diff --git a/Implab.Diagnostics.Interactive/InteractiveListener.cs b/Implab.Diagnostics.Interactive/InteractiveListener.cs
--- a/Implab.Diagnostics.Interactive/InteractiveListener.cs
+++ b/Implab.Diagnostics.Interactive/InteractiveListener.cs
@@ -17,7 +17,7 @@ namespace Implab.Diagnostics.Interactive
         readonly Promise<object> m_guiStarted = new Promise<object>();
         
         readonly IPromise m_guiFinished;
-        readonly IPromise m_workerFinished = new Promise<object>();
+        //        readonly IPromise m_workerFinished = new Promise<object>();
         
         readonly MTQueue<TraceViewItem> m_queue = new MTQueue<TraceViewItem>();
         readonly AutoResetEvent m_queueEvent = new AutoResetEvent(false);
@@ -31,7 +31,7 @@ namespace Implab.Diagnostics.Interactive
 
         public InteractiveListener(bool global) : base(global) {
             m_guiFinished = AsyncPool.InvokeNewThread(GuiThread);
-            m_workerFinished = AsyncPool.InvokeNewThread(QueueThread);
+            /*m_workerFinished = */AsyncPool.InvokeNewThread(QueueThread);
 
             m_guiStarted.Join();
         }
diff --git a/Implab/Implab.csproj b/Implab/Implab.csproj
--- a/Implab/Implab.csproj
+++ b/Implab/Implab.csproj
@@ -46,6 +46,25 @@
     <ConsolePause>false</ConsolePause>
     <DefineConstants>NET_4_5</DefineConstants>
   </PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'DebugMono|AnyCPU' ">
+    <DebugSymbols>true</DebugSymbols>
+    <DebugType>full</DebugType>
+    <Optimize>false</Optimize>
+    <OutputPath>bin\Debug</OutputPath>
+    <DefineConstants>TRACE;DEBUG;NET_4_5;MONO</DefineConstants>
+    <ErrorReport>prompt</ErrorReport>
+    <WarningLevel>4</WarningLevel>
+    <RunCodeAnalysis>true</RunCodeAnalysis>
+    <ConsolePause>false</ConsolePause>
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'ReleaseMono|AnyCPU' ">
+    <Optimize>true</Optimize>
+    <OutputPath>bin\Release</OutputPath>
+    <DefineConstants>NET_4_5;MONO;</DefineConstants>
+    <ErrorReport>prompt</ErrorReport>
+    <WarningLevel>4</WarningLevel>
+    <ConsolePause>false</ConsolePause>
+  </PropertyGroup>
   <ItemGroup>
     <Reference Include="System" />
     <Reference Include="System.Xml" />
diff --git a/Implab/JSON/JSONXmlReader.cs b/Implab/JSON/JSONXmlReader.cs
--- a/Implab/JSON/JSONXmlReader.cs
+++ b/Implab/JSON/JSONXmlReader.cs
@@ -301,6 +301,9 @@ namespace Implab.JSON {
         }
 
         protected override void Dispose(bool disposing) {
+            #if MONO
+            disposing = true;
+            #endif
             if (disposing) {
                 m_parser.Dispose();
             }
diff --git a/Implab/ObjectPool.cs b/Implab/ObjectPool.cs
--- a/Implab/ObjectPool.cs
+++ b/Implab/ObjectPool.cs
@@ -1,31 +1,26 @@
 using System;
 using Implab.Parallels;
 using System.Threading;
+using System.Diagnostics;
+using System.Diagnostics.CodeAnalysis;
 
 namespace Implab {
-    public class ObjectPool<T> : IDisposable {
-        readonly Func<T> m_factory;
-        readonly Action<T> m_cleanup;
+    public abstract class ObjectPool<T> : IDisposable {
         readonly int m_size;
         readonly MTQueue<T> m_queue = new MTQueue<T>();
 
+        [SuppressMessage("Microsoft.Design", "CA1000:DoNotDeclareStaticMembersOnGenericTypes")]
+        static readonly bool _isValueType = typeof(T).IsValueType;
+
         bool m_disposed;
 
         int m_count;
 
-        public ObjectPool(Func<T> factory, Action<T> cleanup, int size) {
-            Safe.ArgumentNotNull(factory, "factory");
-            Safe.ArgumentInRange(size, 1, size, "size");
-
-            m_factory = factory;
-            m_cleanup = cleanup;
+        protected ObjectPool(int size) {
             m_size = size;
         }
 
-        public ObjectPool(Func<T> factory, Action<T> cleanup) : this(factory,cleanup,Environment.ProcessorCount+1) {
-        }
-
-        public ObjectPool(Func<T> factory) : this(factory,null,Environment.ProcessorCount+1) {
+        protected ObjectPool() : this(Environment.ProcessorCount+1) {
         }
 
         public ObjectPoolWrapper<T> AllocateAuto() {
@@ -35,24 +30,32 @@ namespace Implab {
 
         public T Allocate() {
             if (m_disposed)
-                throw new ObjectDisposedException(this.ToString());
+                throw new ObjectDisposedException(ToString());
 
             T instance;
             if (m_queue.TryDequeue(out instance)) {
                 Interlocked.Decrement(ref m_count);
             } else {
-                instance = m_factory();
+                instance = CreateInstance();
+                Debug.Assert(!Object.Equals(instance, default(T)) || _isValueType);
             }
             return instance;
         }
 
+        protected abstract T CreateInstance();
+
+        protected virtual void CleanupInstance(T instance) {
+        }
+
         public void Release(T instance) {
+            if ( Object.Equals(instance,default(T)) && !_isValueType)
+                return;
+
             Thread.MemoryBarrier();
             if (m_count < m_size && !m_disposed) {
                 Interlocked.Increment(ref m_count);
 
-                if (m_cleanup != null)
-                    m_cleanup(instance);
+                CleanupInstance(instance);
 
                 m_queue.Enqueue(instance);