WCF – ServiceThrottlingBehavior

﹏ヽ暗。殇╰゛Y 2022-08-01 12:19 167阅读 0赞

# #

ServiceThrottlingBehavior 允许我们为服务宿主设置一个  
"安全阀"，用于避免恶意或意外的大量并发摧毁服务器。我们可以设置同一时刻最多可以创建的服务实例数量，最多可创建的会话数量，以及所有服务实例并发调  
用总量。当超出这些阀值时，WCF 会让客户端调用进入一个等待队列，直至获取执行授权。如果等待超时，客户端代理会触发  
TimeoutException 异常。

ServiceThrottlingBehavior 的三个属性参数分别对应上面所说的三种情况。

*  MaxConcurrentInstances : 设置同一时刻服务上下文实例的最大数量。( 限制服务并发实例数量。缺省 Int32.MaxValue。)
 *  MaxConcurrentSessions : 设置同一时刻可以接受的最大会话数量。(限制并发会话数量。缺省 10。)
 *  MaxConcurrentCalls : 设置 ServiceHost 消息并发处理的最大值。 (限制所有服务实例并发调用总数量，缺省 64。)

下面我们写个例子来验证一下，我们将 MaxConcurrentInstances 设置为 1，用多线程模拟 5 个客户端进行并发。

**测试原型**

\[ServiceContract(SessionMode = SessionMode.Required)\]  
public interface IContract  
\{  
  \[OperationContract\]  
  void Test();  
\}

\[ServiceBehavior(InstanceContextMode = InstanceContextMode.PerSession)\]  
public class MyService : IContract, IDisposable  
\{  
  public MyService()  
  \{  
    Console.WriteLine("Constructor:\{0\}", OperationContext.Current.SessionId);  
  \}

public void Dispose()  
  \{  
    Console.WriteLine("Dispose...");  
  \}

public void Test()  
  \{  
    Console.WriteLine("Test:\{0\}", OperationContext.Current.SessionId);  
    Thread.Sleep(2000);  
  \}  
\}

public class WcfTest  
\{  
  public static void Test()  
  \{  
    AppDomain.CreateDomain("Server").DoCallBack(delegate  
    \{  
      ServiceHost host = new ServiceHost(typeof(MyService), new Uri("http://localhost:8080/MyService"));  
      host.AddServiceEndpoint(typeof(IContract), new WSHttpBinding(), "");  
      host.Open();  
    \});

for (int i = 0; i < 5; i++)  
    \{  
      new Thread(delegate()  
      \{  
        IContract channel = ChannelFactory<IContract>.CreateChannel(new WSHttpBinding(),   
          new EndpointAddress("http://localhost:8080/MyService"));  
        using (channel as IDisposable)  
        \{  
          channel.Test();  
        \}  
      \}).Start();  
    \}  
  \}  
\}

输出：  
Constructor:urn:uuid:6014cb54-9f44-4d16-8488-6841b682030b  
Constructor:urn:uuid:7d6ca245-7d10-48ec-8619-d332cdb567b9  
Constructor:urn:uuid:f64f973d-7361-4eea-8fbd-5244a4306957  
Constructor:urn:uuid:ce8c2810-fc73-4419-aa65-e41617e416c4  
Test:urn:uuid:ce8c2810-fc73-4419-aa65-e41617e416c4  
Test:urn:uuid:6014cb54-9f44-4d16-8488-6841b682030b  
Test:urn:uuid:f64f973d-7361-4eea-8fbd-5244a4306957  
Test:urn:uuid:7d6ca245-7d10-48ec-8619-d332cdb567b9  
Constructor:urn:uuid:333d06db-9751-4e35-be7a-1ea791c31da4  
Test:urn:uuid:333d06db-9751-4e35-be7a-1ea791c31da4  
Dispose...  
Dispose...  
Dispose...  
Dispose...  
Dispose...

**并发控制**

AppDomain.CreateDomain("Server").DoCallBack(delegate  
\{  
  ServiceHost host = new ServiceHost(typeof(MyService), new Uri("http://localhost:8080/MyService"));  
  host.AddServiceEndpoint(typeof(IContract), new WSHttpBinding(), "");

ServiceThrottlingBehavior throttling = new ServiceThrottlingBehavior();  
  throttling.MaxConcurrentInstances = 1;  
  host.Description.Behaviors.Add(throttling);

host.Open();  
\});

using (channel as IDisposable)  
    \{  
      channel.Test();  
    \}  
  \}).Start();  
\}

输出：  
Constructor:urn:uuid:aadd2b1f-b394-4039-a680-321c8d3f01ef  
Test:urn:uuid:aadd2b1f-b394-4039-a680-321c8d3f01ef  
Dispose...  
Constructor:urn:uuid:d26243d1-9157-4b6d-b074-a99a6aba96b3  
Test:urn:uuid:d26243d1-9157-4b6d-b074-a99a6aba96b3  
Dispose...  
Constructor:urn:uuid:4d01794b-efc3-4ae7-b8e2-842f6b0fa1fc  
Test:urn:uuid:4d01794b-efc3-4ae7-b8e2-842f6b0fa1fc  
Dispose...  
Constructor:urn:uuid:e63170f1-2d37-434c-8ee4-10a714a3bb9e  
Test:urn:uuid:e63170f1-2d37-434c-8ee4-10a714a3bb9e  
Dispose...  
Constructor:urn:uuid:a28e13a6-0fdf-4d8b-9c1b-fc45ef7d0f28  
Test:urn:uuid:a28e13a6-0fdf-4d8b-9c1b-fc45ef7d0f28  
Dispose...

对比前后输出的结果，我们可以很清楚的看到并发控制带来的效果。其他两个参数的使用方法类似，本文不做进一步描述。