Question

我的应用程序工作得非常好一段时间然后突然间我在每个页面上遇到这个非常奇怪的错误，

[InvalidOperationException: Connection cannot be changed while async operation is in progress.]

System.Data.SqlClient.SqlCommand.set_Connection(SqlConnection value) +5340612
   InvertedSoftware.DataBlock.<ExecuteReaderAsync>d__7.MoveNext() +679
   System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +93
   System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +52
   XX.Data.Repositories.<GetAllByMerchantIdAsync>d__1f.MoveNext() in c:\Users\XX.cs:90
   System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +93
   System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +52
   Namespace.Controllers.<Index>d__2.MoveNext() in c:\Users\XX.cs.cs:44
   System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +93
   System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +52
   System.Web.Mvc.Async.TaskAsyncActionDescriptor.EndExecute(IAsyncResult asyncResult) +84
   System.Web.Mvc.Async.<>c__DisplayClass37.<BeginInvokeAsynchronousActionMethod>b__36(IAsyncResult asyncResult) +17
   System.Web.Mvc.Async.WrappedAsyncResult`1.CallEndDelegate(IAsyncResult asyncResult) +10
   System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +48
   System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethod(IAsyncResult asyncResult) +32
   System.Web.Mvc.Async.AsyncInvocationWithFilters.<InvokeActionMethodFilterAsynchronouslyRecursive>b__3f() +50
   System.Web.Mvc.Async.<>c__DisplayClass48.<InvokeActionMethodFilterAsynchronouslyRecursive>b__41() +225
   System.Web.Mvc.Async.<>c__DisplayClass48.<InvokeActionMethodFilterAsynchronouslyRecursive>b__41() +225
   System.Web.Mvc.Async.<>c__DisplayClass33.<BeginInvokeActionMethodWithFilters>b__32(IAsyncResult asyncResult) +10
   System.Web.Mvc.Async.WrappedAsyncResult`1.CallEndDelegate(IAsyncResult asyncResult) +10
   System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +48
   System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethodWithFilters(IAsyncResult asyncResult) +34
   System.Web.Mvc.Async.<>c__DisplayClass2b.<BeginInvokeAction>b__1c() +26
   System.Web.Mvc.Async.<>c__DisplayClass21.<BeginInvokeAction>b__1e(IAsyncResult asyncResult) +100
   System.Web.Mvc.Async.WrappedAsyncResult`1.CallEndDelegate(IAsyncResult asyncResult) +10
   System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +48
   System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeAction(IAsyncResult asyncResult) +27
   System.Web.Mvc.Controller.<BeginExecuteCore>b__1d(IAsyncResult asyncResult, ExecuteCoreState innerState) +13
   System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) +36
   System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +53
   System.Web.Mvc.Controller.EndExecuteCore(IAsyncResult asyncResult) +39
   System.Web.Mvc.Controller.<BeginExecute>b__15(IAsyncResult asyncResult, Controller controller) +12
   System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) +28
   System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +53
   System.Web.Mvc.Controller.EndExecute(IAsyncResult asyncResult) +29
   System.Web.Mvc.Controller.System.Web.Mvc.Async.IAsyncController.EndExecute(IAsyncResult asyncResult) +10
   System.Web.Mvc.MvcHandler.<BeginProcessRequest>b__5(IAsyncResult asyncResult, ProcessRequestState innerState) +21
   System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) +36
   System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +53
   System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) +31
   System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest(IAsyncResult result) +9
   System.Web.CallHandlerExecutionStep.OnAsyncHandlerCompletion(IAsyncResult ar) +129

注意我正在使用MVC 5.1和Azure网站。我的Azure网站与Sql Azure交谈。这是我抛出错误的代码，

  using (var reader = await SqlHelper.ExecuteReaderAsync(_connectionString, CommandType.StoredProcedure, "MySP", parameters))

我正在使用此SqlHelper.cs

Answer 1

SqlHelper类有一个错误。 ExecuteReader(Async)返回一个开放的阅读器。它立即将用于获取该读取器的命令放回池中。这意味着现在存在竞争条件：可以使用读者，而另一个线程可以突变基础命令。这就是SqlCommand.set_Connection投掷的原因。

无论如何，汇集SqlCommand并不是一个好主意，因为命令创建起来非常便宜。池中的同步可能比设置新命令更昂贵。

异步操作正在进行时无法更改连接

1 个答案: