scala - Call Method every x seconds -

I am using Scala and Play frameworks and I am trying to execute a method every 20 seconds.

The code I use is:

  val system = akka.actor.ActorSystem ("system") system.scheduler.schedule (0 seconds, 30 seconds (Worker ())  

It starts working, but after about 20 minutes this worker prevents the call from the law. What is the problem?