.net 4.5中的msmq未处理的异步异常

Question

I've done some prototypes with MSMQ and faced weird behavior.

I have MSMQ service that sends data to some web service when there are messages incoming into queue. I'm turning off web service and expecting to see System.ServiceModel.ServerTooBusyException so that my messages would be returned to queue and will be sent later. I'm hosting MSMQ service in console application.

Now, if I'm sending data to web service synchronously then I get expected behavior. If I send data asynchronously my console application crashes with unhandled exceptions System.ServiceModel.ServerTooBusyException .

Here is pseudo code:

Console

AppDomain.CurrentDomain.UnhandledException += CurrentDomainOnUnhandledException;

using (MSMQServiceHost serviceHost = new MSMQServiceHost(typeof(Service1)))
{
    serviceHost.Open();

     Console.WriteLine("Press any key to stop service...");
     Console.ReadKey(true);
}

private static void CurrentDomainOnUnhandledException(object sender, UnhandledExceptionEventArgs unhandledExceptionEventArgs)
{
   MSMQ.Utils.LoggerHelper.GetLogger().ErrorFormat("CurrentDomainOnUnhandledException. {0}", unhandledExceptionEventArgs);
}

Service

[OperationBehavior(TransactionScopeRequired = true)]
public async  void GetData(int start, int end)
{
    try
    {
      using (WebServiceReference.Service1Client webClient = new WebServiceReference.Service1Client())
      {
        string data = await webClient.GetDataAsync(start);
        //string data = webClient.GetData(start);
        MSMQ.Utils.LoggerHelper.GetLogger().InfoFormat("Received info from web service. Data\t{0}", data);
    }
}
catch (Exception e)
{
    MSMQ.Utils.LoggerHelper.GetLogger().ErrorFormat("{1}\r\n{0}", e.Message, e.GetType().FullName);
    throw;
}

}

In case of synchronous call I get big list of logged errors, but application is not crashed. In case of asynchronous call I get the same list of logged errors plus the same number of CurrentDomainOnUnhandledException's (System.ServiceModel.ServerTooBusyException)

mscorlib.dll!System.Runtime.CompilerServices.AsyncMethodBuilderCore.ThrowAsync.AnonymousMethod__5(object state) Unknown mscorlib.dll!System.Threading.ExecutionContext.RunInternal(System.Threading.ExecutionContext executionContext, System.Threading.ContextCallback callback, object state, bool preserveSyncCtx) Unknown mscorlib.dll!System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext executionContext, System.Threading.ContextCallback callback, object state, bool preserveSyncCtx) Unknown mscorlib.dll!System.Threading.QueueUserWorkItemCallback.System.Threading.IThreadPoolWorkItem.ExecuteWorkItem() Unknown mscorlib.dll!System.Threading.ThreadPoolWorkQueue.Dispatch() Unknown

My awaitable is observable - I've subscribed to TaskScheduler.UnobservedTaskException and nothing there. How to properly use async in that case, so that I get all the benefits from APM and my application wouldn't crash?

Answer 1

I got it.

The problem is with async modifier in my service operation. Correct version:

[OperationBehavior(TransactionScopeRequired = true)]
public async Task GetData(int start, int end)
{
    try
    {
        await Task.Factory.StartNew(() =>
        {
            using (WebServiceReference.Service1Client webClient = new WebServiceReference.Service1Client())
            {
                 Task<string> data = GetWebClientData(start, webClient);
                 MSMQ.Utils.LoggerHelper.GetLogger().InfoFormat("Received info from web service. Data\t{0}", data.Result);
            }
        }
  }
  catch (Exception e)
  {
      MSMQ.Utils.LoggerHelper.GetLogger().ErrorFormat("{1}\r\n{0}", e.Message, e.GetType().FullName);
     throw;
  }
}

private static async Task<string> GetWebClientData(int start, WebServiceReference.Service1Client webClient)
{
    return await webClient.GetDataAsync(start);
}