Java Concurrency in Practice

Listings xii Preface xvii Chapter 1: Introduction 1

1.1 A (very) brief history of concurrency 1 1.2 Benefits of threads 3 1.3 Risks of threads 5 1.4 Threads are everywhere 9Part I: Fundamentals 13 Chapter 2: Thread Safety 15

2.1 What is thread safety? 17 2.2 Atomicity 19 2.3 Locking 23 2.4 Guarding state with locks 27 2.5 Liveness and performance 29Chapter 3: Sharing Objects 33

3.1 Visibility 33 3.2 Publication and escape 39 3.3 Thread confinement 42 3.4 Immutability 46 3.5 Safepublication 49Chapter 4: Composing Objects 55

4.1 Designing a thread-safe class 55 4.2 Instance confinement 58 4.3 Delegating thread safety 62 4.4 Adding functionality to existing thread-safe classes 71 4.5 Documenting synchronization policies 74Chapter 5: Building Blocks 79

5.1 Synchronized collections 79 5.2 Concurrent collections 84 5.3 Blocking queues and the producer-consumer pattern 87 5.4 Blocking and interruptible methods 92 5.5 Synchronizers 94 5.6 Building an efficient, scalable result cache 101Part II: Structuring Concurrent Applications 111 Chapter 6: Task Execution 113

6.1 Executing tasks in threads 113 6.2 The Executor framework 117 6.3 Finding exploitable parallelism 123Chapter 7: Cancellation and Shutdown 135

7.1 Task cancellation 135 7.2 Stopping a thread-based service 150 7.3 Handling abnormal thread termination 161 7.4 JVM shutdown 164Chapter 8: Applying Thread Pools 167

8.1 Implicit couplings between tasks and execution policies 167 8.2 Sizing thread pools 170 8.3 Configuring ThreadPoolExecutor 171 8.4 Extending ThreadPoolExecutor 179 8.5 Parallelizing recursive algorithms 181Chapter 9: GUI Applications 189

9.1 Why are GUIs single-threaded? 189 9.2 Short-running GUI tasks 192 9.3 Long-running GUI tasks 195 9.4 Shared data models 198 9.5 Other forms of single-threaded subsystems 202Part III: Liveness, Performance, and Testing 203 Chapter 10: Avoiding Liveness Hazards 205

10.1 Deadlock

Brian Goetz is a software consultant with twenty years industry experience, with over 75 articles on Java development. He is one of the primary members of the Java Community Process JSR 166 Expert Group (Concurrency Utilities), and has served on numerous other JCP Expert Groups.

Tim Peierls is the very model of a modern multiprocessor, with BoxPop.biz, recording arts, and goings on theatrical. He is one of the primary members of the Java Community Process JSR 166 Expert Group (Concurrency Utilities), and has served on numerous other JCP Expert Groups.

Joshua Bloch is a principal engineer at Google and a Jolt Award-winner. He was previously a distinguished engineer at Sun Microsystems and a senior systems designer at Transarc. Josh led the design and implementation of numerous Java platform features, including JDK 5.0 language enhancements and the award-winning Java Collections Framework. He holds a Ph.D. in computer science from Carnegie Mellon University.

Joseph Bowbeer is a software architect at Vizrea Corporation where he specializes in mobile application development for the Java ME platform, but his fascination with concurrent programming began in his days at Apollo Computer. He served on the JCP Expert Group for JSR-166 (Concurrency Utilities).

David Holmes is director of DLTeCH Pty Ltd, located in Brisbane, Australia. He specializes in synchronization and concurrency and was a member of the JSR-166 expert group that developed the new concurrency utilities. He is also a contributor to the update of the Real-Time Specification for Java, and has spent the past few years working on an implementation of that specification. Doug Lea is one of the foremost experts on object-oriented technology and software reuse. He has been doing collaborative research with Sun Labs for more than five years. Lea is Professor of Computer Science at SUNY Oswego, Co-director of the Software Engineering Lab at the New York Center for Advanced