Question

This is what my loop looks like:

var loopResult = Parallel.ForEach(folder.Items.Cast<object>(), (item, loopState) =>
    {
        if (!loadData)
        {
            loopState.Stop();
            return;
        }

        DoSomeWork(item);
    }
);

if (loopResult.IsCompleted)
{
    Debug.WriteLine("done");
}

The problem is the code never gets to if (loopResult.IsCompleted). After executing return; for all the different threads, absolutely nothing happens.

Answer 1

The code never gets to the body of if (loopResult.IsCompleted) because the parallel loop has been stopped successfully. You can check it as follows:

/* ForEach loop as above */

if (!loopResult.IsCompleted && 
         !loopResult.LowestBreakIteration.HasValue)
{
   Debug.WriteLine("Loop was stopped");
}

if (loopResult.IsCompleted)
{
    Debug.WriteLine("Loop was done without stopping");
}

You can find useful information how to Stop/Break a parallel loop in this MSDN page, starting from Breaking Out of Loops Early subsection.