In a simple app, I create a basic ActorSystem with the remote provider configured. Let's say I start my app once again so that the second run should fail as the remote connection listener port is already in use. I can see the related exception being thrown as expected, however, the background services (e.g. fork-join pool, I/O channel threads) started earlier are not cleaned up after the failure.
In the below simple example, the main thread dies due to the exception but the JVM keeps running as the stuck-in (and thus invalid) background services. You can see a thread dump in the attachment.

Example code:

import akka.actor.ActorSystem

object RemoteFail {
  def start() = {
    val system = ActorSystem("system")
    println("foo")
  }

  def main(args: Array[String]) = {
    start()
    println("bar")
  }
}

Example config:

akka {
  actor {
    provider = "akka.remote.RemoteActorRefProvider"
  }
  remote {
    transport = "akka.remote.netty.NettyRemoteTransport"
    netty.tcp {
      hostname = "127.0.0.1"
      port = 2552
    }
  }
}

Used environment:

• Windows 8
• JDK 1.7 64-bit
• Scala 2.10
• Akka 2.3.0