Recent C# and .NET developments involve implicitly using asynchrony and concurrency, even when you are not aware of them. This can lead to further problems since many details are usually hidden inside the C# language infrastructure and the .NET base class library APIs. To avoid problems and to be able to create robust applications, a developer has to know exactly what is going on under the hood of asynchrony in .NET.
Besides this, it is important to understand your goals when writing a concurrent application. If it is running on the client, it is usually a good thing to use all the computational resources available so that the application becomes as fast as possible. This involves effective multiple CPU cores usage, and thus requires parallel programming skills. However, if the application is running on the server, it is more important that the server supports as many clients as possible, than the performance of a concrete client request processing. This requires a programmer to distinguish asynchrony from multithreading and have an understanding of scalability.
All these topics will be covered in this book, providing you with enough information to achieve a solid understanding of asynchronous and parallel programming in C#. We will start with basic multithreading concepts, review common concurrent programming problems and solutions, and then we will go through C# and .NET support for writing concurrent applications. Further in the book, we will cover concurrent data structures and patterns, and we will review client-side and server-side concurrency issues. At the end of the book, we will outline the basic principles for creating robust concurrent programs.
Chapter 1, Traditional Concurrency, covers common problems with multithreading and solutions to these problems. You will refresh your knowledge about basic locking techniques and how to make locking more efficient.
Chapter 2, Lock-Free Concurrency, goes further into performance optimization. It covers various ways to write concurrent programs without locking, making the code fast and reliable.
Chapter 3, Understanding Parallelism Granularity, explains another important aspect of organizing your parallel code—splitting a computational workload between threads. It introduces coarse-grained and fine-grained approaches, showing their pros and cons.
Chapter 4, Task Parallel Library in Depth, goes into the details of Task Parallel Library—a framework to organize your concurrent program as a set of related tasks. You will find the internals of TPL reviewed and explained.
Chapter 5, C# Language Support for Asynchrony, is a deep dive into the C# language infrastructure. The chapter shows exactly how the async and await keywords work and how you can write your own await-compatible code.
Chapter 6, Using Concurrent Data Structures, covers the use of data structures in a concurrent program in detail, including standard .NET concurrent collections and custom thread safe collections implementations.
Chapter 7, Leveraging Parallel Patterns, reviews programming patterns related to parallel applications. The chapter describes different kinds of patterns—historical .NET idioms, useful code snippets, and a high-level parallel pipeline pattern.
Chapter 8, Server-Side Asynchrony, is a solution description to the problem of using asynchrony on the server. It explains why it is very important to distinguish asynchrony from parallelism, and how it can affect the scalability and reliability of your server.
Chapter 9, Concurrency in the User Interface, describes the details of how the user interface is implemented, what a message loop is, and why it is very important to keep the UI thread nonblocked.
Chapter 10, Troubleshooting Parallel Programs, explains how to find out what is wrong with your parallel program. You will learn how to write unit tests for an asynchronous code, how to debug it, and find performance bottlenecks.
You will need Visual Studio 2013 or 2015 to run the code samples. For most of the chapters, it will be enough to use the free Visual Studio Community 2013/2015 editions, but the performance test samples will require the Test/Ultimate or Enterprise editions. However, if you cannot use this, it is possible to download the free Apache bench tool to run performance tests as described in the book.
Mastering C# Concurrency is written for existing C# developers who have a knowledge of basic multithreading concepts and want to improve their asynchronous and parallel programming skills. The book covers different topics, from basic concepts to complicated programming patterns and algorithms using the C# and .NET ecosystems. This will be useful to server and client developers, because it covers all the important aspects of using concurrency and asynchrony on both sides.
In this book, you will find a number of styles of text that distinguish between different kinds of information. Here are some examples of these styles, and an explanation of their meaning.
Code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles are shown as follows: "This happens because the Add method of the List<T> class is not thread safe, and the reason for this lies in the implementation details."
A block of code is set as follows:
public void Add(T item)
{
if (_size == _items.Length) EnsureCapacity(_size + 1);
_items[_size++] = item;
_version++;
}When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:
public void Add(T item)
{
if (_size == _items.Length) EnsureCapacity(_size + 1);
_items[_size++] = item;
_version++;
}Any command-line input or output is written as follows:
T2: Add - [T2]: Item 1 T1: Add - [T1]: Item 1 T2: Add - [T2]: Item 2 T2: Add - [T2]: Item 3
New terms and important words are shown in bold. Words that you see on the screen, in menus or dialog boxes for example, appear in the text like this: "Click on Finish and repeat all this for another controller."
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