* All CheckRegion within an instance would use the same, global, bool for 'Available', which would lead to intermittent failures on parallell teleport requests.

* Solidified CheckRegion somewhat, adding a second try if the first failed.

OpenSim/Framework/Communications/IInterRegionCommunications.cs

@@ -32,8 +32,8 @@ namespace OpenSim.Framework.Communications
     public interface IInterRegionCommunications
     {
         string rdebugRegionName { get; set; }
-        bool Available { get; }
+
-        void CheckRegion(string address, uint port);
+        bool CheckRegion(string address, uint port);
         bool InformRegionOfChildAgent(ulong regionHandle, AgentCircuitData agentData);
         bool InformRegionOfPrimCrossing(ulong regionHandle, LLUUID primID, string objData, int XMLMethod);
         bool RegionUp(SerializableRegionInfo region, ulong regionhandle);

OpenSim/Region/Communications/Local/LocalBackEndServices.cs

@@ -51,16 +51,9 @@ namespace OpenSim.Region.Communications.Local
 
         public string _gdebugRegionName = String.Empty;
 
-        bool m_bAvailable=true;
+        public bool CheckRegion(string address, uint port)
-
-        public void CheckRegion(string address, uint port)
         {
-            m_bAvailable = true;
+            return true;
-        }
-
-        public bool Available
-        {
-            get { return m_bAvailable; }
         }
 
         public string gdebugRegionName

OpenSim/Region/Communications/OGS1/OGS1GridServices.cs

@@ -1558,36 +1558,60 @@ namespace OpenSim.Region.Communications.OGS1
         bool m_bAvailable = false;
         int timeOut = 10; //10 seconds
 
-        public void CheckRegion(string address, uint port)
+        public bool CheckRegion(string address, uint port, bool retry)
         {
-            m_bAvailable = false;
+            bool available = false;
-            IPAddress ia = null;
+            bool timed_out = true;
+
+            IPAddress ia;
             IPAddress.TryParse(address, out ia);
             IPEndPoint m_EndPoint = new IPEndPoint(ia, (int)port);
-            AsyncCallback ConnectedMethodCallback = new AsyncCallback(ConnectedMethod);
-            Socket socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
-            IAsyncResult ar = socket.BeginConnect(m_EndPoint, ConnectedMethodCallback, socket);
-            ar.AsyncWaitHandle.WaitOne(timeOut*1000, false);
-            Thread.Sleep(500);
-        }
 
-        public bool Available
+            AsyncCallback callback = delegate(IAsyncResult iar)
             {
-            get { return m_bAvailable; }
+                Socket s = (Socket)iar.AsyncState;
-        }
-
-        void ConnectedMethod(IAsyncResult ar)
-        {
-            Socket socket = (Socket)ar.AsyncState;
                 try
                 {
-                socket.EndConnect(ar);
+                    s.EndConnect(iar);
-                m_bAvailable = true;
+                    available = true;
+                    timed_out = false;
                 }
-            catch (Exception)
+                catch (Exception e)
                 {
+                    m_log.DebugFormat("Callback EndConnect exception: {0}:{1}", e.Message, e.StackTrace);
                 }
-            socket.Close();
+
+                s.Close();
+            };
+
+            try
+            {
+                Socket socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
+                IAsyncResult ar = socket.BeginConnect(m_EndPoint, callback, socket);
+                ar.AsyncWaitHandle.WaitOne(timeOut * 1000, false);
+            }
+            catch (Exception e)
+            {
+                m_log.DebugFormat("CheckRegion Socket Setup exception: {0}:{1}", e.Message, e.StackTrace);
+                return false;
+            }
+
+            if (timed_out)
+            {
+                m_log.DebugFormat("socket [{0}] timed out ({1}) waiting to obtain a connection.", m_EndPoint, timeOut * 1000);
+
+                if (retry)
+                {
+                    return CheckRegion(address, port, false);
+                }
+            }
+
+            return available;
+        }
+
+        public bool CheckRegion(string address, uint port)
+        {
+            return CheckRegion(address, port, true);
         }
 
         public void NoteDeadRegion(ulong regionhandle)

OpenSim/Region/Environment/Scenes/SceneCommunicationService.cs

@@ -580,8 +580,7 @@ namespace OpenSim.Region.Environment.Scenes
                     if (reg.RemotingAddress != "" && reg.RemotingPort != 0)
                     {
                         // region is remote. see if it is up
-                        m_commsProvider.InterRegion.CheckRegion(reg.RemotingAddress, reg.RemotingPort);
+                        destRegionUp = m_commsProvider.InterRegion.CheckRegion(reg.RemotingAddress, reg.RemotingPort);
-                        destRegionUp = m_commsProvider.InterRegion.Available;
                     }
                     else
                     {