C# 9.0 in a Nutshell

Chapter 14. Concurrency and Asynchrony

Most applications need to deal with more than one thing happening at a time (concurrency). In this chapter, we start with the essential prerequisites, namely the basics of threading and tasks, and then describe in detail the principles of asynchrony and C#’s asynchronous functions.

In Chapter 21, we revisit multithreading in greater detail, and in Chapter 22, we cover the related topic of parallel programming.

Introduction

Following are the most common concurrency scenarios:

Writing a responsive user interface

In Windows Presentation Foundation (WPF), mobile, and Windows Forms applications, you must run time-consuming tasks concurrently with the code that runs your user interface to maintain responsiveness.

Allowing requests to process simultaneously

On a server, client requests can arrive concurrently and so must be handled in parallel to maintain scalability. If you use ASP.NET Core or Web API, the runtime does this for you automatically. However, you still need to be aware of shared state (for instance, the effect of using static variables for caching).

Parallel programming

Code that performs intensive calculations can execute faster on multicore/multiprocessor computers if the workload is divided between cores (Chapter 22 is dedicated to this).

Speculative execution

On multicore machines, you can sometimes improve performance by predicting something that might need to be done and then doing it ahead of time. LINQPad uses this technique ...