Entity framework uses a lot of memory

Question

Here is a image from the ANTS memory profiler. It seens that there are a lot of objects hold in memory. How can I find what I am doing wrong?

**UPDATE**

Here is my repository classes:

public class Repository<T> : IRepository<T> where T : class, IDataEntity
    {
        ObjectContext _context;
        IObjectSet<T> _objectSet;

        readonly string _entitySetName;
        readonly string[] _keyNames;

        private ObjectContext Context
        {
            get
            {
                if (_context == null)
                {
                    _context = GetCurrentUnitOfWork<EFUnitOfWork>().Context;
                }
                return _context;
            }
        }

        private IObjectSet<T> ObjectSet
        {
            get
            {
                if (_objectSet == null)
                {
                    _objectSet = this.Context.CreateObjectSet<T>();
                }
                return _objectSet;
            }
        }

        public TUnitOfWork GetCurrentUnitOfWork<TUnitOfWork>() where TUnitOfWork : IUnitOfWork
        {
            return (TUnitOfWork)UnitOfWork.Current;
        }

        public virtual IEnumerable<T> GetQuery()
        {
            return ObjectSet;
        }

        public virtual IEnumerable<T> GetQuery(params Expression<Func<T, object>>[] includes)
        {
            return ObjectSet.IncludeMultiple(includes);
        }

        public virtual IEnumerable<T> GetQuery(
            IEnumerable<Expression<Func<T, bool>>> filters,
            Func<IQueryable<T>, IOrderedQueryable<T>> orderBy,
            IEnumerable<Expression<Func<T, object>>> includes)
        {
            IQueryable<T> _query = ObjectSet;

            if (filters != null)
            {
                foreach (var filter in filters)
                {
                    _query = _query.Where(filter);
                }
            }

            if (includes != null && includes.Count() > 0)
            {
                _query = _query.IncludeMultiple(includes.ToArray());
            }

            if (orderBy != null)
            {
                _query = orderBy(_query);
            }

            return _query;
        }

        public virtual IPaged<T> GetQuery(
            IEnumerable<Expression<Func<T, bool>>> filters,
            Func<IQueryable<T>, IOrderedQueryable<T>> orderBy,
            int pageNumber, int pageSize,
            IEnumerable<Expression<Func<T, object>>> includes)
        {
            IQueryable<T> _query = ObjectSet;

            if (filters != null)
            {
                foreach (var filter in filters)
                {
                    _query = _query.Where(filter);
                }
            }

            if (orderBy != null)
            {
                _query = orderBy(_query);
            }

            IPaged<T> page = new Paged<T>(_query, pageNumber, pageSize, includes);

            return page;
        }

        public virtual void Insert(T entity)
        {
            this.ObjectSet.AddObject(entity);
        }

        public virtual void Delete(T entity)
        {
            if (entity is ISoftDeletable)
            {
                ((ISoftDeletable)entity).IsDeleted = true;
                //Update(entity);
            }
            else
            {
                this.ObjectSet.DeleteObject(entity);
            }
        }

        public virtual void Attach(T entity)
        {
            ObjectStateEntry entry = null;
            if (this.Context.ObjectStateManager.TryGetObjectStateEntry(entity, out entry) == false)
            {
                this.ObjectSet.Attach(entity);
            }
        }

        public virtual void Detach(T entity)
        {
            ObjectStateEntry entry = null;
            if (this.Context.ObjectStateManager.TryGetObjectStateEntry(entity, out entry) == true)
            {
                this.ObjectSet.Detach(entity);
            }
        }
    }

Now, if I have class A that holds records from table A, I also create class:

public class ARepository:BaseRepository<A> {
// Implementation of A's queries and specific db operations
}

Here is my EFUnitOfWork class:

public class EFUnitOfWork : IUnitOfWork, IDisposable
{
    public ObjectContext Context { get; private set; }

    public EFUnitOfWork(ObjectContext context)
    {
        Context = context;
        context.ContextOptions.LazyLoadingEnabled = true;
    }

    public void Commit()
    {
        Context.SaveChanges();
    }

    public void Dispose()
    {
        if (Context != null)
        {
            Context.Dispose();
        }
        GC.SuppressFinalize(this);
    }
}

And UnitOfWork class:

public static class UnitOfWork
{
    private const string HTTPCONTEXTKEY = "MyProj.Domain.Business.Repository.HttpContext.Key";

    private static IUnitOfWorkFactory _unitOfWorkFactory;
    private static readonly Hashtable _threads = new Hashtable();

    public static void Commit()
    {
        IUnitOfWork unitOfWork = GetUnitOfWork();
        if (unitOfWork != null)
        {
            unitOfWork.Commit();
        }
    }

    public static IUnitOfWork Current 
    {
        get
        {
            IUnitOfWork unitOfWork = GetUnitOfWork();
            if (unitOfWork == null)
            {
                _unitOfWorkFactory = ObjectFactory.GetInstance<IUnitOfWorkFactory>();
                unitOfWork = _unitOfWorkFactory.Create();
                SaveUnitOfWork(unitOfWork);
            }
            return unitOfWork;
        }
    }

    private static IUnitOfWork GetUnitOfWork()
    {
        if (HttpContext.Current != null)
        {
            if (HttpContext.Current.Items.Contains(HTTPCONTEXTKEY))
            {
                return (IUnitOfWork)HttpContext.Current.Items[HTTPCONTEXTKEY];
            }
            return null;
        }
        else
        {
            Thread thread = Thread.CurrentThread;
            if (string.IsNullOrEmpty(thread.Name))
            {
                thread.Name = Guid.NewGuid().ToString();
                return null;
            }
            else
            {
                lock (_threads.SyncRoot)
                {
                    return (IUnitOfWork)_threads[Thread.CurrentThread.Name];
                }
            }
        }
    }

    private static void SaveUnitOfWork(IUnitOfWork unitOfWork)
    {
        if (HttpContext.Current != null)
        {
            HttpContext.Current.Items[HTTPCONTEXTKEY] = unitOfWork;
        }
        else
        {
            lock(_threads.SyncRoot)
            {
                _threads[Thread.CurrentThread.Name] = unitOfWork;
            }
        }
    }
}

Here is how I use this:

 public class TaskPriceRepository : BaseRepository<TaskPrice>
    {
        public void Set(TaskPrice entity)
        {
            TaskPrice taskPrice = GetQuery().SingleOrDefault(x => x.TaskId == entity.TaskId);
            if (taskPrice != null)
            {
                CommonUtils.CopyObject<TaskPrice>(entity, ref taskPrice);
            }
            else
            {
                this.Insert(entity);
            }
        }
    }

public class BranchRepository : BaseRepository<Branch>
{
    public IList<Branch> GetBranchesList(Guid companyId, long? branchId, string branchName)
    {
        return Repository.GetQuery().
            Where(b => companyId == b.CompanyId).
            Where(b => b.IsDeleted == false).
            Where(b => !branchId.HasValue || b.BranchId.Equals(branchId.Value)).
            Where(b => branchName == null || b.BranchName.Contains(branchName)).
            ToList();
    }
}

[WebMethod]
public void SetTaskPrice(TaskPriceDTO taskPrice)
{
    TaskPrice tp = taskPrice.ToEntity();
    TaskPriceRepository rep = new TaskPriceRepository();
    rep.Set(tp);
    UnitOfWork.Commit();
}

[WebMethod]
public IList<Branch> GetBranchesList()
{
    BranchRepository rep = new BranchRepository();
    return rep.GetBranchesList(m_User.UserCompany.CompanyId, null, null).ToList();
}

I hope this is enough info to help me solving the problem. Thanks.

UPDATE 2
There is also UnitOfWorkFactory that initializes UnitOfWork:

public class UnitOfWorkFactory : IUnitOfWorkFactory
{
    private static Func<ObjectContext> _objectContextDelegate;
    private static readonly Object _lockObject = new object();

    public static void SetObjectContext(Func<ObjectContext> objectContextDelegate)
    {
        _objectContextDelegate = objectContextDelegate;
    }

    public IUnitOfWork Create()
    {
        ObjectContext context;
        lock (_lockObject)
        {
             context = _objectContextDelegate();
        }
        return new EFUnitOfWork(context);
    }
}

In order to use this, in the application startup I use structuremap:

  ObjectFactory.Initialize(x =>
        {
            x.For<IUnitOfWorkFactory>().Use<UnitOfWorkFactory>();
            x.For(typeof(IRepository<>)).Use(typeof(Repository<>));
        });

Answer 1

I have a hunch you don't dispose the context.
I suggest disposing the context whenever you done interacting with database.

Use using statement whenever you create the context.

[Edit]

As far as I can see, you cache and don't dispose your EFUnitOfWork object. It is disposable, which is correct, but I don't see when disposable is called. Seems like you hold a reference to the context for all application run time.
Moreover, you create and hold one context per thread, which will make it even worse.

I can't tell you for sure where you should put Dispose or using, as I don't know the usages.
You could put it probably to your Commit method, but I don't know if the Commit called only once during database interaction session.

Also, your design might be overcomplicated.

If I were you, I would:

• Find the way to dispose the context using current code, as a short-term solution
• Simplify the design, as the long-term solution

If I had time I would do long-term solution right away.
But again, I can't tell if the complexity of your design is justified, as I don't know how big your application is and what it does and what the requirements are.

Answer 2

Couple of things come to my mind:

• You aren't probably Disposing the ObjectContext. Make sure all your database codes are within using(var context = CreateObjectContext()) block
• You have an N-tier architecture and you are passing entities from the data access layer to upper layer without Detaching the entities from ObjectContext. You need to call ObjectContext.Detach(...)
• You are most likely returning a full collection of entities, instead of returning a single enity for single Get operations. For ex, you have queries like from customer in context.Customers select customer instead of doing from customer in context.Customers select customer.FirstOrDefault()

I have had hard time making Entity Framework to work in an N-tier application. It's just not suitable for using in N-tier apps as is. Only EF 4.0 is. You can read about all my adventure in making EF 3 work in an N-tier app.

http://www.codeproject.com/KB/linq/ef.aspx

Does this answer your question?