CODEWITHSUNDEEP
c#.netlinqtask-parallel-library
Everything Matters
Everything Matters

Reputation: 2720

Using Parallel.Foreach Inside A Thread

I have a thread that loads data when a service is starting. I call a method in this thread that uses Parallel.Foreach to iterate a set of data. But the linq query that I have inside the parallel forerach, gets a objet reference not set to an instance error.

*The same logic works if I remove the Parallel.Foreach though or if I remove the thread. *Even locking the list doesnt help.**

    loadingThread = new Thread(new ThreadStart(PreloadData));
                loadingThread.IsBackground = true;
                loadingThread.Start();
---------------------------------------

    public static void PreloadData()
    {
     Parallel.ForEach(loadedIDs.Keys, indexDefId =>
                    {
                        List<FixingEvent> lst = null;
                        lock (loadedEvents)
                        {
                            lst = (from e in loadedEvents where e.DIVACode.Equals(indexDefId) select e).ToList();
                        }

---------------------------
    }

I get an exception in the linq query inside - ' e is null and hence object reference error'.

Any help is appreciated.

Upvotes: 1

Views: 1165

Answers (2)

Paul
Paul

Reputation: 1875

You should not lock the loadedEvents object. According to msdn:

Best practice is to define a private object to lock on, or a private static object variable to protect data common to all instances.

you do not need to lock the object you are accessing - you simply need an object to lock on.

Upvotes: 1

usr
usr

Reputation: 171178

I guess the list loadedEvents contains null elements. Maybe due to a race condition.

Upvotes: 0

Related Questions