C# Tutorial: Concurrent Programming

[BillWagner]

This issue tracks the creation of this topic: https://github.com/dotnet/docs/blob/master/docs/csharp/tutorials/concurrent-programming.md

This tutorial should explain techniques for running CPU bound tasks in parallel for increased throughput.

This tutorial must contrast concurrent programming with asynchronous programming. It should explore techniques like Parallel LINQ, the TPL and related libraries that enable parallel work.

Some discussion of shared data, and why mutable shared data is harmful should be included.

The basics of accessing data in a thread safe manner should be covered. Add caveats that these are basics, and not a complete treatment.