Getting “A task was cancelled” while trying to create a document in DocumentDB

问题

When I try to create a document in my DocumentDB database using the following code, the code hangs where I call CreateDocumentAsync() and eventually gives me "A task was cancelled" error.

Any idea why?

public static async Task<Employee> CreateEmployee(Employee emp)
{
   try
   {
      using (client = new DocumentClient(new Uri(endPointUrl), authorizationKey))
      {
         //Get the database
         var database = await GetDatabaseAsync();

         //Get the Document Collection
         var collection = await GetCollectionAsync(database.SelfLink, "Employees");

         await client.CreateDocumentAsync(collection.SelfLink, emp);

         // Do something else with employee
      }
   }
   catch
   {
      // Handle error
   }

   return emp;
}

P.S. For brevity, I didn't include the code for GetDatabaseAsync() and GetCollectionsAsync() sections. Please note that the employee document IS created in my database. So, this code clearly connects to the DocumentDB database, finds the collection and creates the document.

Just not sure why it hangs and eventually returns the error.

***** Update ******

Here's the error details: A task was canceled.

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.Threading.Tasks.TaskCanceledException: A task was canceled. Source Error:

HttpResponseMessage response = await client.PostAsJsonAsync("api/hr/register", employee);

Stack Trace:

[TaskCanceledException: A task was canceled.]
   System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +10915395
   System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +52
   System.Runtime.CompilerServices.TaskAwaiter`1.GetResult() +24
   ConsumerWebApi.Controllers.<Index>d__0.MoveNext() in c:\Users\Sam\Documents\Visual Studio 2013\Projects\ConsumerWebApi\ConsumerWebApi\Controllers\HomeController.cs:36
   System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() +22
   System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +10915367
   System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +52
   System.Runtime.CompilerServices.TaskAwaiter.GetResult() +21
   System.Threading.Tasks.TaskHelpersExtensions.ThrowIfFaulted(Task task) +61
   System.Web.Mvc.Async.TaskAsyncActionDescriptor.EndExecute(IAsyncResult asyncResult) +114
   System.Web.Mvc.Async.<>c__DisplayClass37.<BeginInvokeAsynchronousActionMethod>b__36(IAsyncResult asyncResult) +66
   System.Web.Mvc.Async.WrappedAsyncResult`1.CallEndDelegate(IAsyncResult asyncResult) +47
   System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +135
   System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +102
   System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethod(IAsyncResult asyncResult) +49
   System.Web.Mvc.Async.AsyncInvocationWithFilters.<InvokeActionMethodFilterAsynchronouslyRecursive>b__3d() +117
   System.Web.Mvc.Async.<>c__DisplayClass46.<InvokeActionMethodFilterAsynchronouslyRecursive>b__3f() +323
   System.Web.Mvc.Async.<>c__DisplayClass33.<BeginInvokeActionMethodWithFilters>b__32(IAsyncResult asyncResult) +44
   System.Web.Mvc.Async.WrappedAsyncResult`1.CallEndDelegate(IAsyncResult asyncResult) +47
   System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +135
   System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +102
   System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethodWithFilters(IAsyncResult asyncResult) +50
   System.Web.Mvc.Async.<>c__DisplayClass2b.<BeginInvokeAction>b__1c() +72
   System.Web.Mvc.Async.<>c__DisplayClass21.<BeginInvokeAction>b__1e(IAsyncResult asyncResult) +185
   System.Web.Mvc.Async.WrappedAsyncResult`1.CallEndDelegate(IAsyncResult asyncResult) +42
   System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +132
   System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +56
   System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeAction(IAsyncResult asyncResult) +40
   System.Web.Mvc.Controller.<BeginExecuteCore>b__1d(IAsyncResult asyncResult, ExecuteCoreState innerState) +34
   System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) +70
   System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +138
   System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +59
   System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +40
   System.Web.Mvc.Controller.EndExecuteCore(IAsyncResult asyncResult) +44
   System.Web.Mvc.Controller.<BeginExecute>b__15(IAsyncResult asyncResult, Controller controller) +39
   System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) +62
   System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +138
   System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +59
   System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +40
   System.Web.Mvc.Controller.EndExecute(IAsyncResult asyncResult) +39
   System.Web.Mvc.Controller.System.Web.Mvc.Async.IAsyncController.EndExecute(IAsyncResult asyncResult) +39
   System.Web.Mvc.MvcHandler.<BeginProcessRequest>b__5(IAsyncResult asyncResult, ProcessRequestState innerState) +39
   System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) +70
   System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +138
   System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +59
   System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +40
   System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) +40
   System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest(IAsyncResult result) +38
   System.Web.CallHandlerExecutionStep.OnAsyncHandlerCompletion(IAsyncResult ar) +129

回答1:

The issue was caused by not getting async calls right. I was calling an async method i.e. CreateDocumentAsync() incorrectly.

I posted a separate question on async programming and the answers I got helped me troubleshoot the issue. Here's that post: Want to understand async

回答2:

I had a similar error thrown using one of DocumentClients async functions. I used await correctly for each call but then I found that this was caused by a proxy server interfering with the traffic. So for those working from inside a company network - consider checking this.

来源：https://stackoverflow.com/questions/27086097/getting-a-task-was-cancelled-while-trying-to-create-a-document-in-documentdb

标签

azure-cosmosdb