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

205 Pages·2014·9.347 MB·English

by  Stephen Cleary

Praise for Concurrency in C# Cookbook
“The next big thing in computing is making massive parallelism accessible to mere mortals.
Developers have more power available to us than ever before, but expressing concurrency
is still a challenge for many. Stephen turns his attention to this problem, helping us all better
understand concurrency, threading, reactive programming models, parallelism, and much
more in an easy-to-read but complete reference.”
— Scott Hanselman
Principal Program Manager, ASP.NET and Azure Web Tools,
Microsoft
“The breadth of techniques covered and the cookbook format make this the ideal reference
book for modern .NET concurrency.”
— Jon Skeet
Senior Software Engineer at Google
“Stephen Cleary has established himself as a key expert on asynchrony and parallelism in
C#. This book clearly and concisely conveys the most important points and principles
developers need to understand to get started and be successful with these technologies.”
— Stephen Toub
Principal Architect, Microsoft

Concurrency in C# Cookbook
Stephen Cleary
Concurrency in C# Cookbook
by Stephen Cleary
Copyright © 2014 Stephen Cleary. All rights reserved.
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June 2014: First Edition
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2014-05-14: First release
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ISBN: 978-1-449-36756-5
[Q]
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 15
2. Async Basics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
2.1. Pausing for a Period of Time 18
2.2. Returning Completed Tasks 20
2.3. Reporting Progress 21
2.4. Waiting for a Set of Tasks to Complete 22
2.5. Waiting for Any Task to Complete 25
2.6. Processing Tasks as They Complete 26
2.7. Avoiding Context for Continuations 30
2.8. Handling Exceptions from async Task Methods 31
2.9. Handling Exceptions from async Void Methods 32
3. Parallel Basics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
3.1. Parallel Processing of Data 35
3.2. Parallel Aggregation 37
3.3. Parallel Invocation 39
3.4. Dynamic Parallelism 40
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3.5. Parallel LINQ 42
4. Dataflow Basics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
4.1. Linking Blocks 46
4.2. Propagating Errors 47
4.3. Unlinking Blocks 49
4.4. Throttling Blocks 50
4.5. Parallel Processing with Dataflow Blocks 51
4.6. Creating Custom Blocks 52
5. Rx Basics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
5.1. Converting .NET Events 56
5.2. Sending Notifications to a Context 58
5.3. Grouping Event Data with Windows and Buffers 60
5.4. Taming Event Streams with Throttling and Sampling 62
5.5. Timeouts 64
6. Testing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
6.1. Unit Testing async Methods 68
6.2. Unit Testing async Methods Expected to Fail 69
6.3. Unit Testing async void Methods 71
6.4. Unit Testing Dataflow Meshes 72
6.5. Unit Testing Rx Observables 74
6.6. Unit Testing Rx Observables with Faked Scheduling 76
7. Interop. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
7.1. Async Wrappers for “Async” Methods with “Completed” Events 81
7.2. Async Wrappers for “Begin/End” methods 83
7.3. Async Wrappers for Anything 84
7.4. Async Wrappers for Parallel Code 86
7.5. Async Wrappers for Rx Observables 87
7.6. Rx Observable Wrappers for async Code 88
7.7. Rx Observables and Dataflow Meshes 90
8. Collections. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
8.1. Immutable Stacks and Queues 96
8.2. Immutable Lists 98
8.3. Immutable Sets 100
8.4. Immutable Dictionaries 102
8.5. Threadsafe Dictionaries 104
8.6. Blocking Queues 106
8.7. Blocking Stacks and Bags 108
8.8. Asynchronous Queues 110
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8.9. Asynchronous Stacks and Bags 113
8.10. Blocking/Asynchronous Queues 115
9. Cancellation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
9.1. Issuing Cancellation Requests 120
9.2. Responding to Cancellation Requests by Polling 123
9.3. Canceling Due to Timeouts 124
9.4. Canceling async Code 125
9.5. Canceling Parallel Code 126
9.6. Canceling Reactive Code 128
9.7. Canceling Dataflow Meshes 130
9.8. Injecting Cancellation Requests 131
9.9. Interop with Other Cancellation Systems 132
10. Functional-Friendly OOP. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
10.1. Async Interfaces and Inheritance 135
10.2. Async Construction: Factories 137
10.3. Async Construction: The Asynchronous Initialization Pattern 139
10.4. Async Properties 142
10.5. Async Events 145
10.6. Async Disposal 148
11. Synchronization. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153
11.1. Blocking Locks 158
11.2. Async Locks 160
11.3. Blocking Signals 162
11.4. Async Signals 163
11.5. Throttling 165
12. Scheduling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167
12.1. Scheduling Work to the Thread Pool 167
12.2. Executing Code with a Task Scheduler 169
12.3. Scheduling Parallel Code 171
12.4. Dataflow Synchronization Using Schedulers 172
13. Scenarios. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173
13.1. Initializing Shared Resources 173
13.2. Rx Deferred Evaluation 175
13.3. Asynchronous Data Binding 176
13.4. Implicit State 178
Index. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181
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