Use ConcurrentQueue due a race condition. (#311)

src/ObjectTranslator.cs

@@ -2,6 +2,7 @@
 using System.IO;
 using System.Reflection;
 using System.Collections.Generic;
+using System.Collections.Concurrent;
 using System.Runtime.InteropServices;
 using KeraLua;
 
@@ -50,7 +51,7 @@ public int GetHashCode(object obj)
         // object # to object (FIXME - it should be possible to get object address as an object #)
         readonly Dictionary<int, object> _objects = new Dictionary<int, object>();
 
-        readonly Queue<int> finalizedReferences = new Queue<int>();
+        readonly ConcurrentQueue<int> finalizedReferences = new ConcurrentQueue<int>();
 
         internal EventHandlerContainer PendingEvents = new EventHandlerContainer();
         MetaFunctions metaFunctions;
@@ -1136,11 +1137,10 @@ void CleanFinalizedReferences(LuaState state)
             if (finalizedReferences.Count == 0)
                 return;
 
-            while (finalizedReferences.Count != 0)
-            {
-                int reference = finalizedReferences.Dequeue();
+            int reference;
+
+            while (finalizedReferences.TryDequeue(out reference))
                 state.Unref(LuaRegistry.Index, reference);
-            }
         }
     }
 }

tests/src/LuaTests.cs

@@ -2384,7 +2384,7 @@ void ImplicitlyCreateATable(Lua lua)
 
         void PleaseRunFinalizers()
         {
-            for (int i = 0; i < 20; i++)
+            for (int i = 0; i < 40; i++)
             {
                 GC.Collect();
                 GC.WaitForPendingFinalizers();
@@ -2412,6 +2412,7 @@ public void TestTableFinalizerDispose()
 
                 ImplicitlyCreateATable(lua);
 
+                lua.State.GarbageCollector(LuaGC.Collect, 0);
                 lua.State.GarbageCollector(LuaGC.Collect, 0);
 
                 int after2 = lua.State.GarbageCollector(LuaGC.Count, 0);