fix some more comments and make Router dispatcher configurable

- assert locking balance when using Unsafe.instance.monitorExit
- add RouterConfig.routerDispatcher
- re-enable “busy” resizer test after switching to BalancingDispatcher
- document resizer asynchronicity and how to configure dispatchers

akka-docs/scala/code/akka/docs/routing/RouterDocSpec.scala

@@ -0,0 +1,29 @@
+/**
+ * Copyright (C) 2009-2012 Typesafe Inc. <http://www.typesafe.com>
+ */
+package akka.docs.routing
+
+import RouterDocSpec.MyActor
+import akka.actor.{ Props, Actor }
+import akka.testkit.AkkaSpec
+import akka.routing.RoundRobinRouter
+
+object RouterDocSpec {
+  class MyActor extends Actor {
+    def receive = {
+      case _ ⇒
+    }
+  }
+}
+
+class RouterDocSpec extends AkkaSpec {
+
+  import RouterDocSpec._
+
+  //#dispatchers
+  val router = system.actorOf(Props[MyActor]
+    .withRouter(RoundRobinRouter(5, routerDispatcher = "router")) // “head” will run on "router" dispatcher
+    .withDispatcher("workers")) // MyActor workers will run on "workers" dispatcher
+  //#dispatchers
+
+}