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copied!<p>Out of the box, WCF does not support a service object pool. You need a custom <a href="http://msdn.microsoft.com/en-us/library/system.servicemodel.dispatcher.iinstanceprovider.aspx" rel="nofollow">IInstanceProvider</a>. In this scenario the WCF context mode would define when WCF requests a new object from the IInstanceProvider and the IInstanceProvider behavior would manage the pool. Setting the service to either PerInstance or PerSession could make sense depending on the usage. </p> <p>If you are using a Dependency Injection Container in your implementation such as <a href="http://docs.castleproject.org/Windsor.MainPage.ashx" rel="nofollow">Castle Windsor</a>, <a href="http://docs.structuremap.net/" rel="nofollow">StructureMap</a>, or MS Enterprise Library's <a href="http://msdn.microsoft.com/en-us/library/dd203101.aspx" rel="nofollow">Unity</a> then you can use the container's exsiting IInstanceProvider with a pooled lifestyle. All of those containers are reasonable (although I don't personally have much experience with having them manage object pools). </p> <p>My personal choice of container is Castle Windsor. In that case you would use Windsor's <a href="http://docs.castleproject.org/Windsor.WCF-Integration-Facility.ashx" rel="nofollow">WCF Integration Facility</a> and a <a href="http://docs.castleproject.org/Windsor.LifeStyles.ashx#Pooled_10" rel="nofollow">pooled lifestyle</a>.</p> <p>Here's a quick test console program that uses the Castle.Facilites.WcfIntegraion NuGet package. </p> <pre><code>using Castle.Facilities.WcfIntegration; using Castle.MicroKernel.Registration; using Castle.Windsor; using System; using System.Collections.Generic; using System.ServiceModel; using System.Threading.Tasks; namespace WCFWindsorPooledService { [ServiceContract] public interface ISimple { [OperationContract] void Default(string s); } public class SimpleService : ISimple { private static int CurrentIndex = 0; private int myIndex; public SimpleService() { // output which instance handled the call. myIndex = System.Threading.Interlocked.Increment(ref CurrentIndex); } public void Default(string s) { Console.WriteLine("Called #" + myIndex); System.Threading.Thread.Sleep(5); } } class PooledService { static void Main(string[] args) { Console.WriteLine("\n\n" + System.Reflection.MethodInfo.GetCurrentMethod().DeclaringType.Name); // define mapping of interfaces to implementation types in Windsor container. IWindsorContainer container = new WindsorContainer(); container.AddFacility<WcfFacility>() .Register(Component.For<SimpleService>().LifeStyle.PooledWithSize(2, 5)); var host = new Castle.Facilities.WcfIntegration.DefaultServiceHostFactory() .CreateServiceHost(typeof(SimpleService).AssemblyQualifiedName, new Uri[] { new Uri("http://localhost/Simple") }); host.Open(); ChannelFactory<ISimple> factory = new ChannelFactory<ISimple>(host.Description.Endpoints[0]); List<Task> tasks = new List<Task>(); for (int i = 0; i < 20; i++) { tasks.Add(Task.Run(() => { ISimple proxy = factory.CreateChannel(); proxy.Default("Hello"); ((ICommunicationObject)proxy).Shutdown(); })); } Task.WaitAll(tasks.ToArray()); ((ICommunicationObject)host).Shutdown(); container.Dispose(); } } public static class Extensions { static public void Shutdown(this ICommunicationObject obj) { try { obj.Close(); } catch (Exception ex) { Console.WriteLine("Shutdown exception: {0}", ex.Message); obj.Abort(); } } } } </code></pre> <p>I'm not going to pretend to understand all the rules of how Castle manages a pool, but a pool is clearly being used. The output is:</p> <pre><code>PooledService Called #1 Called #5 Called #2 Called #3 Called #4 Called #6 Called #7 Called #8 Called #7 Called #4 Called #2 Called #5 Called #1 Called #10 Called #6 Called #9 Called #4 Called #7 Called #1 Called #9 </code></pre>

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