asp.net-core-mvc - 与 ToList() 相比，ToListAsync() 非常慢

Question

我有一个带有分组和多个包含的复杂 LINQ 查询。我发现 ToListAsync() 需要超过一秒才能完成，而 ToList() 只需几分之一秒即可返回。

allReservationsList = allReservations.ToList(); // fast
allReservationsList = await allReservations.ToListAsync(); // more then a second for 60 rows

我做错了什么还是 Entity Framework 有问题？

这是查询:

            var reservations = db.Reservations
                .Include(r => r.PickUpLocation)
                .Include(r => r.ReturnLocation)
                .Include(r => r.RequestedVehicleModel).ThenInclude(m => m.Photos)
                .Include(r => r.RequestedVehicleModel.VehicleType.VehicleModels)
                .Include(r => r.RequestedVehicleType).ThenInclude(t => t.Photos)
                .Include(r => r.AssignedUnit.VehicleModel.VehicleType)
                .Include(r => r.DailyPrice.Currency);

            var allReservations =
                from r in reservations
                orderby r.VersionDate descending
                group r by r.BookingCode into g
                select g;

Answer 1

这里的变量太多了。但是，一般来说，异步方法的返回时间会比同步方法更长，因为异步方法的开销更大。无论这是否是您所看到的整个延迟的原因，至少根据您提供的信息，都无法判断。