From 59a0cce0c00c3cde6c3bb6753c47a6ae9266891f Mon Sep 17 00:00:00 2001
From: Philipp Haller <hallerp@gmail.com>
Date: Tue, 27 Nov 2007 10:56:51 +0000
Subject: Fixed issue with task scheduler creating too ma...

Fixed issue with task scheduler creating too many threads. Improved
actor termination code. Added size query to MessageQueue.
---
 src/actors/scala/actors/FJTaskScheduler2.scala |  3 ++-
 src/actors/scala/actors/MessageQueue.scala     | 18 +++++++++++++++++-
 src/actors/scala/actors/Scheduler.scala        | 13 +++++++++----
 3 files changed, 28 insertions(+), 6 deletions(-)

diff --git a/src/actors/scala/actors/FJTaskScheduler2.scala b/src/actors/scala/actors/FJTaskScheduler2.scala
index 0600f4d7b2..8b99b83f7c 100644
--- a/src/actors/scala/actors/FJTaskScheduler2.scala
+++ b/src/actors/scala/actors/FJTaskScheduler2.scala
@@ -114,7 +114,8 @@ class FJTaskScheduler2 extends Thread with IScheduler {
             if (Platform.currentTime - lastActivity >= TICK_FREQ
                 && coreSize < maxSize
                 && executor.checkPoolSize()) {
-                  // do nothing
+                  coreSize += 1
+                  lastActivity = Platform.currentTime
                 }
             else {
               if (pendingReactions <= 0) {
diff --git a/src/actors/scala/actors/MessageQueue.scala b/src/actors/scala/actors/MessageQueue.scala
index 4beacfe70b..8f2f6c72cc 100644
--- a/src/actors/scala/actors/MessageQueue.scala
+++ b/src/actors/scala/actors/MessageQueue.scala
@@ -41,7 +41,16 @@ class MessageQueue {
 
   def isEmpty = null eq last
 
+  private var _size = 0
+  def size = _size
+
+  protected def changeSize(diff: Int) = {
+    _size += diff
+  }
+
   def append(msg: Any, session: OutputChannel[Any]) = {
+    changeSize(1) // size always increases by 1
+
     if (null eq last) { // list empty
       val el = new MessageQueueElement
       el.msg = msg
@@ -59,7 +68,9 @@ class MessageQueue {
   }
 
   def extractFirst(p: Any => Boolean): MessageQueueElement = {
-    if (null eq last) null
+    changeSize(-1) // assume size decreases by 1
+
+    val msg = if (null eq last) null
     else {
       // test first element
       if (p(first.msg)) {
@@ -95,5 +106,10 @@ class MessageQueue {
         null
       }
     }
+
+    if (null eq msg)
+      changeSize(1) // correct wrong assumption
+
+    msg
   }
 }
diff --git a/src/actors/scala/actors/Scheduler.scala b/src/actors/scala/actors/Scheduler.scala
index ddf6df164b..cb10795899 100644
--- a/src/actors/scala/actors/Scheduler.scala
+++ b/src/actors/scala/actors/Scheduler.scala
@@ -85,11 +85,15 @@ object Scheduler {
     termHandlers += (a -> (() => f))
   }
 
-  def unPendReaction(a: Actor) {
+  def unPendReaction(a: Actor) = synchronized {
     // execute registered termination handler (if any)
     termHandlers.get(a) match {
-      case Some(handler) => handler()
-      case None => // do nothing
+      case Some(handler) =>
+        handler()
+        // remove mapping
+        termHandlers -= a
+      case None =>
+        // do nothing
     }
 
     // notify scheduler
@@ -159,7 +163,8 @@ class SingleThreadedScheduler extends IScheduler {
   }
 
   def execute(task: Runnable) {
-    if (Actor.tl.get.isInstanceOf[ActorProxy]) {
+    val a = Actor.tl.get.asInstanceOf[Actor]
+    if ((null ne a) && a.isInstanceOf[ActorProxy]) {
       // execute task immediately on same thread
       task.run()
       while (taskQ.length > 0) {
-- 
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