回滚事务时出现异常 - 连接已关闭?

Exceptions when rolling back a transaction - connection already closed?(回滚事务时出现异常 - 连接已关闭?)

问题描述

使用 Entity Framework 6.0.0，我在关闭事务时看到异常.

Using Entity Framework 6.0.0, I'm seeing an exception when closing a transaction.

我们一直在对表进行并发更改时遇到问题，所以我将它包装在一个事务中，现在我在回滚时遇到异常.

We'd been having problems with concurrent changes to the table, so I wrapped it in a transaction, and now I'm getting exceptions on rollback.

代码:

public LockInfo getSharedLock(string jobid)
{
    using (var myDbContext = new MyDbContext())
    {
        using (var transaction = myDbContext.Database.BeginTransaction())
        {
            try
            {
                this.logger.log("Attempting to get shared lock for {0}", jobid);

                var mylocks =
                    myDbContext.joblocks.Where(j => j.customerid == this.userContext.customerid)
                        .Where(j => j.jobid == jobid)
                        .Where(j => j.operatorid == this.userContext.operatorid);

                var exclusiveLock = mylocks.FirstOrDefault(
                    j => j.lockstatus == LockInfo.LockState.Exclusive);
                if (exclusiveLock != null)
                {
                    this.logger.log("{0} already had exclusive lock, ignoring", jobid);
                    return LockInfo.populate(exclusiveLock);
                }

                var sharedLock = mylocks.FirstOrDefault(
                    j => j.lockstatus == LockInfo.LockState.Shared);
                if (sharedLock != null)
                {
                    this.logger.log("{0} already had shared lock, ignoring", jobid));
                    sharedLock.lockdt = DateTime.Now;
                    myDbContext.SaveChanges();

                    return LockInfo.populate(sharedLock);
                }

                var joblock = new joblock
                {
                    customerid = this.userContext.customerid,
                    operatorid = this.userContext.operatorid,
                    jobid = jobid,
                    lockstatus = LockInfo.LockState.Shared,
                    sharedLock.lockdt = DateTime.Now
                };

                myDbContext.joblocks.Add(joblock);
                myDbContext.SaveChanges();
                transaction.Commit();

                this.logger.log("Obtained shared lock for {0}", jobid);
                return LockInfo.populate(joblock);
            }
            catch (Exception ex)
            {
                transaction.Rollback();
                this.logger.logException(ex, "Exception in getSharedLock("{0}")", jobid);
                throw;
            }
        }
    }
}

您可以在上面的代码中看到日志记录.我们也在数据库中启用了日志记录.日志跟踪:

You can see the logging, in the code above. We have logging enabled in the database, too. The log trace:

===================
NORMAL    TicketLockController.getLock("AK2015818002WL")
===================
SQL    Opened connection at 9/22/2015 2:47:49 PM -05:00
===================
SQL    Started transaction at 9/22/2015 2:47:49 PM -05:00
===================
NORMAL    Attempting to get shared lock for AK2015818002WL
===================
SQL    SELECT TOP (1) [Extent1].[customerid] AS [customerid]
    ,[Extent1].[jobid] AS [jobid]
    ,[Extent1].[lockdtdate] AS [lockdtdate]
    ,[Extent1].[lockdttime] AS [lockdttime]
    ,[Extent1].[operatorid] AS [operatorid]
    ,[Extent1].[lockstatus] AS [lockstatus]
    ,[Extent1].[changes] AS [changes]
FROM [dbo].[joblock] AS [Extent1]
WHERE ([Extent1].[customerid] = 'TESTTK')
    AND ([Extent1].[jobid] = 'AK2015818002WL')
    AND ([Extent1].[operatorid] = 'ADMIN')
    AND (N'Exclusive' = [Extent1].[lockstatus])
===================
SQL    SELECT TOP (1) [Extent1].[customerid] AS [customerid]
    ,[Extent1].[jobid] AS [jobid]
    ,[Extent1].[lockdtdate] AS [lockdtdate]
    ,[Extent1].[lockdttime] AS [lockdttime]
    ,[Extent1].[operatorid] AS [operatorid]
    ,[Extent1].[lockstatus] AS [lockstatus]
    ,[Extent1].[changes] AS [changes]
FROM [dbo].[joblock] AS [Extent1]
WHERE ([Extent1].[customerid] = 'TESTTK')
    AND ([Extent1].[jobid] = 'AK2015818002WL')
    AND ([Extent1].[operatorid] = 'ADMIN')
    AND (N'Shared' = [Extent1].[lockstatus])
===================
SQL    INSERT [dbo].[joblock] (
    [customerid]
    ,[jobid]
    ,[lockdtdate]
    ,[lockdttime]
    ,[operatorid]
    ,[lockstatus]
    ,[changes]
    )
VALUES (
    @0
    ,@1
    ,@2
    ,@3
    ,@4
    ,@5
    ,NULL
    )
===================
SQL    Closed connection at 9/22/2015 2:47:50 PM -05:00
===================
EXCEPTION    Unhandled exception caught: The underlying provider failed on Rollback.
===================
EXCEPTION    Inner Exception: Value cannot be null.
Parameter name: connection

两次选择都成功，然后插入由于某种原因失败.抛出异常，并且由于某种原因连接在 Rollback() 执行之前关闭.

The two selects are succeeding, then the insert is failing for some reason. throwing an exception, and for some reason the connection is closing before the Rollback() executes.

任何想法我做错了什么?

Any ideas what I'm doing wrong?

==== 添加堆栈跟踪 ====

==== Adding stack traces ====

外部异常的堆栈跟踪:

   at System.Data.Entity.Core.EntityClient.EntityTransaction.Rollback()
   at korterra.kt_api.Shared.TicketLockWrangler.getSharedLock(String jobid)
   at korterra.kt_ws.ApiControllers.Shared.TicketLockController.getSharedLock(TicketLockDTO ticketLockDTO)
   at lambda_method(Closure , Object , Object[] )
   at System.Web.Http.Controllers.ReflectedHttpActionDescriptor.ActionExecutor.<>c__DisplayClass10.<GetExecutor>b__9(Object instance, Object[] methodParameters)
   at System.Web.Http.Controllers.ReflectedHttpActionDescriptor.ActionExecutor.Execute(Object instance, Object[] arguments)
   at System.Web.Http.Controllers.ReflectedHttpActionDescriptor.ExecuteAsync(HttpControllerContext controllerContext, IDictionary`2 arguments, CancellationToken cancellationToken)
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Web.Http.Tracing.ITraceWriterExtensions.<TraceBeginEndAsyncCore>d__18`1.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Web.Http.Controllers.ApiControllerActionInvoker.<InvokeActionAsyncCore>d__0.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Web.Http.Tracing.ITraceWriterExtensions.<TraceBeginEndAsyncCore>d__18`1.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Web.Http.Controllers.ActionFilterResult.<ExecuteAsync>d__2.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Web.Http.Filters.AuthorizationFilterAttribute.<ExecuteAuthorizationFilterAsyncCore>d__2.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Web.Http.Controllers.ExceptionFilterResult.<ExecuteAsync>d__0.MoveNext()

内部异常的堆栈跟踪:

   at System.Data.Entity.Utilities.Check.NotNull[T](T value, String parameterName)
   at System.Data.Entity.Infrastructure.Interception.DbTransactionInterceptionContext.WithConnection(DbConnection connection)
   at System.Data.Entity.Infrastructure.Interception.DbTransactionDispatcher.Rollback(DbTransaction transaction, DbInterceptionContext interceptionContext)
   at System.Data.Entity.Core.EntityClient.EntityTransaction.Rollback()

推荐答案

经过讨论，我开始记录异常，然后尝试回滚 - 这揭示了错误.

After the discussion, I started logging the exception before trying to roll back - and that revealed the error.

事务已死锁:

Exception in getSharedLock("ticketnumber123456"): An error occurred while updating the entries. See the inner exception for details.

Inner Exception: An error occurred while updating the entries. See the inner exception for details.

Inner Exception: Transaction (Process ID 139) was deadlocked on lock resources with another process and has been chosen as the deadlock victim. Rerun the transaction.

从我所读到的，当你告诉一个事务已经成为死锁的牺牲品时，它已经被回滚了.也许这就是我们得到异常的原因?

From what I'm reading, when your told a transaction has been made a deadlock victim, it's already been rolled back. Perhaps that is why we're getting an exception?

修复似乎是识别我们何时死锁而不回滚，或者不使用事务，并在我们遇到主键违规时重试.

The fix seems to be either to recognize when we've deadlocked, and not rollback, or to not use transactions, and retry when we get a primary key violation.

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