Concurrency in C# Cookbook: Asynchronous, Parallel, and Multithreaded Programming

by Stephen Cleary

Overview

If you’re one of many developers still uncertain about concurrent and multithreaded development, this practical cookbook will change your mind. With more than 85 code-rich recipes in this updated second edition, author Stephen Cleary demonstrates parallel processing and asynchronous programming techniques using libraries and language features in .NET and C# 8.0.

Concurrency is now more common in responsive and scalable application development, but it’s still extremely difficult to code. The detailed solutions in this cookbook show you how modern tools raise the level of abstraction, making concurrency much easier than before. Complete with ready-to-use code and discussions about how and why solutions work, these recipes help you:

• Get up to speed on concurrency and async and parallel programming
• Use async and await for asynchronous operations
• Enhance your code with asynchronous streams
• Explore parallel programming with .NET’s Task Parallel Library
• Create dataflow pipelines with .NET’s TPL Dataflow library
• Understand the capabilities that System.Reactive builds on top of LINQ
• Utilize threadsafe and immutable collections
• Learn how to conduct unit testing with concurrent code
• Make the thread pool work for you
• Enable clean, cooperative cancellation
• Examine scenarios for combining concurrent approaches
• Dive into asynchronous-friendly object-oriented programming
• Recognize and write adapters for code using older asynchronous styles

Product Details

ISBN-13:	9781492054504
Publisher:	O'Reilly Media, Incorporated
Publication date:	09/10/2019
Edition description:	2nd ed.
Pages:	251
Product dimensions:	6.90(w) x 9.00(h) x 0.70(d)

About the Author

Stephen Cleary is a developer with extensive experience ranging from ARM firmware to Azure. He has contributed to open source from the very beginning, starting with the Boost C++ libraries, and has released several libraries and utilities of his own.

Table of Contents

Preface vii

1 Concurrency: An Overview 1

1.1 Introduction to Concurrency 1

1.2 Introduction to Asynchronous Programming 3

1.3 Introduction to Parallel Programming 7

1.4 Introduction to Reactive Programming (Rx) 10

1.5 Introduction to Dataflows 12

1.6 Introduction to Multithreaded Programming 14

1.7 Collections for Concurrent Applications 15

1.8 Modern Design 15

1.9 Summary of Key Technologies 16

2 Async Basics 19

2.1 Pausing for a Period of Time 20

2.2 Returning Completed Tasks 22

2.3 Reporting Progress 23

2.4 Waiting for a Set of Tasks to Complete 24

2.5 Waiting for Any Task to Complete 27

2.6 Processing Tasks as They Complete 28

2.7 Avoiding Context for Continuations 32

2.8 Handling Exceptions from async Task Methods 33

2.9 Handling Exceptions from async Void Methods 34

3 Parallel Basics 37

3.1 Parallel Processing of Data 37

3.2 Parallel Aggregation 39

3.3 Parallel Invocation 41

3.4 Dynamic Parallelism 42

3.5 Parallel LINQ 44

4 Dataflow Basks 47

4.1 Linking Blocks 48

4.2 Propagating Errors 49

4.3 Unlinking Blocks 51

4.4 Throttling Blocks 52

4.5 Parallel Processing with Dataflow Blocks 53

4.6 Creating Custom Blocks 54

5 Rx Basics 57

5.1 Converting .NET Events 58

5.2 Sending Notifications to a Context 60

5.3 Grouping Event Data with Windows and Buffers 62

5.4 Taming Event Streams with Throttling and Sampling 64

5.5 Timeouts 66

6 Testing 69

6.1 Unit Testing async Methods 70

6.2 Unit Testing async Methods Expected to Fail 71

6.3 Unit Testing async void Methods 73

6.4 Unit Testing Dataflow Meshes 74

6.5 Unit Testing Rx Observables 76

6.6 Unit Testing Rx Observables with Faked Scheduling 78

7 Interop 83

7.1 Async Wrappers for "Async" Methods with "Completed" Events 83

7.2 Async Wrappers for "Begin/End" methods 85

7.3 Async Wrappers for Anything 86

7.4 Async Wrappers for Parallel Code 88

7.5 Async Wrappers for Rx Observables 89

7.6 Rx Observable Wrappers for async Code 90

7.7 Rx Observables and Dataflow Meshes 92

8 Collections 95

8.1 Immutable Stacks and Queues 98

8.2 Immutable Lists 100

8.3 Immutable Sets 102

8.4 Immutable Dictionaries 104

8.5 Threadsafe Dictionaries 106

8.6 Blocking Queues 108

8.7 Blocking Stacks and Bags 110

8.8 Asynchronous Queues 112

8.9 Asynchronous Stacks and Bags 115

8.10 Blocking/Asynchronous Queues 117

9 Cancellation 121

9.1 Issuing Cancellation Requests 122

9.2 Responding to Cancellation Requests by Polling 125

9.3 Canceling Due to Timeouts 126

9.4 Canceling async Code 127

9.5 Canceling Parallel Code 128

9.6 Canceling Reactive Code 130

9.7 Canceling Dataflow Meshes 132

9.8 Injecting Cancellation Requests 133

9.9 Interop with Other Cancellation Systems 134

10 Functional-Friendly OOP 137

10.1 Async Interfaces and Inheritance 137

10.2 Async Construction: Factories 139

10.3 Async Construction: The Asynchronous Initialization Pattern 141

10.4 Async Properties 144

10.5 Async Events 147

10.6 Async Disposal 150

11 Synchronization 155

11.1 Blocking Locks 160

11.2 Async Locks 162

11.3 Blocking Signals 164

11.4 Async Signals 165

11.5 Throttling 167

12 Scheduling 169

12.1 Scheduling Work to the Thread Pool 169

12.2 Executing Code with a Task Scheduler 171

12.3 Scheduling Parallel Code 173

12.4 Dataflow Synchronization Using Schedulers 174

13 Scenarios 175

13.1 Initializing Shared Resources 175

13.2 Rx Deferred Evaluation 177

13.3 Asynchronous Data Binding 178

13.4 Implicit State 180

Index 183