Experimental test to rate limit the incoming packet handler and try to always leave a worker thread available for other tasks

OpenSim/Framework/Util.cs

@@ -1330,6 +1330,27 @@ namespace OpenSim.Framework
             m_ThreadPool = new SmartThreadPool(2000, maxThreads, 2);
         }
 
+        public static int FireAndForgetCount()
+        {
+            const int MAX_SYSTEM_THREADS = 200;
+
+            switch (FireAndForgetMethod)
+            {
+                case FireAndForgetMethod.UnsafeQueueUserWorkItem:
+                case FireAndForgetMethod.QueueUserWorkItem:
+                case FireAndForgetMethod.BeginInvoke:
+                    int workerThreads, iocpThreads;
+                    ThreadPool.GetAvailableThreads(out workerThreads, out iocpThreads);
+                    return workerThreads;
+                case FireAndForgetMethod.SmartThreadPool:
+                    return m_ThreadPool.MaxThreads - m_ThreadPool.InUseThreads;
+                case FireAndForgetMethod.Thread:
+                    return MAX_SYSTEM_THREADS - System.Diagnostics.Process.GetCurrentProcess().Threads.Count;
+                default:
+                    throw new NotImplementedException();
+            }
+        }
+
         public static void FireAndForget(System.Threading.WaitCallback callback, object obj)
         {
             switch (FireAndForgetMethod)

OpenSim/Region/ClientStack/LindenUDP/LLUDPServer.cs

@@ -801,6 +801,14 @@ namespace OpenSim.Region.ClientStack.LindenUDP
                 {
                     IncomingPacket incomingPacket = null;
 
+                    // HACK: This is a test to try and rate limit packet handling on Mono.
+                    // If it works, a more elegant solution can be devised
+                    if (Util.FireAndForgetCount() < 2)
+                    {
+                        //m_log.Debug("[LLUDPSERVER]: Incoming packet handler is sleeping");
+                        Thread.Sleep(30);
+                    }
+
                     if (packetInbox.Dequeue(100, ref incomingPacket))
                         Util.FireAndForget(ProcessInPacket, incomingPacket);
                 }