clarify need to carefully managing blocking, see #2616

akka-docs/rst/scala/code/docs/dispatcher/DispatcherDocSpec.scala

@@ -186,6 +186,13 @@ class DispatcherDocSpec extends AkkaSpec(DispatcherDocSpec.config) {
     //#defining-pinned-dispatcher
   }
 
+  "looking up a dispatcher" in {
+    //#lookup
+    // for use with Futures, Scheduler, etc.
+    implicit val executionContext = system.dispatchers.lookup("my-dispatcher")
+    //#lookup
+  }
+
   "defining priority dispatcher" in {
     //#prio-dispatcher
 

akka-docs/rst/scala/dispatchers.rst

@@ -13,6 +13,15 @@ Default dispatcher
 Every ``ActorSystem`` will have a default dispatcher that will be used in case nothing else is configured for an ``Actor``.
 The default dispatcher can be configured, and is by default a ``Dispatcher`` with a "fork-join-executor", which gives excellent performance in most cases.
 
+.. _dispatcher-lookup-scala:
+
+Looking up a Dispatcher
+-----------------------
+
+Dispatchers implement the :class:`ExecutionContext` interface and can thus be used to run :class:`Future` invocations etc.
+
+.. includecode:: code/docs/dispatcher/DispatcherDocSpec.scala#lookup
+
 Setting the dispatcher for an Actor
 -----------------------------------