WCF: StreamedResponse throws Timeout after a few processed calls

i'm trying to set up an WCF-Web that returns data from the database as Streamed Response to the Client. The method returns 45.000 Items currently.

My problem is, that when i try to call this method a couple of times, some requests will succeed, while the next call dies with an TimeoutException - seems like the client is not able to establish a new connecton to the host. If i change the TransferMode to "Buffered" it will work like intended.

The amount of successfully processed calls can be increased by increasing the System.Net.ServicePointManager.DefaultConnectionLimit to a larger Number.

It seems to me, that the client does not close the connection? But why only in StreamedResponse mode? Where's the mistake? Any idea?

Source:

public static void DoCall() {
        var factory = new ChannelFactory<ICacheService>("ICacheService", new EndpointAddress(...));
        ICacheService service = factory.CreateChannel();
        try
        {

        var itemsMessage = service.DoStreaming(
            Message.CreateMessage(MessageVersion.Soap11, "DoStreaming", "SomeArgumnt")
        );

        foreach (Item item in GetAllItems(itemsMessage))
        {
            ...
        }

        var serviceChannel = ((IServiceChannel) service);
        if (serviceChannel.State != System.ServiceModel.CommunicationState.Faulted)
            serviceChannel.Close();

        itemsMessage.Close();
        ((IServiceChannel)service).Close();         

        }
        catch (Exception ex)
        {
            ((IServiceChannel) service).Abort();
        }   

        factory.Close();            
    }

    private static IEnumerable<Item> GetAllItems(System.ServiceModel.Channels.Message message)
    {
        XmlReader reader = message.GetReaderAtBodyContents();
        if (reader.LocalName != "results")
        {
            throw new Exception("The service returned an invalid message");
        }

        XmlSerializer serializer = new XmlSerializer(typeof(Item));
        reader.ReadStartElement("results");

        while (!reader.EOF && reader.LocalName == "Item")
        {
            yield return (Item)serializer.Deserialize(reader);
        }

        reader.ReadEndElement();
    }

Client-Binding:

<binding
               name="BasicHttpBinding_ICacheService"
               openTimeout="00:01:00"
               receiveTimeout="00:01:00"
               sendTimeout="00:10:00"
               maxReceivedMessageSize="1000000000"
               transferMode="Buffered"
            >
           <readerQuotas
               maxDepth="2147483647"
               maxStringContentLength="2147483646"
               maxArrayLength="2147483647"
               maxBytesPerRead="2147483647"
               maxNameTableCharCount="2147483开发者_运维知识库647"
                />
           <security mode="None">
               <transport clientCredentialType="None" proxyCredentialType="None" realm="" />
               <message clientCredentialType="UserName" algorithmSuite="Default" />
           </security>
       </binding>