C # parallel extensions Task.Factory.StartNew calls a method on the wrong object

Question

Ok, playing with .Net 4.0 Parellel Extensions in System.Threading.Tasks. I find what seems to be strange behavior, but I believe that I am doing something wrong. I have an interface and a couple of implementing clans, they are just for that.

interface IParallelPipe
{
    void Process(ref BlockingCollection<Stream> stream, long stageId);
}

class A:IParallelPipe
{
    public void Process(ref BlockingCollection<Stream> stream, long stageId)
    {
        //do stuff
    }
}

class B:IParallelPipe
{
    public void Process(ref BlockingCollection<Stream> stream, long stageId)
    {
        //do stuff
    }
}

Then I have a class that runs everything on them. This is where the problem arises. I essentially get information about what the implementing class calls from the passed type, and then calls the factory to create it, and then create a task with it and start it. Shown here:

BlockingCollection<Stream> bcs = new BlockingCollection<Stream>();                   
foreach (Stage s in pipeline.Stages) 
{
    IParallelPipe p = (IParallelPipe)Factory.GetPipe(s.type);
    Task.Factory.StartNew(() => p.Process(ref bcs, s.id)); 
}

.Stages : , A, B. , te, p . B , A.Process(...). stageId , (.. stageIds).

, , , - :

BlockingCollection<Stream> bcs = new BlockingCollection<Stream>();                   
A a = null;
B b = null;
foreach (Stage s in pipeline.Stages) 
{
    IParallelPipe p = (IParallelPipe)Factory.GetPipe(s.type);
    if(p is A)
        a = p;
    else
        b = p;
}
Task.Factory.StartNew(() => a.Process(ref bcs, idThatINeed)); 
Task.Factory.StartNew(() => b.Process(ref bcs, idThatINeed));

!

???

Answer 1

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:

BlockingCollection<Stream> bcs = new BlockingCollection<Stream>();
foreach (Stage s in pipeline.Stages) 
{
    Stage copy = s;
    IParallelPipe p = (IParallelPipe)Factory.GetPipe(s.type);
    Task.Factory.StartNew(() => p.Process(ref bcs, copy.id)); 
}

, , "" .

, :

BlockingCollection<Stream> bcs = new BlockingCollection<Stream>();
foreach (Stage s in pipeline.Stages) 
{
    long id = s.id;
    IParallelPipe p = (IParallelPipe)Factory.GetPipe(s.type);
    Task.Factory.StartNew(() => p.Process(ref bcs, id)); 
}

, , , ? .