17 files changed, 211 insertions, 131 deletions
diff --git a/src/csharp/Grpc.Core/Calls.cs b/src/csharp/Grpc.Core/Calls.cs
index 9f8baac684..750282258f 100644
--- a/src/csharp/Grpc.Core/Calls.cs
+++ b/src/csharp/Grpc.Core/Calls.cs
@@ -58,7 +58,7 @@ namespace Grpc.Core
             where TResponse : class
         {
             var asyncCall = new AsyncCall<TRequest, TResponse>(call.RequestMarshaller.Serializer, call.ResponseMarshaller.Deserializer);
-            asyncCall.Initialize(call.Channel, GetCompletionQueue(), call.Name);
+            asyncCall.Initialize(call.Channel, call.Channel.CompletionQueue, call.Name);
             var asyncResult = asyncCall.UnaryCallAsync(req, call.Headers);
             RegisterCancellationCallback(asyncCall, token);
             return await asyncResult;
@@ -69,7 +69,7 @@ namespace Grpc.Core
             where TResponse : class
         {
             var asyncCall = new AsyncCall<TRequest, TResponse>(call.RequestMarshaller.Serializer, call.ResponseMarshaller.Deserializer);
-            asyncCall.Initialize(call.Channel, GetCompletionQueue(), call.Name);
+            asyncCall.Initialize(call.Channel, call.Channel.CompletionQueue, call.Name);
             asyncCall.StartServerStreamingCall(req, call.Headers);
             RegisterCancellationCallback(asyncCall, token);
             var responseStream = new ClientResponseStream<TRequest, TResponse>(asyncCall);
@@ -81,7 +81,7 @@ namespace Grpc.Core
             where TResponse : class
         {
             var asyncCall = new AsyncCall<TRequest, TResponse>(call.RequestMarshaller.Serializer, call.ResponseMarshaller.Deserializer);
-            asyncCall.Initialize(call.Channel, GetCompletionQueue(), call.Name);
+            asyncCall.Initialize(call.Channel, call.Channel.CompletionQueue, call.Name);
             var resultTask = asyncCall.ClientStreamingCallAsync(call.Headers);
             RegisterCancellationCallback(asyncCall, token);
             var requestStream = new ClientRequestStream<TRequest, TResponse>(asyncCall);
@@ -93,7 +93,7 @@ namespace Grpc.Core
             where TResponse : class
         {
             var asyncCall = new AsyncCall<TRequest, TResponse>(call.RequestMarshaller.Serializer, call.ResponseMarshaller.Deserializer);
-            asyncCall.Initialize(call.Channel, GetCompletionQueue(), call.Name);
+            asyncCall.Initialize(call.Channel, call.Channel.CompletionQueue, call.Name);
             asyncCall.StartDuplexStreamingCall(call.Headers);
             RegisterCancellationCallback(asyncCall, token);
             var requestStream = new ClientRequestStream<TRequest, TResponse>(asyncCall);
@@ -108,13 +108,5 @@ namespace Grpc.Core
                 token.Register(() => asyncCall.Cancel());
             }
         }
-
-        /// <summary>
-        /// Gets shared completion queue used for async calls.
-        /// </summary>
-        private static CompletionQueueSafeHandle GetCompletionQueue()
-        {
-            return GrpcEnvironment.ThreadPool.CompletionQueue;
-        }
     }
 }
diff --git a/src/csharp/Grpc.Core/Channel.cs b/src/csharp/Grpc.Core/Channel.cs
index d6bfbb7bc4..5baf260003 100644
--- a/src/csharp/Grpc.Core/Channel.cs
+++ b/src/csharp/Grpc.Core/Channel.cs
@@ -42,8 +42,10 @@ namespace Grpc.Core
     /// </summary>
     public class Channel : IDisposable
     {
+        readonly GrpcEnvironment environment;
         readonly ChannelSafeHandle handle;
         readonly string target;
+        bool disposed;
 
         /// <summary>
         /// Creates a channel that connects to a specific host.
@@ -54,6 +56,7 @@ namespace Grpc.Core
         /// <param name="options">Channel options.</param>
         public Channel(string host, Credentials credentials = null, IEnumerable<ChannelOption> options = null)
         {
+            this.environment = GrpcEnvironment.GetInstance();
             using (ChannelArgsSafeHandle nativeChannelArgs = ChannelOptions.CreateChannelArgs(options))
             {
                 if (credentials != null)
@@ -105,10 +108,35 @@ namespace Grpc.Core
             }
         }
 
+        internal CompletionQueueSafeHandle CompletionQueue
+        {
+            get
+            {
+                return this.environment.CompletionQueue;
+            }
+        }
+
+        internal CompletionRegistry CompletionRegistry
+        {
+            get
+            {
+                return this.environment.CompletionRegistry;
+            }
+        }
+
+        internal GrpcEnvironment Environment
+        {
+            get
+            {
+                return this.environment;
+            }
+        }
+
         protected virtual void Dispose(bool disposing)
         {
-            if (handle != null && !handle.IsInvalid)
+            if (disposing && handle != null && !disposed)
             {
+                disposed = true;
                 handle.Dispose();
             }
         }
diff --git a/src/csharp/Grpc.Core/Grpc.Core.csproj b/src/csharp/Grpc.Core/Grpc.Core.csproj
index a36a6a5acc..cde42c3b7e 100644
--- a/src/csharp/Grpc.Core/Grpc.Core.csproj
+++ b/src/csharp/Grpc.Core/Grpc.Core.csproj
@@ -33,8 +33,9 @@
   </PropertyGroup>
   <ItemGroup>
     <Reference Include="System" />
-    <Reference Include="System.Collections.Immutable">
-      <HintPath>..\packages\Microsoft.Bcl.Immutable.1.0.34\lib\portable-net45+win8+wp8+wpa81\System.Collections.Immutable.dll</HintPath>
+    <Reference Include="System.Collections.Immutable, Version=1.1.36.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL">
+      <SpecificVersion>False</SpecificVersion>
+      <HintPath>..\packages\System.Collections.Immutable.1.1.36\lib\portable-net45+win8+wp8+wpa81\System.Collections.Immutable.dll</HintPath>
     </Reference>
     <Reference Include="System.Interactive.Async">
       <HintPath>..\packages\Ix-Async.1.2.3\lib\net45\System.Interactive.Async.dll</HintPath>
@@ -48,6 +49,7 @@
     <Compile Include="IAsyncStreamWriter.cs" />
     <Compile Include="IAsyncStreamReader.cs" />
     <Compile Include="Internal\GrpcLog.cs" />
+    <Compile Include="Version.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
     <Compile Include="RpcException.cs" />
     <Compile Include="Calls.cs" />
@@ -103,6 +105,7 @@
     <Compile Include="ChannelOptions.cs" />
   </ItemGroup>
   <ItemGroup>
+    <None Include="Grpc.Core.nuspec" />
     <None Include="packages.config" />
   </ItemGroup>
   <Choose>
@@ -130,4 +133,4 @@
   </Target>
   <Import Project="..\packages\grpc.dependencies.openssl.redist.1.0.2.2\build\portable-net45\grpc.dependencies.openssl.redist.targets" Condition="Exists('..\packages\grpc.dependencies.openssl.redist.1.0.2.2\build\portable-net45\grpc.dependencies.openssl.redist.targets')" />
   <Import Project="..\packages\grpc.dependencies.zlib.redist.1.2.8.9\build\portable-net45\grpc.dependencies.zlib.redist.targets" Condition="Exists('..\packages\grpc.dependencies.zlib.redist.1.2.8.9\build\portable-net45\grpc.dependencies.zlib.redist.targets')" />
-</Project>
+</Project>
+\ No newline at end of file
diff --git a/src/csharp/Grpc.Core/Grpc.Core.nuspec b/src/csharp/Grpc.Core/Grpc.Core.nuspec
index 629b978fdf..5ace6dcf89 100644
--- a/src/csharp/Grpc.Core/Grpc.Core.nuspec
+++ b/src/csharp/Grpc.Core/Grpc.Core.nuspec
@@ -5,19 +5,19 @@
     <title>gRPC C# Core</title>
     <summary>Core C# implementation of gRPC - an RPC library and framework</summary>
     <description>Core C# implementation of gRPC - an RPC library and framework. See project site for more info.</description>
-    <version>0.5.1</version>
+    <version>$version$</version>
     <authors>Google Inc.</authors>
     <owners>grpc-packages</owners>
     <licenseUrl>https://github.com/grpc/grpc/blob/master/LICENSE</licenseUrl>
     <projectUrl>https://github.com/grpc/grpc</projectUrl>
     <requireLicenseAcceptance>false</requireLicenseAcceptance>
-    <releaseNotes>Release 0.5.1 of gRPC C#</releaseNotes>
+    <releaseNotes>Release $version$ of gRPC C#</releaseNotes>
     <copyright>Copyright 2015, Google Inc.</copyright>
     <tags>gRPC RPC Protocol HTTP/2</tags>
 	<dependencies>
-	  <dependency id="Microsoft.Bcl.Immutable" version="1.0.34" />
+	  <dependency id="System.Collections.Immutable" version="1.1.36" />
 	  <dependency id="Ix-Async" version="1.2.3" />
-	  <dependency id="grpc.native.csharp_ext" version="0.9.1" />
+	  <dependency id="grpc.native.csharp_ext" version="$GrpcNativeCsharpExtVersion$" />
     </dependencies>
   </metadata>
   <files>
diff --git a/src/csharp/Grpc.Core/GrpcEnvironment.cs b/src/csharp/Grpc.Core/GrpcEnvironment.cs
index 30ff289714..47d1651aab 100644
--- a/src/csharp/Grpc.Core/GrpcEnvironment.cs
+++ b/src/csharp/Grpc.Core/GrpcEnvironment.cs
@@ -33,7 +33,9 @@
 
 using System;
 using System.Runtime.InteropServices;
+using System.Threading.Tasks;
 using Grpc.Core.Internal;
+using Grpc.Core.Utils;
 
 namespace Grpc.Core
 {
@@ -51,20 +53,18 @@ namespace Grpc.Core
         static extern void grpcsharp_shutdown();
 
         static object staticLock = new object();
-        static volatile GrpcEnvironment instance;
+        static GrpcEnvironment instance;
 
         readonly GrpcThreadPool threadPool;
         readonly CompletionRegistry completionRegistry;
+        readonly DebugStats debugStats = new DebugStats();
         bool isClosed;
 
         /// <summary>
-        /// Makes sure GRPC environment is initialized. Subsequent invocations don't have any
-        /// effect unless you call Shutdown first.
-        /// Although normal use cases assume you will call this just once in your application's
-        /// lifetime (and call Shutdown once you're done), for the sake of easier testing it's
-        /// allowed to initialize the environment again after it has been successfully shutdown.
+        /// Returns an instance of initialized gRPC environment.
+        /// Subsequent invocations return the same instance unless Shutdown has been called first.
         /// </summary>
-        public static void Initialize()
+        internal static GrpcEnvironment GetInstance()
         {
             lock (staticLock)
             {
@@ -72,12 +72,13 @@ namespace Grpc.Core
                 {
                     instance = new GrpcEnvironment();
                 }
+                return instance;
             }
         }
 
         /// <summary>
-        /// Shuts down the GRPC environment if it was initialized before.
-        /// Repeated invocations have no effect.
+        /// Shuts down the gRPC environment if it was initialized before.
+        /// Blocks until the environment has been fully shutdown.
         /// </summary>
         public static void Shutdown()
         {
@@ -87,50 +88,55 @@ namespace Grpc.Core
                 {
                     instance.Close();
                     instance = null;
-
-                    CheckDebugStats();
                 }
             }
         }
 
-        internal static GrpcThreadPool ThreadPool
+        /// <summary>
+        /// Creates gRPC environment.
+        /// </summary>
+        private GrpcEnvironment()
+        {
+            GrpcLog.RedirectNativeLogs(Console.Error);
+            grpcsharp_init();
+            completionRegistry = new CompletionRegistry(this);
+            threadPool = new GrpcThreadPool(this, THREAD_POOL_SIZE);
+            threadPool.Start();
+            // TODO: use proper logging here
+            Console.WriteLine("GRPC initialized.");
+        }
+
+        /// <summary>
+        /// Gets the completion registry used by this gRPC environment.
+        /// </summary>
+        internal CompletionRegistry CompletionRegistry
         {
             get
             {
-                var inst = instance;
-                if (inst == null)
-                {
-                    throw new InvalidOperationException("GRPC environment not initialized");
-                }
-                return inst.threadPool;
+                return this.completionRegistry;
             }
         }
 
-        internal static CompletionRegistry CompletionRegistry
+        /// <summary>
+        /// Gets the completion queue used by this gRPC environment.
+        /// </summary>
+        internal CompletionQueueSafeHandle CompletionQueue
         {
             get
             {
-                var inst = instance;
-                if (inst == null)
-                {
-                    throw new InvalidOperationException("GRPC environment not initialized");
-                }
-                return inst.completionRegistry;
+                return this.threadPool.CompletionQueue;
             }
         }
 
         /// <summary>
-        /// Creates gRPC environment.
+        /// Gets the completion queue used by this gRPC environment.
         /// </summary>
-        private GrpcEnvironment()
+        internal DebugStats DebugStats
         {
-            GrpcLog.RedirectNativeLogs(Console.Error);
-            grpcsharp_init();
-            completionRegistry = new CompletionRegistry();
-            threadPool = new GrpcThreadPool(THREAD_POOL_SIZE);
-            threadPool.Start();
-            // TODO: use proper logging here
-            Console.WriteLine("GRPC initialized.");
+            get
+            {
+                return this.debugStats;
+            }
         }
 
         /// <summary>
@@ -146,32 +152,28 @@ namespace Grpc.Core
             grpcsharp_shutdown();
             isClosed = true;
 
+            debugStats.CheckOK();
+
             // TODO: use proper logging here
             Console.WriteLine("GRPC shutdown.");
         }
 
-        private static void CheckDebugStats()
+        /// <summary>
+        /// Shuts down this environment asynchronously.
+        /// </summary>
+        private Task CloseAsync()
         {
-            var remainingClientCalls = DebugStats.ActiveClientCalls.Count;
-            if (remainingClientCalls != 0)
-            {                
-                DebugWarning(string.Format("Detected {0} client calls that weren't disposed properly.", remainingClientCalls));
-            }
-            var remainingServerCalls = DebugStats.ActiveServerCalls.Count;
-            if (remainingServerCalls != 0)
-            {
-                DebugWarning(string.Format("Detected {0} server calls that weren't disposed properly.", remainingServerCalls));
-            }
-            var pendingBatchCompletions = DebugStats.PendingBatchCompletions.Count;
-            if (pendingBatchCompletions != 0)
+            return Task.Run(() =>
             {
-                DebugWarning(string.Format("Detected {0} pending batch completions.", pendingBatchCompletions));
-            }
-        }
-
-        private static void DebugWarning(string message)
-        {
-            throw new Exception("Shutdown check: " + message);
+                try
+                {
+                    Close();
+                }
+                catch (Exception e)
+                {
+                    Console.WriteLine("Error occured while shutting down GrpcEnvironment: " + e);
+                }
+            });
         }
     }
 }
diff --git a/src/csharp/Grpc.Core/Internal/AsyncCall.cs b/src/csharp/Grpc.Core/Internal/AsyncCall.cs
index d350f45da6..24b75d1668 100644
--- a/src/csharp/Grpc.Core/Internal/AsyncCall.cs
+++ b/src/csharp/Grpc.Core/Internal/AsyncCall.cs
@@ -47,6 +47,8 @@ namespace Grpc.Core.Internal
     /// </summary>
     internal class AsyncCall<TRequest, TResponse> : AsyncCallBase<TRequest, TResponse>
     {
+        Channel channel;
+
         // Completion of a pending unary response if not null.
         TaskCompletionSource<TResponse> unaryResponseTcs;
 
@@ -61,8 +63,9 @@ namespace Grpc.Core.Internal
 
         public void Initialize(Channel channel, CompletionQueueSafeHandle cq, string methodName)
         {
-            var call = CallSafeHandle.Create(channel.Handle, cq, methodName, channel.Target, Timespec.InfFuture);
-            DebugStats.ActiveClientCalls.Increment();
+            this.channel = channel;
+            var call = CallSafeHandle.Create(channel.Handle, channel.CompletionRegistry, cq, methodName, channel.Target, Timespec.InfFuture);
+            channel.Environment.DebugStats.ActiveClientCalls.Increment();
             InitializeInternal(call);
         }
 
@@ -277,7 +280,7 @@ namespace Grpc.Core.Internal
 
         protected override void OnReleaseResources()
         {
-            DebugStats.ActiveClientCalls.Decrement();
+            channel.Environment.DebugStats.ActiveClientCalls.Decrement();
         }
 
         /// <summary>
diff --git a/src/csharp/Grpc.Core/Internal/AsyncCallServer.cs b/src/csharp/Grpc.Core/Internal/AsyncCallServer.cs
index 4f510ba40a..309067ea9d 100644
--- a/src/csharp/Grpc.Core/Internal/AsyncCallServer.cs
+++ b/src/csharp/Grpc.Core/Internal/AsyncCallServer.cs
@@ -48,14 +48,17 @@ namespace Grpc.Core.Internal
     internal class AsyncCallServer<TRequest, TResponse> : AsyncCallBase<TResponse, TRequest>
     {
         readonly TaskCompletionSource<object> finishedServersideTcs = new TaskCompletionSource<object>();
+        readonly GrpcEnvironment environment;
 
-        public AsyncCallServer(Func<TResponse, byte[]> serializer, Func<byte[], TRequest> deserializer) : base(serializer, deserializer)
+        public AsyncCallServer(Func<TResponse, byte[]> serializer, Func<byte[], TRequest> deserializer, GrpcEnvironment environment) : base(serializer, deserializer)
         {
+            this.environment = Preconditions.CheckNotNull(environment);
         }
 
         public void Initialize(CallSafeHandle call)
         {
-            DebugStats.ActiveServerCalls.Increment();
+            call.SetCompletionRegistry(environment.CompletionRegistry);
+            environment.DebugStats.ActiveServerCalls.Increment();
             InitializeInternal(call);
         }
 
@@ -114,7 +117,7 @@ namespace Grpc.Core.Internal
 
         protected override void OnReleaseResources()
         {
-            DebugStats.ActiveServerCalls.Decrement();
+            environment.DebugStats.ActiveServerCalls.Decrement();
         }
 
         /// <summary>
diff --git a/src/csharp/Grpc.Core/Internal/CallSafeHandle.cs b/src/csharp/Grpc.Core/Internal/CallSafeHandle.cs
index ef92b44402..3b246ac01b 100644
--- a/src/csharp/Grpc.Core/Internal/CallSafeHandle.cs
+++ b/src/csharp/Grpc.Core/Internal/CallSafeHandle.cs
@@ -43,6 +43,7 @@ namespace Grpc.Core.Internal
     internal class CallSafeHandle : SafeHandleZeroIsInvalid
     {
         const uint GRPC_WRITE_BUFFER_HINT = 1;
+        CompletionRegistry completionRegistry;
 
         [DllImport("grpc_csharp_ext.dll")]
         static extern CallSafeHandle grpcsharp_channel_create_call(ChannelSafeHandle channel, CompletionQueueSafeHandle cq, string method, string host, Timespec deadline);
@@ -97,15 +98,22 @@ namespace Grpc.Core.Internal
         {
         }
 
-        public static CallSafeHandle Create(ChannelSafeHandle channel, CompletionQueueSafeHandle cq, string method, string host, Timespec deadline)
+        public static CallSafeHandle Create(ChannelSafeHandle channel, CompletionRegistry registry, CompletionQueueSafeHandle cq, string method, string host, Timespec deadline)
         {
-            return grpcsharp_channel_create_call(channel, cq, method, host, deadline);
+            var result = grpcsharp_channel_create_call(channel, cq, method, host, deadline);
+            result.SetCompletionRegistry(registry);
+            return result;
+        }
+
+        public void SetCompletionRegistry(CompletionRegistry completionRegistry)
+        {
+            this.completionRegistry = completionRegistry;
         }
 
         public void StartUnary(byte[] payload, BatchCompletionDelegate callback, MetadataArraySafeHandle metadataArray)
         {
             var ctx = BatchContextSafeHandle.Create();
-            GrpcEnvironment.CompletionRegistry.RegisterBatchCompletion(ctx, callback);
+            completionRegistry.RegisterBatchCompletion(ctx, callback);
             grpcsharp_call_start_unary(this, ctx, payload, new UIntPtr((ulong)payload.Length), metadataArray)
                 .CheckOk();
         }
@@ -119,56 +127,56 @@ namespace Grpc.Core.Internal
         public void StartClientStreaming(BatchCompletionDelegate callback, MetadataArraySafeHandle metadataArray)
         {
             var ctx = BatchContextSafeHandle.Create();
-            GrpcEnvironment.CompletionRegistry.RegisterBatchCompletion(ctx, callback);
+            completionRegistry.RegisterBatchCompletion(ctx, callback);
             grpcsharp_call_start_client_streaming(this, ctx, metadataArray).CheckOk();
         }
 
         public void StartServerStreaming(byte[] payload, BatchCompletionDelegate callback, MetadataArraySafeHandle metadataArray)
         {
             var ctx = BatchContextSafeHandle.Create();
-            GrpcEnvironment.CompletionRegistry.RegisterBatchCompletion(ctx, callback);
+            completionRegistry.RegisterBatchCompletion(ctx, callback);
             grpcsharp_call_start_server_streaming(this, ctx, payload, new UIntPtr((ulong)payload.Length), metadataArray).CheckOk();
         }
 
         public void StartDuplexStreaming(BatchCompletionDelegate callback, MetadataArraySafeHandle metadataArray)
         {
             var ctx = BatchContextSafeHandle.Create();
-            GrpcEnvironment.CompletionRegistry.RegisterBatchCompletion(ctx, callback);
+            completionRegistry.RegisterBatchCompletion(ctx, callback);
             grpcsharp_call_start_duplex_streaming(this, ctx, metadataArray).CheckOk();
         }
 
         public void StartSendMessage(byte[] payload, BatchCompletionDelegate callback)
         {
             var ctx = BatchContextSafeHandle.Create();
-            GrpcEnvironment.CompletionRegistry.RegisterBatchCompletion(ctx, callback);
+            completionRegistry.RegisterBatchCompletion(ctx, callback);
             grpcsharp_call_send_message(this, ctx, payload, new UIntPtr((ulong)payload.Length)).CheckOk();
         }
 
         public void StartSendCloseFromClient(BatchCompletionDelegate callback)
         {
             var ctx = BatchContextSafeHandle.Create();
-            GrpcEnvironment.CompletionRegistry.RegisterBatchCompletion(ctx, callback);
+            completionRegistry.RegisterBatchCompletion(ctx, callback);
             grpcsharp_call_send_close_from_client(this, ctx).CheckOk();
         }
 
         public void StartSendStatusFromServer(Status status, BatchCompletionDelegate callback)
         {
             var ctx = BatchContextSafeHandle.Create();
-            GrpcEnvironment.CompletionRegistry.RegisterBatchCompletion(ctx, callback);
+            completionRegistry.RegisterBatchCompletion(ctx, callback);
             grpcsharp_call_send_status_from_server(this, ctx, status.StatusCode, status.Detail).CheckOk();
         }
 
         public void StartReceiveMessage(BatchCompletionDelegate callback)
         {
             var ctx = BatchContextSafeHandle.Create();
-            GrpcEnvironment.CompletionRegistry.RegisterBatchCompletion(ctx, callback);
+            completionRegistry.RegisterBatchCompletion(ctx, callback);
             grpcsharp_call_recv_message(this, ctx).CheckOk();
         }
 
         public void StartServerSide(BatchCompletionDelegate callback)
         {
             var ctx = BatchContextSafeHandle.Create();
-            GrpcEnvironment.CompletionRegistry.RegisterBatchCompletion(ctx, callback);
+            completionRegistry.RegisterBatchCompletion(ctx, callback);
             grpcsharp_call_start_serverside(this, ctx).CheckOk();
         }
 
diff --git a/src/csharp/Grpc.Core/Internal/CompletionRegistry.cs b/src/csharp/Grpc.Core/Internal/CompletionRegistry.cs
index 80f006ae50..f6d8aa0600 100644
--- a/src/csharp/Grpc.Core/Internal/CompletionRegistry.cs
+++ b/src/csharp/Grpc.Core/Internal/CompletionRegistry.cs
@@ -45,11 +45,17 @@ namespace Grpc.Core.Internal
 
     internal class CompletionRegistry
     {
-        readonly ConcurrentDictionary<IntPtr, OpCompletionDelegate> dict = new ConcurrentDictionary<IntPtr, OpCompletionDelegate>();  
+        readonly GrpcEnvironment environment;
+        readonly ConcurrentDictionary<IntPtr, OpCompletionDelegate> dict = new ConcurrentDictionary<IntPtr, OpCompletionDelegate>();
+
+        public CompletionRegistry(GrpcEnvironment environment)
+        {
+            this.environment = environment;
+        }
 
         public void Register(IntPtr key, OpCompletionDelegate callback)
         {
-            DebugStats.PendingBatchCompletions.Increment();
+            environment.DebugStats.PendingBatchCompletions.Increment();
             Preconditions.CheckState(dict.TryAdd(key, callback));
         }
 
@@ -63,7 +69,7 @@ namespace Grpc.Core.Internal
         {
             OpCompletionDelegate value;
             Preconditions.CheckState(dict.TryRemove(key, out value));
-            DebugStats.PendingBatchCompletions.Decrement();
+            environment.DebugStats.PendingBatchCompletions.Decrement();
             return value;
         }
 
diff --git a/src/csharp/Grpc.Core/Internal/DebugStats.cs b/src/csharp/Grpc.Core/Internal/DebugStats.cs
index ef9d9afe11..8793450ff3 100644
--- a/src/csharp/Grpc.Core/Internal/DebugStats.cs
+++ b/src/csharp/Grpc.Core/Internal/DebugStats.cs
@@ -36,12 +36,39 @@ using System.Threading;
 
 namespace Grpc.Core.Internal
 {
-    internal static class DebugStats
+    internal class DebugStats
     {
-        public static readonly AtomicCounter ActiveClientCalls = new AtomicCounter();
+        public readonly AtomicCounter ActiveClientCalls = new AtomicCounter();
 
-        public static readonly AtomicCounter ActiveServerCalls = new AtomicCounter();
+        public readonly AtomicCounter ActiveServerCalls = new AtomicCounter();
 
-        public static readonly AtomicCounter PendingBatchCompletions = new AtomicCounter();
+        public readonly AtomicCounter PendingBatchCompletions = new AtomicCounter();
+
+        /// <summary>
+        /// Checks the debug stats and take action for any inconsistency found.
+        /// </summary>
+        public void CheckOK()
+        {
+            var remainingClientCalls = ActiveClientCalls.Count;
+            if (remainingClientCalls != 0)
+            {                
+                DebugWarning(string.Format("Detected {0} client calls that weren't disposed properly.", remainingClientCalls));
+            }
+            var remainingServerCalls = ActiveServerCalls.Count;
+            if (remainingServerCalls != 0)
+            {
+                DebugWarning(string.Format("Detected {0} server calls that weren't disposed properly.", remainingServerCalls));
+            }
+            var pendingBatchCompletions = PendingBatchCompletions.Count;
+            if (pendingBatchCompletions != 0)
+            {
+                DebugWarning(string.Format("Detected {0} pending batch completions.", pendingBatchCompletions));
+            }
+        }
+
+        private void DebugWarning(string message)
+        {
+            throw new Exception("Shutdown check: " + message);
+        }
     }
 }
diff --git a/src/csharp/Grpc.Core/Internal/GrpcThreadPool.cs b/src/csharp/Grpc.Core/Internal/GrpcThreadPool.cs
index 89b44a4e2b..b77e893044 100644
--- a/src/csharp/Grpc.Core/Internal/GrpcThreadPool.cs
+++ b/src/csharp/Grpc.Core/Internal/GrpcThreadPool.cs
@@ -45,14 +45,16 @@ namespace Grpc.Core.Internal
     /// </summary>
     internal class GrpcThreadPool
     {
+        readonly GrpcEnvironment environment;
         readonly object myLock = new object();
         readonly List<Thread> threads = new List<Thread>();
         readonly int poolSize;
 
         CompletionQueueSafeHandle cq;
 
-        public GrpcThreadPool(int poolSize)
+        public GrpcThreadPool(GrpcEnvironment environment, int poolSize)
         {
+            this.environment = environment;
             this.poolSize = poolSize;
         }
 
@@ -80,7 +82,7 @@ namespace Grpc.Core.Internal
             {
                 cq.Shutdown();
 
-                Console.WriteLine("Waiting for GPRC threads to finish.");
+                Console.WriteLine("Waiting for GRPC threads to finish.");
                 foreach (var thread in threads)
                 {
                     thread.Join();
@@ -122,7 +124,7 @@ namespace Grpc.Core.Internal
                     IntPtr tag = ev.tag;
                     try
                     {
-                        var callback = GrpcEnvironment.CompletionRegistry.Extract(tag);
+                        var callback = environment.CompletionRegistry.Extract(tag);
                         callback(success);
                     }
                     catch (Exception e)
diff --git a/src/csharp/Grpc.Core/Internal/ServerCallHandler.cs b/src/csharp/Grpc.Core/Internal/ServerCallHandler.cs
index c0e5bae13f..594e46b159 100644
--- a/src/csharp/Grpc.Core/Internal/ServerCallHandler.cs
+++ b/src/csharp/Grpc.Core/Internal/ServerCallHandler.cs
@@ -42,7 +42,7 @@ namespace Grpc.Core.Internal
 {
     internal interface IServerCallHandler
     {
-        Task HandleCall(string methodName, CallSafeHandle call, CompletionQueueSafeHandle cq);
+        Task HandleCall(string methodName, CallSafeHandle call, GrpcEnvironment environment);
     }
 
     internal class UnaryServerCallHandler<TRequest, TResponse> : IServerCallHandler
@@ -58,11 +58,12 @@ namespace Grpc.Core.Internal
             this.handler = handler;
         }
 
-        public async Task HandleCall(string methodName, CallSafeHandle call, CompletionQueueSafeHandle cq)
+        public async Task HandleCall(string methodName, CallSafeHandle call, GrpcEnvironment environment)
         {
             var asyncCall = new AsyncCallServer<TRequest, TResponse>(
                 method.ResponseMarshaller.Serializer,
-                method.RequestMarshaller.Deserializer);
+                method.RequestMarshaller.Deserializer,
+                environment);
 
             asyncCall.Initialize(call);
             var finishedTask = asyncCall.ServerSideCallAsync();
@@ -110,11 +111,12 @@ namespace Grpc.Core.Internal
             this.handler = handler;
         }
 
-        public async Task HandleCall(string methodName, CallSafeHandle call, CompletionQueueSafeHandle cq)
+        public async Task HandleCall(string methodName, CallSafeHandle call, GrpcEnvironment environment)
         {
             var asyncCall = new AsyncCallServer<TRequest, TResponse>(
                 method.ResponseMarshaller.Serializer,
-                method.RequestMarshaller.Deserializer);
+                method.RequestMarshaller.Deserializer,
+                environment);
 
             asyncCall.Initialize(call);
             var finishedTask = asyncCall.ServerSideCallAsync();
@@ -163,11 +165,12 @@ namespace Grpc.Core.Internal
             this.handler = handler;
         }
 
-        public async Task HandleCall(string methodName, CallSafeHandle call, CompletionQueueSafeHandle cq)
+        public async Task HandleCall(string methodName, CallSafeHandle call, GrpcEnvironment environment)
         {
             var asyncCall = new AsyncCallServer<TRequest, TResponse>(
                 method.ResponseMarshaller.Serializer,
-                method.RequestMarshaller.Deserializer);
+                method.RequestMarshaller.Deserializer,
+                environment);
 
             asyncCall.Initialize(call);
             var finishedTask = asyncCall.ServerSideCallAsync();
@@ -219,11 +222,12 @@ namespace Grpc.Core.Internal
             this.handler = handler;
         }
 
-        public async Task HandleCall(string methodName, CallSafeHandle call, CompletionQueueSafeHandle cq)
+        public async Task HandleCall(string methodName, CallSafeHandle call, GrpcEnvironment environment)
         {
             var asyncCall = new AsyncCallServer<TRequest, TResponse>(
                 method.ResponseMarshaller.Serializer,
-                method.RequestMarshaller.Deserializer);
+                method.RequestMarshaller.Deserializer,
+                environment);
 
             asyncCall.Initialize(call);
             var finishedTask = asyncCall.ServerSideCallAsync();
@@ -255,11 +259,11 @@ namespace Grpc.Core.Internal
 
     internal class NoSuchMethodCallHandler : IServerCallHandler
     {
-        public async Task HandleCall(string methodName, CallSafeHandle call, CompletionQueueSafeHandle cq)
+        public async Task HandleCall(string methodName, CallSafeHandle call, GrpcEnvironment environment)
         {
             // We don't care about the payload type here.
             var asyncCall = new AsyncCallServer<byte[], byte[]>(
-                (payload) => payload, (payload) => payload);
+                (payload) => payload, (payload) => payload, environment);
             
             asyncCall.Initialize(call);
             var finishedTask = asyncCall.ServerSideCallAsync();
diff --git a/src/csharp/Grpc.Core/Internal/ServerSafeHandle.cs b/src/csharp/Grpc.Core/Internal/ServerSafeHandle.cs
index 83dbb910aa..9e1170e6dd 100644
--- a/src/csharp/Grpc.Core/Internal/ServerSafeHandle.cs
+++ b/src/csharp/Grpc.Core/Internal/ServerSafeHandle.cs
@@ -91,19 +91,19 @@ namespace Grpc.Core.Internal
         {
             grpcsharp_server_start(this);
         }
-            
-        public void ShutdownAndNotify(CompletionQueueSafeHandle cq, BatchCompletionDelegate callback)
+    
+        public void ShutdownAndNotify(BatchCompletionDelegate callback, GrpcEnvironment environment)
         {
             var ctx = BatchContextSafeHandle.Create();
-            GrpcEnvironment.CompletionRegistry.RegisterBatchCompletion(ctx, callback);
-            grpcsharp_server_shutdown_and_notify_callback(this, cq, ctx);
+            environment.CompletionRegistry.RegisterBatchCompletion(ctx, callback);
+            grpcsharp_server_shutdown_and_notify_callback(this, environment.CompletionQueue, ctx);
         }
 
-        public void RequestCall(CompletionQueueSafeHandle cq, BatchCompletionDelegate callback)
+        public void RequestCall(BatchCompletionDelegate callback, GrpcEnvironment environment)
         {
             var ctx = BatchContextSafeHandle.Create();
-            GrpcEnvironment.CompletionRegistry.RegisterBatchCompletion(ctx, callback);
-            grpcsharp_server_request_call(this, cq, ctx).CheckOk();
+            environment.CompletionRegistry.RegisterBatchCompletion(ctx, callback);
+            grpcsharp_server_request_call(this, environment.CompletionQueue, ctx).CheckOk();
         }
 
         protected override bool ReleaseHandle()
diff --git a/src/csharp/Grpc.Core/Properties/AssemblyInfo.cs b/src/csharp/Grpc.Core/Properties/AssemblyInfo.cs
index 03b682181a..2b3d7530f2 100644
--- a/src/csharp/Grpc.Core/Properties/AssemblyInfo.cs
+++ b/src/csharp/Grpc.Core/Properties/AssemblyInfo.cs
@@ -9,6 +9,5 @@ using System.Runtime.CompilerServices;
 [assembly: AssemblyCopyright("Google Inc.  All rights reserved.")]
 [assembly: AssemblyTrademark("")]
 [assembly: AssemblyCulture("")]
-[assembly: AssemblyVersion("0.5.*")]
 
 [assembly: InternalsVisibleTo("Grpc.Core.Tests")]
diff --git a/src/csharp/Grpc.Core/Server.cs b/src/csharp/Grpc.Core/Server.cs
index 8e818885d1..cbf77196cf 100644
--- a/src/csharp/Grpc.Core/Server.cs
+++ b/src/csharp/Grpc.Core/Server.cs
@@ -52,6 +52,7 @@ namespace Grpc.Core
         /// </summary>
         public const int PickUnusedPort = 0;
 
+        readonly GrpcEnvironment environment;
         readonly ServerSafeHandle handle;
         readonly object myLock = new object();
 
@@ -67,9 +68,10 @@ namespace Grpc.Core
         /// <param name="options">Channel options.</param>
         public Server(IEnumerable<ChannelOption> options = null)
         {
+            this.environment = GrpcEnvironment.GetInstance();
             using (var channelArgs = ChannelOptions.CreateChannelArgs(options))
             {
-                this.handle = ServerSafeHandle.NewServer(GetCompletionQueue(), channelArgs);
+                this.handle = ServerSafeHandle.NewServer(environment.CompletionQueue, channelArgs);
             }
         }
 
@@ -144,7 +146,7 @@ namespace Grpc.Core
                 shutdownRequested = true;
             }
 
-            handle.ShutdownAndNotify(GetCompletionQueue(), HandleServerShutdown);
+            handle.ShutdownAndNotify(HandleServerShutdown, environment);
             await shutdownTcs.Task;
             handle.Dispose();
         }
@@ -173,7 +175,7 @@ namespace Grpc.Core
                 shutdownRequested = true;
             }
 
-            handle.ShutdownAndNotify(GetCompletionQueue(), HandleServerShutdown);
+            handle.ShutdownAndNotify(HandleServerShutdown, environment);
             handle.CancelAllCalls();
             await shutdownTcs.Task;
             handle.Dispose();
@@ -208,7 +210,7 @@ namespace Grpc.Core
             {
                 if (!shutdownRequested)
                 {
-                    handle.RequestCall(GetCompletionQueue(), HandleNewServerRpc);
+                    handle.RequestCall(HandleNewServerRpc, environment);
                 }
             }
         }
@@ -225,7 +227,7 @@ namespace Grpc.Core
                 {
                     callHandler = new NoSuchMethodCallHandler();
                 }
-                await callHandler.HandleCall(method, call, GetCompletionQueue());
+                await callHandler.HandleCall(method, call, environment);
             }
             catch (Exception e)
             {
@@ -259,10 +261,5 @@ namespace Grpc.Core
         {
             shutdownTcs.SetResult(null);
         }
-
-        private static CompletionQueueSafeHandle GetCompletionQueue()
-        {
-            return GrpcEnvironment.ThreadPool.CompletionQueue;
-        }
     }
 }
diff --git a/src/csharp/Grpc.Core/Version.cs b/src/csharp/Grpc.Core/Version.cs
new file mode 100644
index 0000000000..972f495bd7
--- /dev/null
+++ b/src/csharp/Grpc.Core/Version.cs
@@ -0,0 +1,6 @@
+using System.Reflection;
+using System.Runtime.CompilerServices;
+
+// The current version of gRPC C#.
+[assembly: AssemblyVersion("0.6.0.*")]
+
diff --git a/src/csharp/Grpc.Core/packages.config b/src/csharp/Grpc.Core/packages.config
index fb7eaaeeda..6cdcdf2656 100644
--- a/src/csharp/Grpc.Core/packages.config
+++ b/src/csharp/Grpc.Core/packages.config
@@ -3,5 +3,5 @@
   <package id="grpc.dependencies.openssl.redist" version="1.0.2.2" targetFramework="net45" />
   <package id="grpc.dependencies.zlib.redist" version="1.2.8.9" targetFramework="net45" />
   <package id="Ix-Async" version="1.2.3" targetFramework="net45" />
-  <package id="Microsoft.Bcl.Immutable" version="1.0.34" targetFramework="net45" />
+  <package id="System.Collections.Immutable" version="1.1.36" targetFramework="net45" />
 </packages>
 \ No newline at end of file