Roland found a nasty race between activate in supervisor and locally, this commit should fix it, and rename activate to point

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

@@ -361,10 +361,10 @@ private[akka] class ActorCell(
             case null                  ⇒ faultResume(inRespToFailure)
             case w: WaitingForChildren ⇒ w.enqueue(message)
           }
-        case Terminate()            ⇒ terminate()
-        case Supervise(child, uid)  ⇒ supervise(child, uid)
-        case ChildTerminated(child) ⇒ todo = handleChildTerminated(child)
-        case NoMessage              ⇒ // only here to suppress warning
+        case Terminate()                  ⇒ terminate()
+        case Supervise(child, async, uid) ⇒ supervise(child, async, uid)
+        case ChildTerminated(child)       ⇒ todo = handleChildTerminated(child)
+        case NoMessage                    ⇒ // only here to suppress warning
       }
     } catch {
       case e @ (_: InterruptedException | NonFatal(_)) ⇒ handleInvokeFailure(Nil, e, "error while processing " + message)
@@ -492,21 +492,21 @@ private[akka] class ActorCell(
         }
     }
 
-  private def supervise(child: ActorRef, uid: Int): Unit = if (!isTerminating) {
+  private def supervise(child: ActorRef, async: Boolean, uid: Int): Unit = if (!isTerminating) {
     // Supervise is the first thing we get from a new child, so store away the UID for later use in handleFailure()
     initChild(child) match {
       case Some(crs) ⇒
         crs.uid = uid
-        handleSupervise(child)
+        handleSupervise(child, async)
         if (system.settings.DebugLifecycle) publish(Debug(self.path.toString, clazz(actor), "now supervising " + child))
       case None ⇒ publish(Error(self.path.toString, clazz(actor), "received Supervise from unregistered child " + child + ", this will not end well"))
     }
   }
 
   // future extension point
-  protected def handleSupervise(child: ActorRef): Unit = child match {
-    case r: RepointableActorRef ⇒ r.activate()
-    case _                      ⇒
+  protected def handleSupervise(child: ActorRef, async: Boolean): Unit = child match {
+    case r: RepointableActorRef if async ⇒ r.point()
+    case _                               ⇒
   }
 
   final protected def clearActorFields(actorInstance: Actor): Unit = {

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

@@ -381,7 +381,7 @@ class LocalActorRefProvider(
 
     override def sendSystemMessage(message: SystemMessage): Unit = stopped ifOff {
       message match {
-        case Supervise(_, _)    ⇒ // TODO register child in some map to keep track of it and enable shutdown after all dead
+        case Supervise(_, _, _) ⇒ // TODO register child in some map to keep track of it and enable shutdown after all dead
         case ChildTerminated(_) ⇒ stop()
         case _                  ⇒ log.error(this + " received unexpected system message [" + message + "]")
       }
@@ -585,14 +585,13 @@ class LocalActorRefProvider(
         if (settings.DebugRouterMisconfiguration && deployer.lookup(path).isDefined)
           log.warning("Configuration says that {} should be a router, but code disagrees. Remove the config or add a routerConfig to its Props.")
 
-        if (async) new RepointableActorRef(system, props, supervisor, path).initialize()
+        if (async) new RepointableActorRef(system, props, supervisor, path).initialize(async)
         else new LocalActorRef(system, props, supervisor, path)
       case router ⇒
         val lookup = if (lookupDeploy) deployer.lookup(path) else None
         val fromProps = Iterator(props.deploy.copy(routerConfig = props.deploy.routerConfig withFallback router))
         val d = fromProps ++ deploy.iterator ++ lookup.iterator reduce ((a, b) ⇒ b withFallback a)
-        val ref = new RoutedActorRef(system, props.withRouter(d.routerConfig), supervisor, path).initialize()
-        if (async) ref else ref.activate()
+        new RoutedActorRef(system, props.withRouter(d.routerConfig), supervisor, path).initialize(async)
     }
   }
 

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

@@ -53,14 +53,15 @@ private[akka] class RepointableActorRef(
    *
    * This is protected so that others can have different initialization.
    */
-  def initialize(): this.type =
+  def initialize(async: Boolean): this.type =
     underlying match {
       case null ⇒
         val uid = ThreadLocalRandom.current.nextInt()
         swapCell(new UnstartedCell(system, this, props, supervisor, uid))
-        supervisor.sendSystemMessage(Supervise(this, uid))
+        supervisor.sendSystemMessage(Supervise(this, async, uid))
+        if (!async) point()
         this
-      case other ⇒ this
+      case other ⇒ throw new IllegalStateException("initialize called more than once!")
     }
 
   /**
@@ -69,7 +70,7 @@ private[akka] class RepointableActorRef(
    * modification of the `underlying` field, though it is safe to send messages
    * at any time.
    */
-  def activate(): this.type =
+  def point(): this.type =
     underlying match {
       case u: UnstartedCell ⇒ u.replaceWith(newCell(u)); this
       case null             ⇒ throw new IllegalStateException("underlying cell is null")
@@ -80,9 +81,8 @@ private[akka] class RepointableActorRef(
    * This is called by activate() to obtain the cell which is to replace the
    * unstarted cell. The cell must be fully functional.
    */
-  def newCell(old: Cell): Cell =
-    new ActorCell(system, this, props, supervisor).
-      init(old.asInstanceOf[UnstartedCell].uid, sendSupervise = false).start()
+  def newCell(old: UnstartedCell): Cell =
+    new ActorCell(system, this, props, supervisor).init(old.uid, sendSupervise = false).start()
 
   def start(): Unit = ()
 

akka-actor/src/main/scala/akka/actor/dungeon/Dispatch.scala

@@ -55,7 +55,7 @@ private[akka] trait Dispatch { this: ActorCell ⇒
 
     if (sendSupervise) {
       // ➡➡➡ NEVER SEND THE SAME SYSTEM MESSAGE OBJECT TO TWO ACTORS ⬅⬅⬅
-      parent.sendSystemMessage(akka.dispatch.Supervise(self, uid))
+      parent.sendSystemMessage(akka.dispatch.Supervise(self, async = false, uid))
       parent ! NullMessage // read ScalaDoc of NullMessage to see why
     }
     this

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

@@ -108,7 +108,7 @@ private[akka] case class Terminate() extends SystemMessage // sent to self from
 /**
  * INTERNAL API
  */
-private[akka] case class Supervise(child: ActorRef, uid: Int) extends SystemMessage // sent to supervisor ActorRef from ActorCell.start
+private[akka] case class Supervise(child: ActorRef, async: Boolean, uid: Int) extends SystemMessage // sent to supervisor ActorRef from ActorCell.start
 /**
  * INTERNAL API
  */

akka-actor/src/main/scala/akka/routing/Routing.scala

@@ -37,7 +37,7 @@ private[akka] class RoutedActorRef(_system: ActorSystemImpl, _props: Props, _sup
 
   _props.routerConfig.verifyConfig()
 
-  override def newCell(old: Cell): Cell = new RoutedActorCell(system, this, props, supervisor, old.asInstanceOf[UnstartedCell].uid)
+  override def newCell(old: UnstartedCell): Cell = new RoutedActorCell(system, this, props, supervisor, old.uid)
 
 }