List thread safety

Question

I am using the below code

var processed = new List();
Parallel.ForEach(items, item => 
{
    processed.Add(SomeProcessingFunc(item));
});
         


        

Answer 1

From Jon Skeet's Book C# in Depth:

As part of Parallel Extensions in .Net 4, there are several new collections in a new System.Collections.Concurrent namespace. These are designed to be safe in the face of concurrent operations from multiple threads, with relatively little locking.

These include:

• IProducerConsumerCollection
• BlockingCollection
• ConcurrentBag
• ConcurrentQueue
• ConcurrentStack
• ConcurrentDictionary
• and others