Question

I have a static DataLibrary class that implements a singleton pattern.

        public static FacilityRepository FacilRepo
        {
            get
            {
                if (_facilRepo == null)
                {
                    _facilRepo = new FacilityRepository(Authenticated.UserId);
                    if (Authenticated.FacKey.Length > 0)
                    {
                        foreach (var fac in _facilRepo)
                            fac.IsSelected = (fac.FacilityKey == Authenticated.FacKey);                        
                    }
                }
                return _facilRepo;
            }
        }

private static FacilityRepository _facilRepo;

When I access this from different threads using Task.Factory.StartNew the FacilityReposity gets recreated multiple times how can I avoid this.

Answer 1

I don’t think you’ve actually got a thread-local variable here – you’ve just got a race condition because you’re not implementing the singleton pattern properly.

I have a page about the singleton pattern which gives some better options. (In particular, as you’re using the TPL you must be using .NET 4, so the Lazy<T> option is definitely a contender.)