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    <p>The proper way to handle problems inside akka actors is not to throw an exception but rather to set supervisor hierarchies </p> <blockquote> <p>"Throwing an exception in concurrent code (let’s assume we are using non-linked actors), will just simply blow up the thread that currently executes the actor.</p> <p>There is no way to find out that things went wrong (apart from inspecting the stack trace). There is nothing you can do about it."</p> </blockquote> <p>see <a href="http://akka.io/docs/akka/1.2/scala/fault-tolerance.html">Fault Tolerance Through Supervisor Hierarchies (1.2)</a></p> <p><strong>* note *</strong> the above is true for old versions of Akka (1.2) In newer versions (e.g. 2.2) you'd still set a supervisor hierarchy but it will trap Exceptions thrown by child processes. e.g.</p> <pre><code>class Child extends Actor { var state = 0 def receive = { case ex: Exception ⇒ throw ex case x: Int ⇒ state = x case "get" ⇒ sender ! state } } </code></pre> <p>and in the supervisor:</p> <pre><code>class Supervisor extends Actor { import akka.actor.OneForOneStrategy import akka.actor.SupervisorStrategy._ import scala.concurrent.duration._ override val supervisorStrategy = OneForOneStrategy(maxNrOfRetries = 10, withinTimeRange = 1 minute) { case _: ArithmeticException ⇒ Resume case _: NullPointerException ⇒ Restart case _: IllegalArgumentException ⇒ Stop case _: Exception ⇒ Escalate } def receive = { case p: Props ⇒ sender ! context.actorOf(p) } } </code></pre> <p>see <a href="http://doc.akka.io/docs/akka/2.2.1/scala/fault-tolerance.html">Fault Tolerance Through Supervisor Hierarchies (2.2)</a></p>
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    1. POAkka Actor not terminating if an exception is thrown
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    1. USArnon Rotem-Gal-Oz
    1. USArnon Rotem-Gal-Oz
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    1. COI had the same problem with exceptions: Thrown, displayed, but the actor processed further messages as if the exception hasn't occurred. So I switched to supervisor hierarchies. Exhausting to do so only because exceptions can't be handled otherwise.
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      1. USPeter Schmitz
    2. COThis doesn't appear to be true in [more recent versions of Akka](http://doc.akka.io/docs/akka/2.2.1/scala/fault-tolerance.html), where throwing exceptions is exactly what supervisors supervise.
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    3. COI updated the answer to current versions of Akka
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