NServiceBus和实体框架导致异常-基础提供程序在打开时失败

Question

I am having trouble understanding and troubleshooting the following exception in an endpoint. I have seen many posts on this error on SO, yet no question reflected the specific scenario in our application.

This happens intermittently , and I previously attempted to resolve this by increasing both the connection and command timeout for Entity Framework.

The endpoint and database are running on the same machine . The error does not happen very often, only maybe for larger updates or deletes.

As a side note, I routinely get the "The underlying provider failed on Open" while debugging . I always believed this was because I spent too much time on a breakpoint, and the connection was closed when I continue.

I wanted to ask what the best practice is for using/injecting an Entity Framework DbContext in an NServiceBus endpoint ? Is it best to inject the context via NSB's dependency injection? Like so:

public class ConfigureDependencyInjection : INeedInitialization
{
    public void Customize( BusConfiguration configuration )
    {
        configuration.RegisterComponents( reg =>
        {
            reg.ConfigureComponent<MyDbContext>( DependencyLifecycle.InstancePerCall );
        } );
    }
}

or should I not be using this, but instead instantiate the context as needed:

using (var context = new MyDbContext()) { ... }

The message that is handled here is one single physical message, very straight forward -- which is why I opted for DependencyLifecycle.InstancePerCall.

But when is DependencyLifecycle.InstancePerUnitOfWork the correct option when using Entity Framework?

What can I do to better debug this error?

Here is the exception, and stack:

The underlying provider failed on Open.
The operation is not valid for the state of the transaction.

at System.Transactions.TransactionState.EnlistPromotableSinglePhase(InternalTransaction tx, IPromotableSinglePhaseNotification promotableSinglePhaseNotification, Transaction atomicTransaction, Guid promoterType)
at System.Transactions.Transaction.EnlistPromotableSinglePhase(IPromotableSinglePhaseNotification promotableSinglePhaseNotification, Guid promoterType)
at System.Transactions.Transaction.EnlistPromotableSinglePhase(IPromotableSinglePhaseNotification promotableSinglePhaseNotification)
at System.Data.SqlClient.SqlInternalConnection.EnlistNonNull(Transaction tx)
at System.Data.SqlClient.SqlInternalConnection.Enlist(Transaction tx)
at System.Data.ProviderBase.DbConnectionInternal.ActivateConnection(Transaction transaction)
at System.Data.ProviderBase.DbConnectionPool.PrepareConnection(DbConnection owningObject, DbConnectionInternal obj, Transaction transaction)
at System.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, UInt32 waitForMultipleObjectsTimeout, Boolean allowCreate, Boolean onlyOneCheckConnection, DbConnectionOptions userOptions, DbConnectionInternal& connection)
at System.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal& connection)
at System.Data.ProviderBase.DbConnectionFactory.TryGetConnection(DbConnection owningConnection, TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal oldConnection, DbConnectionInternal& connection)
at System.Data.ProviderBase.DbConnectionInternal.TryOpenConnectionInternal(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions)
at System.Data.SqlClient.SqlConnection.TryOpenInner(TaskCompletionSource`1 retry)
at System.Data.SqlClient.SqlConnection.TryOpen(TaskCompletionSource`1 retry)
at System.Data.SqlClient.SqlConnection.Open()
at System.Data.Entity.Infrastructure.Interception.InternalDispatcher`1.Dispatch[TTarget,TInterceptionContext](TTarget target, Action`2 operation, TInterceptionContext interceptionContext, Action`3 executing, Action`3 executed)
at System.Data.Entity.Infrastructure.Interception.DbConnectionDispatcher.Open(DbConnection connection, DbInterceptionContext interceptionContext)
at System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy.<>c__DisplayClass1.<Execute>b__0()
at System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy.Execute[TResult](Func`1 operation)
at System.Data.Entity.Core.EntityClient.EntityConnection.Open()
--- End of inner exception stack trace ---
at System.Data.Entity.Core.EntityClient.EntityConnection.Open()
at System.Data.Entity.Core.Objects.ObjectContext.EnsureConnection(Boolean shouldMonitorTransactions)
at System.Data.Entity.Core.Objects.ObjectContext.ExecuteInTransaction[T](Func`1 func, IDbExecutionStrategy executionStrategy, Boolean startLocalTransaction, Boolean releaseConnectionOnSuccess)
at System.Data.Entity.Core.Objects.ObjectQuery`1.<>c__DisplayClass7.<GetResults>b__5()
at System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy.Execute[TResult](Func`1 operation)
at System.Data.Entity.Core.Objects.ObjectQuery`1.GetResults(Nullable`1 forMergeOption)
at System.Data.Entity.Core.Objects.DataClasses.EntityCollection`1.Load(List`1 collection, MergeOption mergeOption)
at System.Data.Entity.Core.Objects.DataClasses.RelatedEnd.DeferredLoad()
at System.Data.Entity.Core.Objects.Internal.LazyLoadBehavior.LoadProperty[TItem](TItem propertyValue, String relationshipName, String targetRoleName, Boolean mustBeNull, Object wrapperObject)
at System.Data.Entity.Core.Objects.Internal.LazyLoadBehavior.<>c__DisplayClass7`2.<GetInterceptorDelegate>b__1(TProxy proxy, TItem item)
at System.Data.Entity.DynamicProxies.JournalTransaction_4CAE8D09C8D2614F98562EAA87E63CE3B6D4E9A6DEC760505C0C7C7C42295ECE.get_TransactionItems()

This is for NSB 5.2.14, though earlier versions show the same behaviour.

Thanks for your help.

Answer 1

John, this error can also occur when the connection has been opened and closed already, perhaps this is the problem. But as it seems it tries to enlist in a distributed transaction and is failing there. And if it is while debugging, how long are you debugging? It might be that the connection timed out and that it retries to open a closed connection? What is your connection timeout? What transport are you using? Is MSDTC on? And do you have any idea when it starts failing? Is it a different message or the same?

Not sure how you're MyDbContext behaves, but mine always look like this:

public class MyDbContext : DbContext
{
  public MyDbContext : base("MyConnectionString")
  {
  }
}

That way I make sure it picks a specific connectionstring and I know I won't forget it, and what not.