Question

I got a WCF service that has simple method called GetLineBusses.

public MobileResponse GetLineBusses(MobileRequest Request)
    {
        MobileResponse response = new MobileResponse();
        using (var entities = new NerdeBuOtobusEntities())
        {


            Line line = null;
            List<Point> points = new List<Point>();
            City city = entities.Cities.SingleOrDefault(t => t.ID == Request.CityID);
            try
            {
                line = entities.Lines.SingleOrDefault(t => t.ID == Request.LineID);
                //if (line != null)
                //{
                //    points = entities.Points.ToList().Where(t => t.LineID == Request.LineID && Request.WithPoints == true).ToList();
                //}
            }
            catch (System.Exception ex)
            {

            }
            FetcherManager fetcherManager = new FetcherManager(city);
            List<Bus> busses = fetcherManager.GetLineBusses(line);

            List<BusDTO> busDtos = new List<BusDTO>();

            foreach (Bus bus in busses)
            {
                BusDTO aBus = new BusDTO(bus);
                busDtos.Add(aBus);
            }
            response.Points = points.Select(t => new PointDTO(t)).ToList();
            response.Busses = busDtos;
        }

        return response;
    }

What I observed is that when I publish the method above, each query to method increases my IIS worker process ram use up to 160,000 kb. In order to find out the problem, I commented out

City city = entities.Cities.SingleOrDefault(t => t.ID == Request.CityID);

and

line = entities.Lines.SingleOrDefault(t => t.ID == Request.LineID);

Now that the ram use for method is minimized to 20,000. I think the problem is because of entity framework especially LINQ. By the way, I have tried static queries in order to decrease the memory use however It did not work at all. How can I solve this problem? I want to minimize the ram use by using LINQ…

Regards

Kemal

Answer 1

The below line is calling ToList() on entities.Points. This results in the entire Points table being loaded into the DataContext, and then the Where() clause is applied.

points = entities.Points.ToList().Where(t => t.LineID == Request.LineID && Request.WithPoints == true).ToList(); 

Try removing the ToList() after entities.Points. For example,

points = entities.Points.Where(t => t.LineID == Request.LineID && Request.WithPoints == true).ToList();