Question

在下面的.Net Framework代码中，确保将someEntity对象插入db中，然后将执行Publish操作。但是，在.Net Core中，我无法做到这一点。当我尝试运行这段代码时，发生平台异常。

using (var transaction = new TransactionScope())
{
    SomeEntity someEntity = new SomeEntity();
    someEntity.Gui = Guid.NewGuid().ToString();

    _dataContext.SomeEntities.Add(someEntity);
    _dataContext.SaveChanges();

    _backgroundJobClient.Enqueue(() => PublishSomeEntityCreatedEvent(someEntity.Id)));

    transaction.Complete();
}

对于这种情况，是否有任何已知的好的解决方案？

注意：.Net Core 2.2控制台应用程序，EntityFrameworkCore 2.1和Hangfire 1.6.21用于测试

更新：整个堆栈跟踪

Hangfire.BackgroundJobClientException: Background job creation failed. See inner exception for details. ---> System.PlatformNotSupportedException: This platform
 does not support distributed transactions.
   at System.Transactions.Distributed.DistributedTransactionManager.GetDistributedTransactionFromTransmitterPropagationToken(Byte[] propagationToken)
   at System.Transactions.TransactionInterop.GetDistributedTransactionFromTransmitterPropagationToken(Byte[] propagationToken)
   at System.Transactions.TransactionStatePSPEOperation.PSPEPromote(InternalTransaction tx)
   at System.Transactions.TransactionStateDelegatedBase.EnterState(InternalTransaction tx)
   at System.Transactions.EnlistableStates.Promote(InternalTransaction tx)
   at System.Transactions.Transaction.Promote()
   at System.Transactions.TransactionInterop.ConvertToDistributedTransaction(Transaction transaction)
   at System.Transactions.TransactionInterop.GetExportCookie(Transaction transaction, Byte[] whereabouts)
   at System.Data.SqlClient.SqlInternalConnection.GetTransactionCookie(Transaction transaction, Byte[] whereAbouts)
   at System.Data.SqlClient.SqlInternalConnection.EnlistNonNull(Transaction tx)
   at System.Data.SqlClient.SqlInternalConnection.Enlist(Transaction tx)
   at System.Data.SqlClient.SqlInternalConnectionTds.Activate(Transaction transaction)
   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.ProviderBase.DbConnectionClosed.TryOpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions)
   at System.Data.SqlClient.SqlConnection.TryOpen(TaskCompletionSource`1 retry)
   at System.Data.SqlClient.SqlConnection.Open()
   at Hangfire.SqlServer.SqlServerStorage.CreateAndOpenConnection()
   at Hangfire.SqlServer.SqlServerStorage.UseConnection[T](DbConnection dedicatedConnection, Func`2 func)
   at Hangfire.SqlServer.SqlServerConnection.CreateExpiredJob(Job job, IDictionary`2 parameters, DateTime createdAt, TimeSpan expireIn)
   at Hangfire.Client.CoreBackgroundJobFactory.Create(CreateContext context)
   at Hangfire.Client.BackgroundJobFactory.<>c__DisplayClass7_0.<CreateWithFilters>b__0()
   at Hangfire.Client.BackgroundJobFactory.InvokeClientFilter(IClientFilter filter, CreatingContext preContext, Func`1 continuation)
   at Hangfire.Client.BackgroundJobFactory.<>c__DisplayClass7_1.<CreateWithFilters>b__2()
   at Hangfire.Client.BackgroundJobFactory.CreateWithFilters(CreateContext context, IEnumerable`1 filters)
   at Hangfire.Client.BackgroundJobFactory.Create(CreateContext context)
   at Hangfire.BackgroundJobClient.Create(Job job, IState state)
   --- End of inner exception stack trace ---
   at Hangfire.BackgroundJobClient.Create(Job job, IState state)
   at Hangfire.BackgroundJobClientExtensions.Create(IBackgroundJobClient client, Expression`1 methodCall, IState state)
   at Hangfire.BackgroundJobClientExtensions.Enqueue(IBackgroundJobClient client, Expression`1 methodCall)
   at TopShelf_Hangfire_NetCore.BusinessService.Execute(DateTime utcNow) in C:\Projects\Practices\TopShelf_Hangfire_NetCore\BusinessService.cs:line 31
   at TopShelf_Hangfire_NetCore.StartupService._timer_Elapsed(Object sender, ElapsedEventArgs e) in C:\Projects\Practices\TopShelf_Hangfire_NetCore\StartupService.cs:line 35

Answer 1

.net内核似乎不支持分布式事务的启动，而abd不受支持。

由于您要访问多个资源管理器（您的数据库和hangfire的数据库），所以transactionscope尝试升级要分配的事务。

您可以将hangfire的_backgroundJobClient.Enqueue()排除在范围之外，这样就不会升级。

您将必须找到另一种方法来确保两个操作都被执行（db更新，hangfire入队）

编辑：由于您无法进行事务处理，因此必须设计服务以处理可能的故障情况。例如：帐户服务将：

将创建的内容持久保存到数据库
然后调用hangfire Enqueue
记录以下事实：hangfire作业是在同一用户db中创建的。
用户服务必须轮询数据库，以查看是否创建了用户，但未记录通知。

其他微服务应该能够处理重复的通知。

这样，如果创建了用户但未发送通知，则您的服务将重新发送（4）。

如果失败发生在（2）和（3）之间，则接收服务将忽略重复的请求

Answer 2

在使用EntityFramework Core 3.0或更高版本时，此功能现在可以使用。这在EFCore 2.x中不起作用的原因是EFCore 2.x在不使用时未关闭连接。相反，DbConnection保持打开状态，直到上下文被处理为止。

此行为在EF Core 3.0中已更改：https://docs.microsoft.com/en-us/ef/core/what-is-new/ef-core-3.0/breaking-changes#database-connection-is-now-closed-if-not-used-anymore-before-the-transactionscope-has-been-completed

从3.0开始，EF Core在使用完连接后立即关闭连接。这样可以实现您的方案，即您希望在同一事务中加入EfCore和Hangfire，而无需升级到MSDTC。

Hangfire交易流程（工作单元）

2 个答案: