wp8 PeriodicTask and persisted storage

Question

I have a PeriodicTask that updates a tile for my phone app and saves the information to persisted storage.

This works fine until the list gets to around a size of 11 or 12.

The objects that I save is a poco object with about 5 members. I basiclly get data, save data and create tile (not shown).

so

//get data
var newData = GetPocoFromWeb();
base.Add(newData); 

the base class

     public abstract class DataFetcher<T> where T : IDataCarrier, new()
        {
            protected readonly IPersist<List<T>> Persist;
            protected DataFetcher(IPersist<List<T>> persist)
            {
                Persist = persist;
            }

            protected void Add(T item)
            {
                var items = Persist.Load();
                items.Add(item);
                Persist.Save(items);
            }
        }

The persist class

public class Persist<T> : IPersist<T>
    {
        private readonly string _identifier;

        public Persist(string identifier)
        {
            _identifier = identifier;
        }

        public virtual T Load()
        {
            if (IsolatedStorageSettings.ApplicationSettings.Contains(_identifier))
            {
                return (T)IsolatedStorageSettings.ApplicationSettings[_identifier];
            }

            return default(T);
        }

        public virtual void Save(T item)
        {
            IsolatedStorageSettings.ApplicationSettings[_identifier] = item;
            IsolatedStorageSettings.ApplicationSettings.Save();
        }  

    }

Am I perhaps using wrong storage? 11 items in a list isn't really that many.

Update: When I load the list and add to it using the application (not through the periodicTask) i can easily save several hundred items.

I don't get any error when running in emulator, it just works till the list has around 11 items and then stops working.

Answer 1

You don't go into much detail into what error you are getting (if any), so it's difficult to say.

Having said that, here's a few things that come to mind:

• If you call NotifyComplete() before the asynchronous call completes , you may be being shut down before you have the chance
• Background tasks only have 6mb of memory (12mb on WP8). If you go over it your process will be terminated
• Background tasks only have 25 seconds or so to execute. If you continue past this your process will be terminated.
• Don't use the IsolatedStorageSettings class to share state between processes
• You should be using a Mutex to protect process-process access to your storage.

Answer 2

What exactly is the problem you're experiencing? Using IsolatedStorageSettings shouldn't restrict the size of the list you're able to persist.