* Reduce the annoyingness of clients that continually request unfound textures (probably for some good reason) by dropping all subsequent requests after the first reply.

* Print out a console message every 20 tries rather than every single one.
* This weakens the problem but does not eliminate it

OpenSim/Region/Environment/Modules/UserTextureDownloadService.cs

@@ -60,6 +60,13 @@ namespace OpenSim.Region.Environment.Modules
         /// </summary>
         private readonly BlockingQueue<ITextureSender> m_sharedSendersQueue;
         
+        /// <summary>
+        /// We're going to record when we get a request for a particular missing texture for each client
+        /// XXX This is really a temporary solution to deal with the situation where a client continually requests
+        /// the same missing textures
+        /// </summary>
+        private readonly Dictionary<LLUUID, int> missingTextureRequests = new Dictionary<LLUUID, int>();
+        
         private readonly Scene m_scene;
         
         private readonly IClientAPI m_client;
@@ -137,6 +144,12 @@ namespace OpenSim.Region.Environment.Modules
                     // this on to the TextureSender it will blow up, so just discard for now.
                     // Needs investigation.
                     if (texture == null || texture.Data == null)
+                    {
+                        // We're only going to tell the client once about a missing texture, even if it keeps asking
+                        // XXX This is to reduce (but not resolve) a current problem where some clients keep requesting the same textures
+                        // - one might want to do this for all asset requests (or allow a number of retries) in the 
+                        // longer term.
+                        if (!missingTextureRequests.ContainsKey(textureID))
                         {
                             m_log.DebugFormat(
                                 "[USER TEXTURE DOWNLOAD SERVICE]: Queueing TextureNotFoundSender for {0}, client {1}", 
@@ -144,6 +157,21 @@ namespace OpenSim.Region.Environment.Modules
                            
                             ITextureSender textureNotFoundSender = new TextureNotFoundSender(m_client, textureID);
                             EnqueueTextureSender(textureNotFoundSender);
+                            missingTextureRequests.Add(textureID, 1);
+                        }
+                        else
+                        {
+                            int requests = missingTextureRequests[textureID] + 1;
+                            
+                            if (requests % 20 == 0)
+                            {
+                                m_log.WarnFormat(
+                                    "[USER TEXTURE DOWNLOAD SERVICE]: Received {0} requests for the missing texture {1} from client {2}", 
+                                    requests, textureID, m_client.AgentId);
+                            }
+                                                        
+                            missingTextureRequests[textureID] = requests;                            
+                        }
                     }
                     else
                     {