Table of Contents
Preface vii
1 An Introduction to Concurrency 1
Moore's Law, Web Scale, and the Mess We're In 2
Why Is Concurrency Hard? 4
Race Conditions 4
Atomicity 6
Memory Access Synchronization 8
Deadlocks, Livelocks, and Starvation 10
Determining Concurrency Safety 18
Simplicity in the Face of Complexity 20
2 Modeling Your Code: Communicating Sequential Processes 23
The Difference Between Concurrency and Parallelism 23
What Is CSP? 26
How This Helps You 29
Go's Philosophy on Concurrency 31
3 Go's Concurrency Building Blocks 37
Goroutines 37
The sync Package 47
WaitGroup 47
Mutex and RWMutex 49
Cond 52
Once 57
Pool 59
Channels 64
The select Statement 78
The GOMAXPROCS Lever 83
Conclusion 83
4 Concurrency Patterns in Go 85
Confinement 85
The for select Loop 89
Preventing Goroutine Leaks 90
The or-channel 94
Error Handling 97
Pipelines 100
Best Practices for Constructing Pipelines 104
Some Handy Generators 109
Fan-Out, Fan-In 114
The or-done-channel 119
The lee-channel 120
The bridge-channel 122
Queuing 124
The context Package 131
Summary 145
5 Concurrency at Scale 147
Error Propagation 147
Timeouts and Cancellation 155
Heartbeats 161
Replicated Requests 172
Rate Limiting 174
Healing Unhealthy Goroutines 188
Summary 194
6 Goroutines and the Go Runtime 197
Work Stealing 197
Stealing Tasks or Continuations? 204
Presenting All of This to the Developer 212
Conclusion 212
A Appendix 213
Index 219
