带有 BlockingCollection.GetConsumableEnumerable 的 Parallel.ForEach 循环

Question

Why Parallel.ForEach loop exits with OperationCancelledException , while using GetConsumableEnumerable ?

//outside the function
static BlockingCollection<double> _collection = new BlockingCollection<double>();
    
    
var t = Task.Factory.StartNew(Producer);            
Parallel.ForEach(_collection.GetConsumingEnumerable(),
    item => Console.WriteLine("Processed {0}", item));
Console.WriteLine("FINISHED processing");


public static void Producer()
{
     var data = Enumerable.Range(1, 1000);
     foreach (var i in data)
     {
        _collection.Add(i);
        Console.WriteLine("Added {0}",i);
     }
                    
     Console.WriteLine("Finished adding");
     _collection.CompleteAdding();
}

Answer 1

Using Parallel.ForEach with BlockingCollection is somewhat problematic, as I found out recently. It can be made to work, but it needs a little extra effort.

Stephen Toub has an excellent blog post on it , and if you download the "Parallel Extension Extras" project ( also available on NuGet ) you'll find some code ready to help you.