actor._
import scala.util.Random
import scala.concurrent.duration._

but the compiler still reports error on:

error: Cannot find an implicit ExecutionContext, either require one yourself or import ExecutionContext.Implicits.global
        context.system.scheduler.scheduleOnce(duration, self, WakeUp)

Asking I want actor to send messages to other actors and at the same time receive messages from others is the same as How can I shoot myself in the leg. You're exchanging every point of actor model for a huge pile of problems. Scala isn't built to be actors only (like Erlang was) so if you really need to use plain-old-java-concurrency with bare threads and whistles, use it. — om-nom-nom
– om-nom-nom, Commented Oct 4, 2013 at 8:20

Vladimir Matveev · Accepted Answer · 2013-10-04 05:43:37Z

20

You're doing the whole thing wrong. Actors are designed specifically to remove most problems caused by manual thread management. One of the features for this is that actors always work sequentially. You cannot force an actor to process more than one message at a time. Akka even provides several guarantees about messages and their order. This allows complete thread safety, if you don't do anything stupid, like using mutable messages or calling other actor objects directly.

Sure, you can run different actors in separate threads (using correct dispatcher), and they really will process their messages in parallel. But you cannot run single actor from multiple threads, whatever you do.

You should really read excellent Akka documentation, especial its section on general concepts. You won't have questions like this if you read and understand it.

answered Oct 4, 2013 at 5:43

Vladimir Matveev

129k35 gold badges310 silver badges308 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

egprentice · Accepted Answer · 2013-10-04 01:51:23Z

0

Try importing ExecutionContext.Implicits.global

answered Oct 4, 2013 at 1:51

egprentice

8247 silver badges15 bronze badges

1 Comment

city Over a year ago

it does not work. But I add "import context.dispatcher", it works. Now my problem is this method can not work as I expect. Do you have any idea? Thanks

Wolfgang Grinfeld · Accepted Answer · 2015-08-25 11:06:30Z

0

Use a Router: e.g.

val router1 = system.actorOf(Props[SomeMultiThreadActorClass].withRouter(RoundRobinRouter(nrOfInstances = 5)))

Consider separate application domains (if your platform allows for it) to avoid one thread adversely affecting another one.

answered Aug 25, 2015 at 11:06

Wolfgang Grinfeld

3993 silver badges3 bronze badges

Collectives™ on Stack Overflow

how to implement multi threads in akka & scala?

3 Answers 3

Comments

1 Comment

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Related