EntityFramework DbContext生命周期+ Postgres:“一个操作已经在进行中." [英] EntityFramework DbContext lifecycle + Postgres: "An operation is already in progress."
问题描述
几天来我一直在搞乱以下内容.
我有一个运行在Mono上的Nancy应用，带有带有存储库模式和UnitOfWork的EntityFramework，以及Postgres.南希使用TinyIoC作为IoC容器.
我有一个Web应用程序，该应用程序在前端排队请求，因此后端一次命中一个请求.一切正常.
但是，当我运行一个iOS应用程序时，麻烦就开始了，该应用程序连接到同一后端，并且不将请求排队到后端，有时几乎同时触发请求.
后端随机地开始抛出此错误:
2016-09-20T13:30:16.120057436Z app[web.1]: System.Data.Entity.Core.EntityCommandExecutionException: An error occurred while executing the command definition. See the inner exception for details. ---> System.InvalidOperationException: An operation is already in progress.
2016-09-20T13:30:16.120104535Z app[web.1]: at Npgsql.NpgsqlConnector.StartUserAction (ConnectorState newState) <0x41ad0150 + 0x00313> in <filename unknown>:0
2016-09-20T13:30:16.120113254Z app[web.1]: at Npgsql.NpgsqlCommand.ExecuteDbDataReaderInternal (CommandBehavior behavior) <0x41acfe30 + 0x0002f> in <filename unknown>:0
2016-09-20T13:30:16.120119308Z app[web.1]: at Npgsql.NpgsqlCommand.ExecuteDbDataReader (CommandBehavior behavior) <0x41acfe00 + 0x00013> in <filename unknown>:0
2016-09-20T13:30:16.120125313Z app[web.1]: at System.Data.Common.DbCommand.ExecuteReader (CommandBehavior behavior) <0x41f1a3c0 + 0x00018> in <filename unknown>:0
2016-09-20T13:30:16.120131185Z app[web.1]: at (wrapper remoting-invoke-with-check) System.Data.Common.DbCommand:ExecuteReader (System.Data.CommandBehavior)
2016-09-20T13:30:16.120206045Z app[web.1]: at System.Data.Entity.Infrastructure.Interception.DbCommandDispatcher.<Reader>b__c (System.Data.Common.DbCommand t, System.Data.Entity.Infrastructure.Interception.DbCommandInterceptionContext`1 c) <0x41f1ac20 + 0x00027> in <filename unknown>:0
2016-09-20T13:30:16.120220450Z app[web.1]: at System.Data.Entity.Infrastructure.Interception.InternalDispatcher`1[TInterceptor].Dispatch[TTarget,TInterceptionContext,TResult] (System.Data.Entity.Infrastructure.Interception.TTarget target, System.Func`3 operation, System.Data.Entity.Infrastructure.Interception.TInterceptionContext interceptionContext, System.Action`3 executing, System.Action`3 executed) <0x41b1d3c0 + 0x0010e> in <filename unknown>:0
2016-09-20T13:30:16.120232740Z app[web.1]: at System.Data.Entity.Infrastructure.Interception.DbCommandDispatcher.Reader (System.Data.Common.DbCommand command, System.Data.Entity.Infrastructure.Interception.DbCommandInterceptionContext interceptionContext) <0x41f1a880 + 0x00263> in <filename unknown>:0
2016-09-20T13:30:16.120267802Z app[web.1]: at System.Data.Entity.Internal.InterceptableDbCommand.ExecuteDbDataReader (CommandBehavior behavior) <0x41f1a3f0 + 0x000e6> in <filename unknown>:0
2016-09-20T13:30:16.120274613Z app[web.1]: at System.Data.Common.DbCommand.ExecuteReader (CommandBehavior behavior) <0x41f1a3c0 + 0x00018> in <filename unknown>:0
2016-09-20T13:30:16.120318116Z app[web.1]: at (wrapper remoting-invoke-with-check) System.Data.Common.DbCommand:ExecuteReader (System.Data.CommandBehavior)
2016-09-20T13:30:16.120326788Z app[web.1]: at System.Data.Entity.Core.EntityClient.Internal.EntityCommandDefinition.ExecuteStoreCommands (System.Data.Entity.Core.EntityClient.EntityCommand entityCommand, CommandBehavior behavior) <0x41f154c0 + 0x00043> in <filename unknown>:0
2016-09-20T13:30:16.120332587Z app[web.1]: --- End of inner exception stack trace ---
2016-09-20T13:30:16.120336995Z app[web.1]: at System.Data.Entity.Core.EntityClient.Internal.EntityCommandDefinition.ExecuteStoreCommands (System.Data.Entity.Core.EntityClient.EntityCommand entityCommand, CommandBehavior behavior) <0x41f154c0 + 0x000b3> in <filename unknown>:0
2016-09-20T13:30:16.120344218Z app[web.1]: at System.Data.Entity.Core.Objects.Internal.ObjectQueryExecutionPlan.Execute[TResultType] (System.Data.Entity.Core.Objects.ObjectContext context, System.Data.Entity.Core.Objects.ObjectParameterCollection parameterValues) <0x41f11e50 + 0x000a4> in <filename unknown>:0
我正在Nancy bootstrapper中注册类似的依赖项:
protected override void ConfigureApplicationContainer (TinyIoCContainer container)
{
base.ConfigureApplicationContainer (container);
Database.SetInitializer<ReflectDbContext> (new NullDatabaseInitializer<ReflectDbContext> ()); // add this to allow prevent "The context cannot be used while the model is being created"
container.Register<IReflectDbContext, ReflectDbContext> ();
container.Register<ReflectUnitOfWork> ().AsSingleton ();
container.Register<IReflectUserRepository, ReflectUserRepository> ();
container.Register<IUserRepository<ReflectUser>, ReflectUserRepository> ();
container.Register<IReviewRepository, ReviewRepository> ();
container.Register<IReviewSetupRepository, ReviewSetupRepository> ();
container.Register<IRepositoryV2<ReflectUserActivityItem>, EntityFrameworkRepository<ReflectUserActivityItem>> ();
container.Register<IAuthenticationUnitOfWork<ReflectUser, ReflectUserActivityItem>, ReflectUnitOfWork> ();
container.Register<IRepository<ReflectUserActivityItem>, NullRepository<ReflectUserActivityItem>> (); //TODO remove this when port is complete
container.Register<IErrorLogger, SimpleLogLogger> ();
container.Register<IGeoIpDataProvider, TelizeGeoIpDataProvider> ();
container.Register<IRepository<ReviewSetup>, ServiceStackOrmLiteRepository<ReviewSetup>> ();
container.Register<IEmailExporter, MailChimpUserEmailDataExporter> ();
container.Register<IMailer, SmtpMailer> ();
container.Register<IUserManager<ReflectUser>, UserManager<ReflectUser, ReflectUserActivityItem>> ();
container.Register<IUserMessageManager<ReflectUser>, UserMessageManager<ReflectUser>> ();
etc...
}
我感觉这是一个多线程问题，并且两个单独的请求正在使用相同的DbContext(或基础连接)，这会导致事情崩溃.
我已经尝试在Nancy bootstrapper的ConfigureRequestContainer方法中注册依赖项，但这会引发连接未打开"异常.
此问题背后的理论在本文中得到了清晰的解释: http://mehdi.me /ambient-dbcontext-in-ef6/
我不清楚以下内容:
- 我是否可以假设这是一个多线程问题?
- 我需要知道确保每个请求使用其自己的DbContext/连接的正确方法，以便不会发生冲突，最好使用TinyIoC/Nancy管理DbContext的生命周期.
我知道这是一个复杂的问题.让我知道您是否需要其他信息.
谢谢:-).
将稍微扩展我的评论，以供将来可能有相同错误的人参考.您可能已经知道，Entity Framework的DbContext遵循所谓的工作单元"模式，这意味着您必须为一个逻辑工作单元(一个单元)使用一个实例.不需要为多个工作单元重用同一实例，并且在某些情况下甚至可能导致失败.与SQL Server不同，Postgresql不支持MARS(多个活动结果集)，这意味着它不支持通过同一连接同时执行多个命令.当您从多个线程重用DbContext的单个实例时，它们在执行命令时会重用同一基础SQL连接，这将导致上述错误.
如评论中所述，解决此问题的方法始终是为每个操作创建DbContext的新实例，然后将其处置.这意味着将其注册为
container.Register<IReflectDbContext, ReflectDbContext> ().AsMultiInstance();
，并确保您永远不要将DbConext实例存储在另一个类的静态字段\单例实例中(例如，您的ReflectUnitOfWork是单例，并且如果您将DbContext存储在该字段中-再次出现相同的问题).
I have been messing with the following for a few days now.
I have a Nancy app running on Mono, with EntityFramework with Repository pattern and UnitOfWork, and Postgres. Nancy uses TinyIoC as it's IoC container.
I have a web app that queues requests on the front-end so the back-end gets hit one request at a time. This all works fine.
However, the trouble starts when I run an iOS app that connects to the same back-end and does not queue requests to the backend, firing request sometimes almost simultaneously.
At random intervals the backend starts throwing this error:
2016-09-20T13:30:16.120057436Z app[web.1]: System.Data.Entity.Core.EntityCommandExecutionException: An error occurred while executing the command definition. See the inner exception for details. ---> System.InvalidOperationException: An operation is already in progress.
2016-09-20T13:30:16.120104535Z app[web.1]: at Npgsql.NpgsqlConnector.StartUserAction (ConnectorState newState) <0x41ad0150 + 0x00313> in <filename unknown>:0
2016-09-20T13:30:16.120113254Z app[web.1]: at Npgsql.NpgsqlCommand.ExecuteDbDataReaderInternal (CommandBehavior behavior) <0x41acfe30 + 0x0002f> in <filename unknown>:0
2016-09-20T13:30:16.120119308Z app[web.1]: at Npgsql.NpgsqlCommand.ExecuteDbDataReader (CommandBehavior behavior) <0x41acfe00 + 0x00013> in <filename unknown>:0
2016-09-20T13:30:16.120125313Z app[web.1]: at System.Data.Common.DbCommand.ExecuteReader (CommandBehavior behavior) <0x41f1a3c0 + 0x00018> in <filename unknown>:0
2016-09-20T13:30:16.120131185Z app[web.1]: at (wrapper remoting-invoke-with-check) System.Data.Common.DbCommand:ExecuteReader (System.Data.CommandBehavior)
2016-09-20T13:30:16.120206045Z app[web.1]: at System.Data.Entity.Infrastructure.Interception.DbCommandDispatcher.<Reader>b__c (System.Data.Common.DbCommand t, System.Data.Entity.Infrastructure.Interception.DbCommandInterceptionContext`1 c) <0x41f1ac20 + 0x00027> in <filename unknown>:0
2016-09-20T13:30:16.120220450Z app[web.1]: at System.Data.Entity.Infrastructure.Interception.InternalDispatcher`1[TInterceptor].Dispatch[TTarget,TInterceptionContext,TResult] (System.Data.Entity.Infrastructure.Interception.TTarget target, System.Func`3 operation, System.Data.Entity.Infrastructure.Interception.TInterceptionContext interceptionContext, System.Action`3 executing, System.Action`3 executed) <0x41b1d3c0 + 0x0010e> in <filename unknown>:0
2016-09-20T13:30:16.120232740Z app[web.1]: at System.Data.Entity.Infrastructure.Interception.DbCommandDispatcher.Reader (System.Data.Common.DbCommand command, System.Data.Entity.Infrastructure.Interception.DbCommandInterceptionContext interceptionContext) <0x41f1a880 + 0x00263> in <filename unknown>:0
2016-09-20T13:30:16.120267802Z app[web.1]: at System.Data.Entity.Internal.InterceptableDbCommand.ExecuteDbDataReader (CommandBehavior behavior) <0x41f1a3f0 + 0x000e6> in <filename unknown>:0
2016-09-20T13:30:16.120274613Z app[web.1]: at System.Data.Common.DbCommand.ExecuteReader (CommandBehavior behavior) <0x41f1a3c0 + 0x00018> in <filename unknown>:0
2016-09-20T13:30:16.120318116Z app[web.1]: at (wrapper remoting-invoke-with-check) System.Data.Common.DbCommand:ExecuteReader (System.Data.CommandBehavior)
2016-09-20T13:30:16.120326788Z app[web.1]: at System.Data.Entity.Core.EntityClient.Internal.EntityCommandDefinition.ExecuteStoreCommands (System.Data.Entity.Core.EntityClient.EntityCommand entityCommand, CommandBehavior behavior) <0x41f154c0 + 0x00043> in <filename unknown>:0
2016-09-20T13:30:16.120332587Z app[web.1]: --- End of inner exception stack trace ---
2016-09-20T13:30:16.120336995Z app[web.1]: at System.Data.Entity.Core.EntityClient.Internal.EntityCommandDefinition.ExecuteStoreCommands (System.Data.Entity.Core.EntityClient.EntityCommand entityCommand, CommandBehavior behavior) <0x41f154c0 + 0x000b3> in <filename unknown>:0
2016-09-20T13:30:16.120344218Z app[web.1]: at System.Data.Entity.Core.Objects.Internal.ObjectQueryExecutionPlan.Execute[TResultType] (System.Data.Entity.Core.Objects.ObjectContext context, System.Data.Entity.Core.Objects.ObjectParameterCollection parameterValues) <0x41f11e50 + 0x000a4> in <filename unknown>:0
I am registering the dependencies like to, in the Nancy bootstrapper:
protected override void ConfigureApplicationContainer (TinyIoCContainer container)
{
base.ConfigureApplicationContainer (container);
Database.SetInitializer<ReflectDbContext> (new NullDatabaseInitializer<ReflectDbContext> ()); // add this to allow prevent "The context cannot be used while the model is being created"
container.Register<IReflectDbContext, ReflectDbContext> ();
container.Register<ReflectUnitOfWork> ().AsSingleton ();
container.Register<IReflectUserRepository, ReflectUserRepository> ();
container.Register<IUserRepository<ReflectUser>, ReflectUserRepository> ();
container.Register<IReviewRepository, ReviewRepository> ();
container.Register<IReviewSetupRepository, ReviewSetupRepository> ();
container.Register<IRepositoryV2<ReflectUserActivityItem>, EntityFrameworkRepository<ReflectUserActivityItem>> ();
container.Register<IAuthenticationUnitOfWork<ReflectUser, ReflectUserActivityItem>, ReflectUnitOfWork> ();
container.Register<IRepository<ReflectUserActivityItem>, NullRepository<ReflectUserActivityItem>> (); //TODO remove this when port is complete
container.Register<IErrorLogger, SimpleLogLogger> ();
container.Register<IGeoIpDataProvider, TelizeGeoIpDataProvider> ();
container.Register<IRepository<ReviewSetup>, ServiceStackOrmLiteRepository<ReviewSetup>> ();
container.Register<IEmailExporter, MailChimpUserEmailDataExporter> ();
container.Register<IMailer, SmtpMailer> ();
container.Register<IUserManager<ReflectUser>, UserManager<ReflectUser, ReflectUserActivityItem>> ();
container.Register<IUserMessageManager<ReflectUser>, UserMessageManager<ReflectUser>> ();
etc...
}
I have a feeling that this is a multi-threading issue and that two separate requests are using the same DbContext (or underlying connection) which causes things to blow up.
I have already tried registering the dependencies in the ConfigureRequestContainer method of the Nancy bootstrapper but this throw a 'Connection is not open` exception.
The theory behind this issue is explained clearly in this article: http://mehdi.me/ambient-dbcontext-in-ef6/
The following is unclear to me:
- Am I correct in assuming this is a multi-threading issue?
- I need to know the proper way to make sure each request uses it's own DbContext/connection so stuff doesn't collide, perferably using TinyIoC/Nancy to manage the lifecycle of the DbContext.
I understand this is a complex issue. Let me know if you need any additional information.
Thank you :-).
Will a bit expand my comments for future reference of people who might have the same error. As you probably know already, Entity Framework's DbContext follows so called "unit of work" pattern, which means you have to use one instance for one logical piece (unit) of work. Reusing the same instance for multiple units of work is not desired, and in some cases like this may even lead to failures. Unlike SQL Server, Postgresql does not support MARS (Multiple Active Result Sets), which means it does not support executing multiple commands over the same connection at the same time. When you reuse single instance of DbContext from multiple threads, they reusing the same underlying sql connection when executing their commands, which leads to the error above.
As stated in comments, the way to resolve the issue is always create new instance of DbContext for every operation, and dispose it afterwards. This means registering it as
container.Register<IReflectDbContext, ReflectDbContext> ().AsMultiInstance();
And ensure that you never store DbConext instance in a static field \ singleton instance of another class (for example your ReflectUnitOfWork is singleton, and if you store DbContext in a field there - same problem again).
这篇关于EntityFramework DbContext生命周期+ Postgres:“一个操作已经在进行中."的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
