如何捕获此 SignalR 异常

Question

我有一个 ASP.NET Web Api，它使用 SignalR 将实时数据传送到移动客户端。一切运行良好，但我在跟踪日志中看到异常，我似乎无法捕获或处理此异常：

Application: 2014-05-20T03:24:57  PID[2088] Warning     SignalR exception thrown by Task: System.AggregateException: One or more errors occurred. ---> System.Web.HttpException: The remote host closed the connection. The error code is 0x800704CD.
Application:    at System.Web.Hosting.IIS7WorkerRequest.RaiseCommunicationError(Int32 result, Boolean throwOnDisconnect)
Application:    at System.Web.Hosting.IIS7WorkerRequest.ExplicitFlush()
Application:    at System.Web.HttpResponse.Flush(Boolean finalFlush, Boolean async)
Application:    at System.Web.HttpResponse.Flush()
Application:    at System.Web.HttpWriter.WriteFromStream(Byte[] data, Int32 offset, Int32 size)
Application:    at System.Web.HttpResponseStream.Write(Byte[] buffer, Int32 offset, Int32 count)
Application:    at Microsoft.Owin.Host.SystemWeb.CallStreams.OutputStream.Write(Byte[] buffer, Int32 offset, Int32 count)
Application:    at Microsoft.AspNet.SignalR.Owin.ServerResponse.Write(ArraySegment`1 data)
Application:    at Microsoft.AspNet.SignalR.Infrastructure.BinaryTextWriter.<.ctor>b__4(ArraySegment`1 data, Object state)
Application:    at Microsoft.AspNet.SignalR.Infrastructure.BufferTextWriter.ChunkedWriter.Flush(Byte[] byteBuffer, Boolean flushEncoder)
Application:    at Microsoft.AspNet.SignalR.Infrastructure.BufferTextWriter.ChunkedWriter.Flush(Boolean flushEncoder)
Application:    at Microsoft.AspNet.SignalR.Infrastructure.BufferTextWriter.Flush()
Application:    at Microsoft.AspNet.SignalR.Transports.ServerSentEventsTransport.PerformKeepAlive(Object state)
Application:    at Microsoft.AspNet.SignalR.Transports.ServerSentEventsTransport.<KeepAlive>b__0(Object state)
Application:    at Microsoft.AspNet.SignalR.Infrastructure.TaskQueue.<Enqueue>b__1(Func`2 next, Object nextState)
Application:    at Microsoft.AspNet.SignalR.TaskAsyncHelper.FromMethod[T1,T2](Func`3 func, T1 arg1, T2 arg2)
Application:    --- End of inner exception stack trace ---
Application: ---> (Inner Exception #0) System.Web.HttpException (0x800704CD): The remote host closed the connection. The error code is 0x800704CD.
Application:    at System.Web.Hosting.IIS7WorkerRequest.RaiseCommunicationError(Int32 result, Boolean throwOnDisconnect)
Application:    at System.Web.Hosting.IIS7WorkerRequest.ExplicitFlush()
Application:    at System.Web.HttpResponse.Flush(Boolean finalFlush, Boolean async)
Application:    at System.Web.HttpResponse.Flush()
Application:    at System.Web.HttpWriter.WriteFromStream(Byte[] data, Int32 offset, Int32 size)
Application:    at System.Web.HttpResponseStream.Write(Byte[] buffer, Int32 offset, Int32 count)
Application:    at Microsoft.Owin.Host.SystemWeb.CallStreams.OutputStream.Write(Byte[] buffer, Int32 offset, Int32 count)
Application:    at Microsoft.AspNet.SignalR.Owin.ServerResponse.Write(ArraySegment`1 data)
Application:    at Microsoft.AspNet.SignalR.Infrastructure.BinaryTextWriter.<.ctor>b__4(ArraySegment`1 data, Object state)
Application:    at Microsoft.AspNet.SignalR.Infrastructure.BufferTextWriter.ChunkedWriter.Flush(Byte[] byteBuffer, Boolean flushEncoder)
Application:    at Microsoft.AspNet.SignalR.Infrastructure.BufferTextWriter.ChunkedWriter.Flush(Boolean flushEncoder)
Application:    at Microsoft.AspNet.SignalR.Infrastructure.BufferTextWriter.Flush()
Application:    at Microsoft.AspNet.SignalR.Transports.ServerSentEventsTransport.PerformKeepAlive(Object state)
Application:    at Microsoft.AspNet.SignalR.Transports.ServerSentEventsTransport.<KeepAlive>b__0(Object state)
Application:    at Microsoft.AspNet.SignalR.Infrastructure.TaskQueue.<Enqueue>b__1(Func`2 next, Object nextState)
Application:    at Microsoft.AspNet.SignalR.TaskAsyncHelper.FromMethod[T1,T2](Func`3 func, T1 arg1, T2 arg2)<---

我的所有代码都包含在 try/catch 语句中，并且我有一个使用 TaskScheduler.UnobservedTaskException 定义的未观察到的异常处理程序。如果我能抓住它，我可以展平聚合异常并单独处理每个异常。

有谁知道我如何捕捉或处理这个异常？它似乎每隔几分钟就会发生一次。在此先感谢 - 我一直在努力解决这个问题。

Answer 1

您应该可以使用HttpApplication.Error 来捕捉它，更多详情请点击此处：

Processing Unhandled Exceptions

但令我惊讶的是，您的 catch 块都没有被触发。您确定要包装每个 Task 吗？您可能想从here 尝试类似task.WithObservation()。