For experiments, I created a simple "Hello World" WCF service and client using .NET 4.5 on VS2012. The server is hosted on a console application and use net.tcp binding. I wrote the client code to send a burst of async requests (a total of 700 requests) to the server. Everything went fine until I turned ON the Reliable session feature of the service. After it is ON, the service suddenly ran very slow and it took almost a minute on my machine to complete the 700 requests. I tried to fine tune the Concurrency and Throttling parameters (see below) but it didn't help.
Does anyone know why this happen ? Is there anyway to avoid this ?
The slowness didn't happen if I turned OFF the Reliable session feature, or if I made the service call synchronous. So I think it may relate to the way WCF handles pending requests in WS-ReliableMessaging mode.
EDIT: Also this didn't happen when I chaned netTcpBinding to wsHttpBinding. This is very weird because in this case wsHttpBinding is much faster than netTcpBinding.
EDIT: Running Perfmon.exe on the server side shows that the "Thread Count" gradually increase from 8 to beyond 100 in the above case.
EDIT: Some measured throughput on my PC (local network). See that the performance of case 1 is very sluggish and practically useless.
- Async + NetTcpBinding/Reliable throughput -> approx. 14 call/s (70 ms/call)
- Async + WsHttp/Reliable throughput -> 7957 call/s (0.12 ms/call)
- Sync + NetTcpBinding/Reliable throughtput -> 3986 call/s (0.25 ms/call)
Below are the codes and configuration for the server and client I used in the experiments.
Server:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.ServiceModel;
using System.ServiceModel.Description;
[ServiceContract]
public interface IHelloService
{
[OperationContract(IsOneWay=false)]
string SayHello(string name);
}
[ServiceBehavior(ConcurrencyMode=ConcurrencyMode.Multiple, InstanceContextMode=InstanceContextMode.PerSession)]
public class HelloService : IHelloService
{
public string SayHello(string name) {
String s = string.Format("Hello {0}", name);
return s;
}
}
namespace WcfServer
{
class Program
{
static void Main(string[] args)
{
Uri baseAddress = new Uri("net.tcp://localhost:8080/hello");
using (ServiceHost host = new ServiceHost(typeof(HelloService), baseAddress)){
// Open and listen
host.Open();
Console.WriteLine("The service is ready at {0}", baseAddress);
Console.WriteLine("Press <Enter> to stop the service.");
Console.ReadLine();
// Close the ServiceHost.
host.Close();
}
}
}
}
Client:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.ServiceModel;
using WcfClient.WcfServer;
namespace WcfClient
{
class Program
{
static async Task PrintNameAsync(HelloServiceClient client, int cnt) {
string s = await client.SayHelloAsync(string.Format("-- {0} --", cnt));
Console.WriteLine(s);
}
static void Main(string[] args)
{
HelloServiceClient client = new HelloServiceClient("HelloService", "net.tcp://10.20.61.13:8080/hello");
List<Task> tasks = new List<Task>();
for(int i=0; i < 700; i++){
Task t = PrintNameAsync(client, i);
tasks.Add(t);
}
Task.WhenAll(tasks).Wait();
client.Close();
}
}
}
Server's App.config:
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<startup>
<supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5" />
</startup>
<system.serviceModel>
<bindings>
<netTcpBinding>
<binding name="HelloServiceBinding">
<reliableSession ordered="true" enabled="true" />
<security mode="None" />
</binding>
</netTcpBinding>
</bindings>
<behaviors>
<serviceBehaviors>
<behavior name="HelloServiceBehavior">
<serviceMetadata policyVersion="Policy15" />
<serviceDebug includeExceptionDetailInFaults="true" />
<serviceThrottling maxConcurrentCalls="1000" maxConcurrentSessions="1000"
maxConcurrentInstances="1000" />
</behavior>
</serviceBehaviors>
</behaviors>
<services>
<service behaviorConfiguration="HelloServiceBehavior" name="HelloService">
<endpoint address="net.tcp://localhost:8080/hello" binding="netTcpBinding"
bindingConfiguration="HelloServiceBinding" name="HelloService" contract="IHelloService" />
<endpoint address="mex" binding="mexTcpBinding" contract="IMetadataExchange" />
</service>
</services>
</system.serviceModel>
</configuration>
Client's App.config:
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<startup>
<supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5" />
</startup>
<system.serviceModel>
<bindings>
<netTcpBinding>
<binding name="HelloServiceBinding" sendTimeout="00:01:00">
<reliableSession enabled="true" />
<security mode="None" />
</binding>
</netTcpBinding>
</bindings>
<client>
<endpoint address="net.tcp://localhost:8080/hello" binding="netTcpBinding"
bindingConfiguration="HelloServiceBinding" contract="WcfServer.IHelloService"
name="HelloService">
</endpoint>
</client>
</system.serviceModel>
</configuration>