scala actor blocking current thread

Question

I tried to implement a timer based on Scala's actors API with, the current Thread actor (Actor.self) as the timer and an anonymous Actor which does the work that needs to be completed in time. I have the following Scala program ``` import scala.actors.Actor.self import scala.actors.TIMEOUT object Main { def main(args: Array[String]): Unit = { val thiz = self actor { // do heavy work here thiz ! "finish" } self.reactWithin(1000) { case "finish" => println("complete") case TIMEOUT => println("timeout") } } } ``` When I run the program, I received ``` Exception in thread "main" scala.actors.SuspendActorControl scala.actors.ActorProxy@1d99a4d: caught java.lang.InterruptedException ``` Please show me the way to overcome the problem.

Accepted Answer

You have two types of control passing with scala-actors, thread-blocking or thread-suspension. the latter means a control exception is thrown (the thread is made available again to the thread pool manager), and the actor body re-executed when a message comes into its mailbox. See the actors tutorial for more details, esp. section "Make it Thread-less!".

The `receiveWithin` method uses the thread-blocking, and the `reactWithin` the suspension. The problem you have here is that there is no outer managing actor that catches the exception. This only works within a "proper" actor, not with the proxy created for the main thread. So if you want to wait on the main thread outside an explicit actor, you need to use thread blocking / `receiveWithin`:

```
self.receiveWithin(1000) { ... }
```

scala actor blocking current thread

Solution

Problem