Removing receiver from Envelope and switch to use the Mailbox.actor instead, this should speed up the BalancingDispatcher by some since it doesn't entail any allocations in adopting a message

akka-actor-tests/src/test/scala/akka/actor/dispatch/ActorModelSpec.scala

@@ -127,10 +127,10 @@ object ActorModelSpec {
       super.unregister(actor)
     }
 
-    protected[akka] abstract override def dispatch(invocation: Envelope) {
+    protected[akka] abstract override def dispatch(receiver: ActorCell, invocation: Envelope) {
-      val stats = getStats(invocation.receiver.self)
+      val stats = getStats(receiver.self)
       stats.msgsReceived.incrementAndGet()
-      super.dispatch(invocation)
+      super.dispatch(receiver, invocation)
     }
 
     protected[akka] abstract override def start() {

akka-actor-tests/src/test/scala/akka/dispatch/MailboxConfigSpec.scala

@@ -80,12 +80,7 @@ abstract class MailboxSpec extends AkkaSpec with BeforeAndAfterAll with BeforeAn
     result
   }
 
-  def createMessageInvocation(msg: Any): Envelope = {
+  def createMessageInvocation(msg: Any): Envelope = Envelope(msg, NullChannel)
-    new Envelope(
-      actorOf(new Actor { //Dummy actor
-        def receive = { case _ ⇒ }
-      }).asInstanceOf[LocalActorRef].underlying, msg, NullChannel)
-  }
 
   def ensureInitialMailboxState(config: MailboxType, q: Mailbox) {
     q must not be null

akka-actor/src/main/scala/akka/actor/ActorCell.scala

@@ -278,7 +278,7 @@ private[akka] class ActorCell(
   //TODO FIXME remove this method
   def supervisor: Option[ActorRef] = props.supervisor
 
-  def postMessageToMailbox(message: Any, channel: UntypedChannel): Unit = dispatcher dispatch Envelope(this, message, channel)
+  def postMessageToMailbox(message: Any, channel: UntypedChannel): Unit = dispatcher.dispatch(this, Envelope(message, channel))
 
   def postMessageToMailboxAndCreateFutureResultWithTimeout(
     message: Any,
@@ -288,7 +288,7 @@ private[akka] class ActorCell(
       case f: ActorPromise ⇒ f
       case _               ⇒ new ActorPromise(timeout)(dispatcher)
     }
-    dispatcher dispatch Envelope(this, message, future)
+    dispatcher.dispatch(this, Envelope(message, future))
     future
   }
 

akka-actor/src/main/scala/akka/dispatch/AbstractDispatcher.scala

@@ -17,13 +17,7 @@ import scala.annotation.tailrec
 /**
  * @author <a href="http://jonasboner.com">Jonas Bon&#233;r</a>
  */
-final case class Envelope(val receiver: ActorCell, val message: Any, val channel: UntypedChannel) {
+final case class Envelope(val message: Any, val channel: UntypedChannel)
-  if (receiver eq null) throw new IllegalArgumentException("Receiver can't be null")
-
-  final def invoke() {
-    receiver invoke this
-  }
-}
 
 object SystemMessage {
   @tailrec
@@ -295,7 +289,7 @@ abstract class MessageDispatcher(val app: AkkaApplication) extends Serializable
   /**
    *   Will be called when the dispatcher is to queue an invocation for execution
    */
-  protected[akka] def dispatch(invocation: Envelope)
+  protected[akka] def dispatch(receiver: ActorCell, invocation: Envelope)
 
   /**
    * Suggest to register the provided mailbox for execution

akka-actor/src/main/scala/akka/dispatch/BalancingDispatcher.scala

@@ -57,12 +57,7 @@ class BalancingDispatcher(
   class SharingMailbox(_actor: ActorCell) extends Mailbox(_actor) with DefaultSystemMessageQueue {
     final def enqueue(handle: Envelope) = messageQueue.enqueue(handle)
 
-    final def dequeue(): Envelope = {
+    final def dequeue(): Envelope = messageQueue.dequeue()
-      val envelope = messageQueue.dequeue()
-      if (envelope eq null) null
-      else if (envelope.receiver eq actor) envelope
-      else envelope.copy(receiver = actor)
-    }
 
     final def numberOfMessages: Int = messageQueue.numberOfMessages
 
@@ -106,8 +101,7 @@ class BalancingDispatcher(
     } else true
   }
 
-  override protected[akka] def dispatch(invocation: Envelope) = {
+  override protected[akka] def dispatch(receiver: ActorCell, invocation: Envelope) = {
-    val receiver = invocation.receiver
     messageQueue enqueue invocation
 
     val buddy = buddies.pollFirst()

akka-actor/src/main/scala/akka/dispatch/Dispatcher.scala

@@ -78,8 +78,8 @@ class Dispatcher(
   protected[akka] val executorServiceFactory = executorServiceFactoryProvider.createExecutorServiceFactory(name)
   protected[akka] val executorService = new AtomicReference[ExecutorService](new LazyExecutorServiceWrapper(executorServiceFactory.createExecutorService))
 
-  protected[akka] def dispatch(invocation: Envelope) = {
+  protected[akka] def dispatch(receiver: ActorCell, invocation: Envelope) = {
-    val mbox = invocation.receiver.mailbox
+    val mbox = receiver.mailbox
     mbox enqueue invocation
     registerForExecution(mbox, true, false)
   }

akka-actor/src/main/scala/akka/dispatch/Mailbox.scala

@@ -170,7 +170,7 @@ abstract class Mailbox(val actor: ActorCell) extends AbstractMailbox with Messag
           var processedMessages = 0
           val deadlineNs = if (dispatcher.isThroughputDeadlineTimeDefined) System.nanoTime + TimeUnit.MILLISECONDS.toNanos(dispatcher.throughputDeadlineTime) else 0
           do {
-            nextMessage.invoke
+            actor invoke nextMessage
 
             processAllSystemMessages() //After we're done, process all system messages
 
@@ -182,7 +182,7 @@ abstract class Mailbox(val actor: ActorCell) extends AbstractMailbox with Messag
             } else null //Abort
           } while (nextMessage ne null)
         } else { //If we only run one message per process
-          nextMessage.invoke //Just run it
+          actor invoke nextMessage //Just run it
           processAllSystemMessages() //After we're done, process all system messages
         }
       }

akka-remote/src/main/scala/akka/serialization/SerializationProtocol.scala

@@ -101,7 +101,7 @@ class ActorSerialization(val app: AkkaApplication, remote: RemoteSupport) {
 
             l map { m ⇒
               remoteActorSerialization.createRemoteMessageProtocolBuilder(
-                Option(m.receiver.self),
+                localRef,
                 Left(actorRef.uuid),
                 actorRef.address,
                 app.AkkaConfig.ActorTimeoutMillis,

akka-testkit/src/main/scala/akka/testkit/CallingThreadDispatcher.scala

@@ -150,20 +150,20 @@ class CallingThreadDispatcher(_app: AkkaApplication, val name: String = "calling
     }
   }
 
-  protected[akka] override def dispatch(handle: Envelope) {
+  protected[akka] override def dispatch(receiver: ActorCell, handle: Envelope) {
-    val mbox = getMailbox(handle.receiver)
+    val mbox = getMailbox(receiver)
     val queue = mbox.queue
     val execute = mbox.suspendSwitch.fold {
       queue.push(handle)
       if (warnings && handle.channel.isInstanceOf[Promise[_]]) {
-        app.eventHandler.warning(this, "suspendSwitch, creating Future could deadlock; target: %s" format handle.receiver)
+        app.eventHandler.warning(this, "suspendSwitch, creating Future could deadlock; target: %s" format receiver)
       }
       false
     } {
       queue.push(handle)
       if (queue.isActive) {
         if (warnings && handle.channel.isInstanceOf[Promise[_]]) {
-          app.eventHandler.warning(this, "blocked on this thread, creating Future could deadlock; target: %s" format handle.receiver)
+          app.eventHandler.warning(this, "blocked on this thread, creating Future could deadlock; target: %s" format receiver)
         }
         false
       } else {
@@ -200,10 +200,10 @@ class CallingThreadDispatcher(_app: AkkaApplication, val name: String = "calling
       }
       if (handle ne null) {
         try {
-          handle.invoke
+          mbox.actor.invoke(handle)
           if (warnings) handle.channel match {
             case f: ActorPromise if !f.isCompleted ⇒
-              app.eventHandler.warning(this, "calling %s with message %s did not reply as expected, might deadlock" format (handle.receiver, handle.message))
+              app.eventHandler.warning(this, "calling %s with message %s did not reply as expected, might deadlock" format (mbox.actor, handle.message))
             case _ ⇒
           }
           true