Added lock around World.Update to prevent multiple updates occuring simultaneously (it happened!)

OpenSim.RegionServer/world/World.cs

@@ -41,6 +41,7 @@ namespace OpenSim.world
         private string m_regionName;
         private InventoryCache _inventoryCache;
         private AssetCache _assetCache;
+        private int updateLock;
 
         /// <summary>
         /// Creates a new World class, and a region to go with it.
@@ -52,6 +53,7 @@ namespace OpenSim.world
         {
             try
             {
+                updateLock = 0;
                 m_clientThreads = clientThreads;
                 m_regionHandle = regionHandle;
                 m_regionName = regionName;
@@ -182,6 +184,8 @@ namespace OpenSim.world
         /// Performs per-frame updates on the world, this should be the central world loop
         /// </summary>
         public void Update()
+        {
+            lock (updateLock)
             {
                 try
                 {
@@ -227,6 +231,7 @@ namespace OpenSim.world
                     OpenSim.Framework.Console.MainConsole.Instance.WriteLine("World.cs: Update() - Failed with exception " + e.ToString());
                 }
             }
+        }
 
         /// <summary>
         /// Loads a new storage subsystem from a named library