Microsoft.EntityFrameworkCore异常System.InvalidOperationException

悬赏园豆：200 [已解决问题] 解决于 2018-08-17 12:58

场景描述：

单位项目目前使用Masstransit rabbitmq 做发布订阅

订阅方接收到消息后会做一些增删改动作

数据操作用的EntityFramworkCore，DbContext使用Autofac注入的，范围是InstancePerLifetimeScope

问题：

目前发现如果出现并发的情况，数据增删改会出现异常

System.InvalidOperationException

A second operation started on this context before a previous operation completed. Any instance members are not guaranteed to be thread safe.

代码：

发布方

 public CommonOutputDto SystemLoginOut(SystemLoginOutRequest systemLoginOutRequest)
        {
            var result = new CommonOutputDto() { IsSuccess = true };
            foreach (var distributorID in systemLoginOutRequest.Distributors)
            {
                var model = _ssoAuthTokenRepository.Table.Where(x => x.DISTRIBUTOR_ID.Equals(distributorID));
                if (model.Count() > 0)
                {
                    _ssoAuthTokenRepository.Delete(model);
                }
                //向mq发送信息
                _busControl.Publish(new SSOAuthTokenConsumer()
                {
                    DistributorID = distributorID,
                    tokenConsumerType = ToKenConsumerType.DeleteAll
                });
            }
            return result;
        }

订阅方

 public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory, IApplicationLifetime applicationLifetime)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }
            var appSettings = Configuration.Get<AppSettings>();
            if (appSettings.tokenConfig.AuthCenterType == AuthCenterType.Slave)
            {
　　　　　　　　//订阅
                var _busControl = BusConfiguration.CreateBus(appSettings,
                    (cfg, host) => cfg.ReceiveEndpoint(host, appSettings.rabbitMQConfig.QueueName, e =>
                {
                    e.Consumer<ToKenConsumer>();
                }));
                applicationLifetime.ApplicationStarted.Register(_busControl.Start);
                applicationLifetime.ApplicationStopped.Register(_busControl.Stop);
            }
            app.SwaggerConfigBuilder();
            app.UseMiddleware(typeof(ApiErrorHandlingMiddleware));
            app.UseMvc();
            app.SwaggerConfigBuilder();
        }

TokenConsumer实现注：lock是我的临时解决办法但我还是想找到问题所在

 public class ToKenConsumer : IConsumer<SSOAuthTokenConsumer>
    {
        private static readonly object ConsumerLock = new object();
        public Task Consume(ConsumeContext<SSOAuthTokenConsumer> context)
        {
            lock (ConsumerLock)
            {
                try
                {
                    var ssoService = EngineContext.Current.Resolve<ISSOService>();
                    ssoService.ResetSlaveToken(context.Message);
                }
                catch (Exception ex)
                {
                    LogHelper.Error(context.Message.tokenConsumerType.ToString() + "  " + ex.Message, ex);
                }
                return Task.CompletedTask;
            }
        }
    }

注入的DBContext

builder.RegisterType<OracleContext>().As<IDbContext>().InstancePerLifetimeScope();

ssoService的实现

        private readonly IRepository<SSOAuthToken> _ssoAuthTokenRepository;
        private readonly IDbContext _dbContext;
     
   public SSOService(
             IDbContext dbContext,
            IRepository<SSOAuthToken> ssoAuthTokenRepository)
        {
            this._dbContext = dbContext;
            this._ssoAuthTokenRepository = ssoAuthTokenRepository;
        }

public void ResetSlaveToken(SSOAuthTokenConsumer ssoAuthTokenConsumer)
        {
            switch (ssoAuthTokenConsumer.tokenConsumerType)
            {
                case ToKenConsumerType.Add:
                    {
                        var model = new SSOAuthToken()
                        {
                            ID = GetSeqID(),
                            CREATE_DATE = ssoAuthTokenConsumer.ssoAuthToken.CREATE_DATE,
                            DISTRIBUTOR_ID = ssoAuthTokenConsumer.ssoAuthToken.DISTRIBUTOR_ID,
                            TOKEN = ssoAuthTokenConsumer.ssoAuthToken.TOKEN,
                            TOKEN_TYPE = ssoAuthTokenConsumer.ssoAuthToken.TOKEN_TYPE
                        };
                        _ssoAuthTokenRepository.Insert(model);
                        break;
                    }
                case ToKenConsumerType.Update:
                    {
                        var token = ssoAuthTokenConsumer.ssoAuthToken.TOKEN;
                        var did = ssoAuthTokenConsumer.ssoAuthToken.DISTRIBUTOR_ID;
                        var model = _ssoAuthTokenRepository.Table.Where(x => x.TOKEN.Equals(token) &&
                        x.DISTRIBUTOR_ID.Equals(did)).FirstOrDefault();
                        if (model != null)
                        {
                            model.TOKEN = ssoAuthTokenConsumer.ssoAuthToken.TOKEN;
                            model.DISTRIBUTOR_ID = ssoAuthTokenConsumer.ssoAuthToken.DISTRIBUTOR_ID;
                            model.CREATE_DATE = ssoAuthTokenConsumer.ssoAuthToken.CREATE_DATE;
                            model.TOKEN_TYPE = ssoAuthTokenConsumer.ssoAuthToken.TOKEN_TYPE;
                            _ssoAuthTokenRepository.Update(model);
                        }
                        break;
                    }
                case ToKenConsumerType.Delete:
                    {
                        var token = ssoAuthTokenConsumer.ssoAuthToken.TOKEN;
                        var did = ssoAuthTokenConsumer.ssoAuthToken.DISTRIBUTOR_ID;
                        var model = _ssoAuthTokenRepository.Table.Where(x => x.TOKEN.Equals(token) &&
                        x.DISTRIBUTOR_ID.Equals(did)).FirstOrDefault();
                        if (model != null)
                        {
                            _ssoAuthTokenRepository.Delete(model);
                        }
                        break;
                    }
                case ToKenConsumerType.DeleteAll:
                    {
                        var did = ssoAuthTokenConsumer.DistributorID;
                        var model = _ssoAuthTokenRepository.Table.Where(x => x.DISTRIBUTOR_ID.Equals(did)).ToList();
                        if (model.Count() > 0)
                        {
                            _ssoAuthTokenRepository.Delete(model);
                        }
                        break;
                    }
            }
            ResetRedisToken(ssoAuthTokenConsumer.DistributorID);
        }

请各路大神帮我看看为什么会报这个错误我百度了很久但都是介绍"context before a previous asynchronous operation" 这个错误，可是我并没有用异步。

拜托各位了新注册的号还没有豆豆 - -！

232111 | 初学一级 | 园豆：22
提问于：2018-08-15 23:00

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最佳答案

ssoService 是不是被注册为单例了？

收获园豆：200

dudu | 高人七级 |园豆：30994 | 2018-08-16 08:20

园主你感觉是这句的问题 "var ssoService = EngineContext.Current.Resolve<ISSOService>();" ?

232111 | 园豆：22 (初学一级) | 2018-08-16 08:22

@232111: 代码中如何注册 ISSOService 的？

dudu | 园豆：30994 (高人七级) | 2018-08-16 08:26

@232111: 建议提供一下依赖注入部分的代码

dudu | 园豆：30994 (高人七级) | 2018-08-16 08:28

@dudu:

注入类里是这么写的

 builder.RegisterType<SSOService>().As<ISSOService>().InstancePerLifetimeScope();

但是我在TokenConsumer里并不是通过构造函数使用，而是new出来的，因为Consumer构造函数不允许有参数

var ssoService = EngineContext.Current.Resolve<ISSOService>();

232111 | 园豆：22 (初学一级) | 2018-08-16 08:30

@232111: IRepository<SSOAuthToken> 是如何注册的？

dudu | 园豆：30994 (高人七级) | 2018-08-16 08:38

@dudu:

builder.RegisterGeneric(typeof(EfRepository<>)).As(typeof(IRepository<>)).InstancePerLifetimeScope();

232111 | 园豆：22 (初学一级) | 2018-08-16 08:39

@232111: 出现这个问题是由于通一个 DbContext 实例被多个线程使用，建议把 InstancePerLifetimeScope 都改为 InstancePerHttpRequest 试试

dudu | 园豆：30994 (高人七级) | 2018-08-16 08:47

@dudu: 嗯谢谢园主我试试再问个问题我第一次使用autofac 一直以为InstancePerLifetimeScope的作用域就是当前请求的上下文不对吗？

232111 | 园豆：22 (初学一级) | 2018-08-16 08:49

@232111: 我对 autofac 也不熟悉，我们都用的是 .net core 内置的依赖注入，InstancePerHttpRequest 与 InstancePerLifetimeScope 的区别详见 Autofac - InstancePerHttpRequest vs InstancePerLifetimeScope

dudu | 园豆：30994 (高人七级) | 2018-08-16 08:51

@dudu:

园主，我的问题按你这篇文章解决的

https://www.cnblogs.com/dudu/p/9353369.html

谢谢

232111 | 园豆：22 (初学一级) | 2018-08-17 12:58

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Microsoft.EntityFrameworkCore异常System.InvalidOperationException

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