title: Why does cancelling my running akka quickstart example app throw a java error?
body: <p>When I hit control-C to cancel my running akka quickstart app I get the following error.
  Is this normal or is there an akka config that can avoid this?</p>
  
  <p>Can someone explain why this occurs?</p>
  
  <pre><code>sbt:akka-quickstart-scala&gt; exit
  [info] shutting down sbt server
  [warn] Run canceled.
  Exception in thread "sbt-bg-threads-1" java.util.concurrent.RejectedExecutionException
      at java.util.concurrent.ForkJoinPool.externalSubmit(ForkJoinPool.java:2328)
      at java.util.concurrent.ForkJoinPool.externalPush(ForkJoinPool.java:2419)
      at java.util.concurrent.ForkJoinPool.execute(ForkJoinPool.java:2648)
      at scala.concurrent.impl.ExecutionContextImpl.execute(ExecutionContextImpl.scala:24)
      at sbt.internal.BackgroundThreadPool$BackgroundRunnable.$anonfun$cleanup$1(DefaultBackgroundJobService.scala:390)
      at sbt.internal.BackgroundThreadPool$BackgroundRunnable.$anonfun$cleanup$1$adapted(DefaultBackgroundJobService.scala:389)
      at scala.collection.immutable.List.foreach(List.scala:392)
      at sbt.internal.BackgroundThreadPool$BackgroundRunnable.cleanup(DefaultBackgroundJobService.scala:389)
      at sbt.internal.BackgroundThreadPool$BackgroundRunnable.run(DefaultBackgroundJobService.scala:359)
      at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
      at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
      at java.lang.Thread.run(Thread.java:745)
  </code></pre>