WCF 轮询双工会话

Question

我有一个 Silverlight 客户端，它尝试创建会话，但服务器没有响应（客户端抛出超时异常）。在服务器日志中我发现：

<E2ETraceEvent xmlns="http://schemas.microsoft.com/2004/06/E2ETraceEvent">
<System xmlns="http://schemas.microsoft.com/2004/06/windows/eventlog/system">
<EventID>0</EventID>
<Type>3</Type>
<SubType Name="Warning">0</SubType>
<Level>4</Level>
<TimeCreated SystemTime="2011-03-01T15:47:17.3951653Z" />
<Source Name="System.ServiceModel.PollingDuplex" />
<Correlation ActivityID="{00000000-0000-0000-0000-000000000000}" />
<Execution ProcessName="w3wp" ProcessID="3820" ThreadID="17" />
<Channel />
<Computer>VM662</Computer>
</System>
<ApplicationData>
<TraceData>
<DataItem>
<TraceRecord xmlns="http://schemas.microsoft.com/2004/10/E2ETraceEvent/TraceRecord" Severity="Warning">
<TraceIdentifier>http://msdn.microsoft.com/ru-RU/library/System.ServiceModel.PollingDuplex.ListenerClosed.aspx</TraceIdentifier>
<Description>The service no longer accepts new sessions. An http error was returned.</Description>
<AppDomain>/LM/W3SVC/1/ROOT-1-129434680323302677</AppDomain>
<Source>System.ServiceModel.Channels.PollingDuplexChannelListener/40535505</Source>
<ExtendedData xmlns="http://schemas.microsoft.com/2006/08/ServiceModel/PollingDuplexTraceRecord">
<clientAddress>http://docs.oasis-open.org/ws-rx/wsmc/200702/anonymous?id=1a9b0998-7fa0-4c53-8268-d4db5e8fad61</clientAddress>
<serverAddress>http://porn.com/getgirls.svc</serverAddress>
<sessionId>3d21efa1-1204-433a-8881-06cd6da7de60</sessionId>
<HttpStatusCode>NotFound</HttpStatusCode>
</ExtendedData>
</TraceRecord>
</DataItem>
</TraceData>
<System.Diagnostics xmlns="http://schemas.microsoft.com/2004/08/System.Diagnostics">
<LogicalOperationStack></LogicalOperationStack>
<Timestamp>2545401989404</Timestamp>
</System.Diagnostics>
</ApplicationData>
</E2ETraceEvent>

这是什么意思？为什么具有轮询双工绑定的 WCF 服务无法“接受新会话”？

更新： 服务器有大约20个并发会话请求，其中大多数都失败了。但当我开始另一次测试时，一切正常。此问题时常发生，重新启动服务器通常可以解决此问题。 服务器配置：

<system.diagnostics>
    <sources>
        <source name="System.ServiceModel.PollingDuplex" switchValue="Information">

            <listeners>

                <add type="System.Diagnostics.DefaultTraceListener" name="Default"/>

                <add name="ServiceModelTraceListener" />
                <add name="ServiceModelMessageLoggingListener" />

            </listeners>
        </source>
        <!--<source name="System.ServiceModel.MessageLogging" switchValue="Warning, ActivityTracing">
            <listeners>
                <add type="System.Diagnostics.DefaultTraceListener" name="Default"/>
                <add name="ServiceModelMessageLoggingListener"/>
            </listeners>
        </source>
        <source name="System.ServiceModel" switchValue="Warning, ActivityTracing" propagateActivity="true">
            <listeners>
                <add type="System.Diagnostics.DefaultTraceListener" name="Default"/>
                <add name="ServiceModelTraceListener"/>
            </listeners>
        </source>-->
    </sources>
    <sharedListeners>
        <add initializeData="c:\pdt_logs\messages.svclog" type="System.Diagnostics.XmlWriterTraceListener, System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" name="ServiceModelMessageLoggingListener" traceOutputOptions="LogicalOperationStack, DateTime, Timestamp" />
        <add initializeData="c:\pdt_logs\web_tracelog.svclog" type="System.Diagnostics.XmlWriterTraceListener, System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" name="ServiceModelTraceListener" traceOutputOptions="Timestamp" />
    </sharedListeners>
    <trace autoflush="true" />
</system.diagnostics>

<system.web>
    <compilation targetFramework="4.0" />
</system.web>

<system.serviceModel>
    <diagnostics>
        <messageLogging logEntireMessage="true" logMessagesAtServiceLevel="true" logMessagesAtTransportLevel="true" />
    </diagnostics>
    <extensions>
        <bindingElementExtensions>
            <add name="pollingDuplex" type="System.ServiceModel.Configuration.PollingDuplexElement, System.ServiceModel.PollingDuplex, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"/>
        </bindingElementExtensions>
    </extensions>

    <bindings>
        <customBinding>
            <binding name="PollingDuplexBinding" >
                <binaryMessageEncoding>
                    <readerQuotas maxArrayLength="16777216" maxBytesPerRead="16777216" maxDepth="16777216"
                                          maxNameTableCharCount="16777216" maxStringContentLength="16777216"/>
                </binaryMessageEncoding>
                <pollingDuplex maxPendingSessions="100"
             maxPendingMessagesPerSession="250" inactivityTimeout="24.20:31:23.6470000"/>

                <httpTransport maxBufferSize="16777216"
                                 maxReceivedMessageSize="16777216" />
            </binding>
        </customBinding>



    </bindings>

    <services>
        <service name="PollingDuplexApplication.Services.TestService" behaviorConfiguration="ServiceBehavior">
            <endpoint address=""
                              binding="customBinding"
                              contract="PollingDuplexApplication.Services.TestService"
                              bindingConfiguration="PollingDuplexBinding">
            </endpoint>
            <endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange"/>
        </service>
    </services>

    <behaviors>
        <serviceBehaviors>
            <behavior name="ServiceBehavior">
                <serviceMetadata httpGetEnabled="true"/>
                <serviceDebug includeExceptionDetailInFaults="true"/>
                <serviceThrottling  maxConcurrentCalls="2048" maxConcurrentSessions="2048" maxConcurrentInstances="2048"/>
                <dataContractSerializer maxItemsInObjectGraph="16777216"/>
            </behavior>
        </serviceBehaviors>
    </behaviors>
    <serviceHostingEnvironment multipleSiteBindingsEnabled="true" />
</system.serviceModel>

<system.webServer>
    <modules runAllManagedModulesForAllRequests="true"/>
  </system.webServer>

Answer 1

您使用什么轮询双工模式？我遇到过类似的问题，服务器出现多条消息问题。

解决方案是将我的 PollingDuplexMode 更改为 SingleMessagePerPoll。 WCF 似乎在 MultipleMessagesPerPoll 方面存在一些问题。

您可以在构建绑定时更改模式：

new PollingDuplexHttpBinding(PollingDuplexMode.SingleMessagePerPoll);

或者在配置文件中。

Answer 2

我想到了两件事，我应该注意的是，我没有使用 Silverlight 完成此操作，仅使用常规 WCF 完成此操作。您可以激活的并发会话数量是有限制的。我认为开箱即用的限制是 16。您可以在此答案中查看如何更改它

使用 WSHttpBinding 时，WCF 并发请求会在服务器上堆积，

或者您可以在 svc 文件编辑器中更改它。如果您在代码中定义服务器，则需要在绑定中找到该选项，但我一时记不起这一点。

您还可能在服务器上进行备份。我建议（在检查您的锁定模型之后）将服务合同标记为 Concurrency=Multiple