c# - '无法访问已处置的对象。此错误的一个常见原因是处理从依赖注入(inject)中解析的上下文

Question

我将 ThreadPool 与通用存储库一起使用，但出现此错误；

'Cannot access a disposed object. A common cause of this error is disposing a context that was resolved from dependency injection and then later trying to use the same context instance elsewhere in your application. This may occur if you are calling Dispose() on the context, or wrapping the context in a using statement. If you are using dependency injection, you should let the dependency injection container take care of disposing context instances.'

private readonly AuthorizedServiceService _authorizedServiceService;
        private readonly CustomerService _customerService;
        public IConfigurationRoot Configuration { get; }

        public UpdateService(AuthorizedServiceService authorizedServiceService, CustomerService customerService)
        {
            _authorizedServiceService = authorizedServiceService;
            _customerService = customerService;
        }


        public void UpdateAllRecords()
        {

            _authorizedServiceService.GetByActive().ToList().ForEach(UpdateAuthorizedServiceRecords);
        }

        void UpdateAuthorizedServiceRecords(AuthorizedService authorizedService)
        {
            //UpdateStart(authorizedService);
            var mywatch = new Stopwatch();

            mywatch.Start();

            ThreadPool.QueueUserWorkItem(new WaitCallback(state => { UpdateStart(authorizedService); }));

            mywatch.Stop();
            mywatch.Reset();
        }


        public void UpdateStart(AuthorizedService authorizedService)
        {
            UpdateCustomers(authorizedService);
            ThreadPool.QueueUserWorkItem(new WaitCallback(state => { UpdateCustomers(authorizedService); }));

        }

        internal void UpdateCustomers(AuthorizedService authorizedService)
        {
            try
            {
                if (authorizedService.CustomerUpdateLocked)
                    return;

                var carDatabaseClient = new DataCarDatabaseClient();
                var result = carDatabaseClient.GetCustomers(authorizedService, authorizedService.LastCustomerUpdate);

                var dataRows = Convert<Customer>(result).Select(s=>
                {
                    s.Id = authorizedService.Code + "-" + s.DcId;
                    s.AuthorizedService = authorizedService;
                    return s;
                }).ToList();

                _customerService.SaveOrUpdate(dataRows.OrderBy(p=>p.Id).FirstOrDefault(),p=> p.Id != null);

            }
            catch (Exception e)
            {
                // ignored
            }
        }

通用存储库方法；

public void AddOrUpdate(T entity, Expression<Func<T, bool>> predicate)
{
    var exists = predicate != null ? Context.Set<T>().Any(predicate) : Context.Set<T>().Any();
    if (!exists)
        Context.Set<T>().Add(entity);
    else
        Context.Set<T>().Update(entity);

    Context.SaveChanges();
}

Answer 1

发生这种情况是因为主线程中的所有依赖项在其执行完成时被释放，而您正试图在另一个线程中访问它们。要处理这种情况，您需要在后台线程中创建一个作用域并在那里解析 AuthorizedServiceService:

private readonly IServiceScopeFactory _scopeFactory;

public UpdateService(AuthorizedServiceService authorizedServiceService, CustomerService customerService, IServiceScopeFactory scopeFactory)
{
    _authorizedServiceService = authorizedServiceService;
    _customerService = customerService;
    _scopeFactory = scopeFactory;
}

public void UpdateStart(AuthorizedService authorizedService)
{    
    ThreadPool.QueueUserWorkItem(new WaitCallback(state => { 
    using (scope = _scopeFactory.CreateScope())
    {
        var scopedAuthorizedService = scope.ServiceProvider.GetService(typeof(AuthorizedServiceService));
        UpdateCustomers(scopedAuthorizedService); }));
    }
 }