Parallel.ForEach and Parallel.Invoke

Parallel.ForEach method is the parallel equivalent to "serial" foreach loop. It Iterates on a collection of generic type parameter type TSource. You can pass three different collection types: System.Collections.Generic.IEnumerable, System.Collections.Concurrent.Partitioner and System.Collections.Concurrent.OrderablePartitioner. Partioner classes are abstract and are here to write custom partioning code. This topic is beyond the scope of this post, and leave it for the future.
Here is a quick example of how to use this overload of Parallel.ForEach:

ints is IEnumerable and a is an object from this IEnumerable instance. You can use other Stop and Break semantics by replacing the second parameter with other delegate:
Action. and use the ParallelLoopState.Stop or ParallelLoopState.Break to exit from "loop" at the earliest convenience.
Lastly, lets see what's the Parallel.Invoke method has to offer. It takes a variable number of Action delegates, and executes them in parallel. Here is a quick example:

Task1,Task2,Task3,Task4 are dumb methods whose signature matches the Action delegate's, Just to show an example.