Parallel Programming and Concurrency with C# 10 and .NET 6: A modern approach to building faster, more responsive, and asynchronous .NET applications using C#

Cover....1

Title Page....2

Copyright and Credits....3

Contributors....5

Table of Contents....8

Preface....14

Part 1: Introduction to Threading in .NET....20

Chapter 1: Managed Threading Concepts....22

Technical requirements....23

.NET threading basics....23

Threads and processes....23

When should we use multithreading in .NET?....24

Background threads....24

What is managed threading?....27

Creating and destroying threads....28

Creating managed threads....28

Pausing thread execution....30

Destroying managed threads....32

Handling threading exceptions....32

Synchronizing data across threads....33

Synchronizing code regions....33

Manual synchronization....35

Scheduling and canceling work....37

Scheduling managed threads....37

Canceling managed threads....40

Summary....44

Questions....44

Chapter 2: Evolution of Multithreaded Programming in .NET....46

Technical requirements....47

.NET threading through the years....47

C# 4 and .NET Framework 4.0....47

C# 5 and 6 and .NET Framework 4.5.x....48

C# 7.x and .NET Core 2.0....48

C# 8 and .NET Core 3.0....49

C# 10 and .NET 6....50

Beyond threading basics....50

Managed thread pool....51

Threading and timers....52

Introduction to parallelism....56

Using Parallel.Invoke....57

Using Parallel.ForEach....59

Basics of Parallel LINQ....60

Introduction to concurrency....62

ConcurrentBag....63

ConcurrentQueue....64

ConcurrentStack....64

BlockingCollection....65

ConcurrentDictionary....66

Basics of async and await....66

Understanding the async keyword....66

Writing an async method....67

Choosing the right path forward....69

Summary....70

Questions....70

Chapter 3: Best Practices for Managed Threading....72

Technical requirements....72

Handling static objects....73

Static data and constructors....73

Controlling shared access to static objects....75

Managing deadlocks and race conditions....79

Mitigating deadlocks....80

Avoiding race conditions....82

Threading limits and other recommendations....85

Summary....88

Questions....88

Chapter 4: User Interface Responsiveness and Threading....90

Technical requirements....90

Leveraging background threads....91

Which threads are background threads?....91

Using async, await, tasks, and WhenAll....92

Using the thread pool....101

Updating the UI thread without exceptions....104

Summary....107

Questions....107

Part 2: Parallel Programming and Concurrency with C#....108

Chapter 5: Asynchronous Programming with C#....110

Technical requirements....111

More about asynchronous programming in .NET....111

I/O-bound operations....111

CPU-bound operations....113

Nested async methods....116

Working with Task objects....121

Exploring Task methods....122

Exploring Task properties....124

Interop with synchronous code....125

Executing async from synchronous methods....126

Executing synchronous code as async....129

Working with multiple background tasks....132

Asynchronous programming best practices....133

Summary....134

Questions....135

Chapter 6: Parallel Programming Concepts....136

Technical requirements....136

Getting started with the TPL....137

I/O-bound operations....137

CPU-bound operations....138

Parallel loops in .NET....138

Basic Parallel.For loops....138

Parallel loops with thread-local variables....143

Simple Parallel.ForEach loops....145

Cancel a Parallel.ForEachAsync loop....147

Relationships between parallel tasks....150

Under the covers of Parallel.Invoke....150

Understanding parallel child tasks....151

Common pitfalls with parallelism....156

Parallelism is not guaranteed....156

Parallel loops are not always faster....156

Beware of blocking the UI thread....156

Thread safety....157

UI controls....157

ThreadLocal data....157

Summary....157

Questions....158

Chapter 7: Task Parallel Library (TPL) and Dataflow....160

Technical requirements....161

Introducing the TPL Dataflow library....161

Why use the TPL Dataflow library?....164

Types of dataflow blocks....165

Implementing the producer/consumer pattern....170

Creating a data pipeline with multiple blocks....178

Manipulating data from multiple data sources....182

Summary....184

Questions....184

Chapter 8: Parallel Data Structures and Parallel LINQ....186

Technical requirements....187

Introducing PLINQ....187

PLINQ and performance....188

Creating a PLINQ query....189

Query syntax versus method syntax....190

Converting LINQ queries to PLINQ....191

Handling exceptions with PLINQ queries....193

Preserving data order and merging data with PLINQ....197

PLINQ data order samples....197

Using WithMergeOptions in PLINQ queries....201

Data structures for parallel programming in .NET....205

Concurrent collections....206

Synchronization primitives....206

Summary....207

Questions....208

Chapter 9: Working with Concurrent Collections in .NET....210

Technical requirements....211

Using BlockingCollection....211

BlockingCollection details....211

Using BlockingCollection with Parallel.ForEach and PLINQ....212

Using ConcurrentBag....218

Using ConcurrentDictionary....223

Using ConcurrentQueue....229

Using ConcurrentStack....232

Summary....233

Questions....234

Part 3: Advanced Concurrency Concepts....236

Chapter 10: Debugging Multithreaded Applications with Visual Studio....238

Technical requirements....239

Introducing multithreaded debugging....239

Debugging threads and processes....240

Debugging a project with multiple threads....240

Exploring the Threads window....243

Switching and flagging threads....245

Switching threads....245

Flagging threads....245

Freezing threads....247

Debugging a parallel application....248

Using the Parallel Stacks window....248

Using the Parallel Watch window....253

Summary....257

Questions....257

Chapter 11: Canceling Asynchronous Work....258

Technical requirements....258

Canceling managed threads....259

Canceling parallel work....261

Canceling a parallel loop....262

Canceling a PLINQ query....264

Discovering patterns for thread cancellation....266

Canceling with polling....266

Canceling with callbacks....269

Canceling with wait handles....273

Handling multiple cancellation sources....276

Summary....278

Questions....278

Chapter 12: Unit Testing Async, Concurrent, and Parallel Code....280

Technical requirements....281

Unit testing asynchronous code....281

Unit testing concurrent code....287

Unit testing parallel code....291

Checking for memory leaks with unit tests....295

Summary....299

Questions....300

Assessments....302

Index....308

Other Books You May Enjoy....317

.NET has included managed threading capabilities since the beginning, but early techniques had inherent risks: memory leaks, thread synchronization issues, and deadlocks. This book will help you avoid those pitfalls and leverage the modern constructs available in .NET 6 and C# 10, while providing recommendations on patterns and best practices for parallelism and concurrency. Parallel, concurrent, and asynchronous programming are part of every .NET application today, and it becomes imperative for modern developers to understand how to effectively use these techniques.

This book will teach intermediate-level .NET developers how to make their applications faster and more responsive with parallel programming and concurrency in .NET and C# with practical examples. The book starts with the essentials of multi-threaded .NET development and explores how the language and framework constructs have evolved along with .NET. You will later get to grips with the different options available today in .NET 6, followed by insights into best practices, debugging, and unit testing.

By the end of this book, you will have a deep understanding of why, when, and how to employ parallelism and concurrency in any .NET application.

What You Will Learn:

• Prevent deadlocks and race conditions with managed threading
• Update Windows app UIs without causing exceptions
• Explore best practices for introducing asynchronous constructs to existing code
• Avoid pitfalls when introducing parallelism to your code
• Implement the producer-consumer pattern with Dataflow blocks
• Enforce data sorting when processing data in parallel and safely merge data from multiple sources
• Use concurrent collections that help synchronize data across threads
• Debug an everyday parallel app with the Parallel Stacks and Parallel Tasks windows

Who this book is for:

This book is for beginner to intermediate-level .NET developers who want to employ the latest parallel and concurrency features in .NET when building their applications. Readers should have a solid understanding of the C# language and any version of the .NET Framework or .NET Core.