|Java Concurrency in Practice||
Java Concurrency in Practice
As processors become faster and multiprocessor systems become cheaper, the
need to take advantage of multithreading in order to achieve full hardware
resource utilization only increases the importance of being able to incorporate
concurrency in a wide variety of application categories. For many developers,
concurrency remains a mystery. Developing, testing and debugging
multithreaded programs is extremely difficult because concurrency hazards do
not manifest themselves uniformly or reliably. This book is intended to be
neither an introduction to concurrency (any threading chapter in an 'intro'
book does that) nor is it an encyclopedic reference of All Things Concurrency
(that would be Doug Lea's Concurrent Programming in Java). Instead, this title
is a combination of concepts, guidelines, and examples intended to assist
developers in the difficult process of understanding concurrency and its new
tools in J2SE 5.0. Filled with contributions from Java gurus such as Josh Bloch,
David Holmes and Doug Lea, this book provides any Java programmers with
the basic building blocks they need to gain a basic understanding of
concurrency and its benefits.
A how-to companion to Doug Lea's 'Concurrent Programming in Java', this book is the only authorative and practical guide to Java Concurrency
° Powerhouse author team with contributions from Doug Lea, Josh Bloch and David Holmes
° A practical, hands-on, example-driven guide for every working Java programmer
° Based on J2SE 5.0 which includes many new concurrency features that make concurrency development much more accesible (and necessary)
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 9
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 29
3.1 Visibility 33
3.2 Publication and escape 39
3.3 Thread confinement 42
3.4 Immutability 46
3.5 Safepublication 49
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 74
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 101
6.1 Executing tasks in threads 113
6.2 The Executor framework 117
6.3 Finding exploitable parallelism 123
7.1 Task cancellation 135
7.2 Stopping a thread-based service 150
7.3 Handling abnormal thread termination 161
7.4 JVM shutdown 164
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 181
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 202
10.1 Deadlock 205
10.2 Avoiding and diagnosing deadlocks 215
10.3 Other liveness hazards 218
11.1 Thinking about performance 221
11.2 Amdahl's law 225
11.3 Costs introduced by threads 229
11.4 Reducing lock contention 232
11.5 Example: Comparing Map performance 242
11.6 Reducing context switch overhead 243
12.1 Testing for correctness 248
12.2 Testing for performance 260
12.3 Avoiding performance testing pitfalls 266
12.4 Complementary testing approaches 270
13.1 Lock and ReentrantLock 277
13.2 Performance considerations 282
13.3 Fairness 283
13.4 Choosing between synchronized and ReentrantLock 285
13.5 Read-write locks 286
14.1 Managing state dependence 291
14.2 Using condition queues 298
14.3 Explicit condition objects 306
14.4 Anatomy of a synchronizer 308
14.5 AbstractQueuedSynchronizer 311
14.6 AQS in java.util.concurrent synchronizer classes 314
15.1 Disadvantages of locking 319
15.2 Hardware support for concurrency 321
15.3 Atomic variable classes 324
15.4 Nonblocking algorithms 329
16.1 What is a memory model, and why would I want one? 337
16.2 Publication 344
16.3 Initialization safety 349
A.1 Class annotations 353
A.2 Field andmethod annotations 353
'I was fortunate indeed to have worked with a fantastic team on the design and implementation of the concurrency features added to the Java platform in Java 5.0 and Java 6. Now this same team provides the best explanation yet of these new features, and of concurrency in general. Concurrency is no longer a subject for advanced users only. Every Java developer should read this book.'
JDK Concurrency Czar, Sun Microsystems
'For the past 30 years, computer performance has been driven by Moore's Law; from now on, it will be driven by Amdahl's Law. Writing code that effectively exploits multiple processors can be very challenging. Java Concurrency in Practice provides you with the concepts and techniques needed to write safe and scalable Java programs for today's--and tomorrow's--systems.'
Research Scientist, Intel Corp
'This is the book you need if you're writing--or designing, or debugging, or maintaining, or contemplating--multithreaded Java programs. If you've ever had to synchronize a method and you weren't sure why, you owe it to yourself and your users to read this book, cover to cover.'
Author of Effective Enterprise Java
'Brian addresses the fundamental issues and complexities of concurrency with uncommon clarity. This book is a must-read for anyone who uses threads and cares about performance.'
'This book covers a very deep and subtle topic in a very clear and concise way, making it the perfect Java Concurrency reference manual. Each page is filled with the problems (and solutions!) that programmers struggle with every day. Effectively exploiting concurrency is becoming more and more important now that Moore's Law is delivering more cores but not faster cores, and this book will show you how to do it.'
--Dr. Cliff Click
Senior Software Engineer, Azul Systems
'I have a strong interest in concurrency, and have probably written more thread deadlocks and made more synchronization mistakes than most programmers. Brian's book is the most readable on the topic of threading and concurrency in Java, and deals with this difficult subject with a wonderful hands-on approach. This is a book I am recommending to all my readers of The Java Specialists' Newsletter, because it is interesting, useful, and relevant to the problems facing Java developers today.'
--Dr. Heinz Kabutz
The Java Specialists' Newsletter
'I've focused a career on simplifying simple problems, but this book ambitiously and effectively works to simplify a complex but critical subject: concurrency. Java Concurrency in Practice is revolutionary in its approach, smooth and easy in style, and timely in its delivery--it's destined to be a very important book.'
Author of Beyond Java
'Java Concurrency in Practice is an invaluable compilation of threading know-how for Java developers. I found reading this book intellectually exciting, in part because it is an excellent introduction to Java's concurrency API, but mostly because it captures in a thorough and accessible way expert knowledge on threading not easily found elsewhere.'
Author of Inside the Java Virtual Machine
Threads are a fundamental part of the Java platform. As multicore processors become the norm, using concurrency effectively becomes essential for building high-performance applications. Java SE 5 and 6 are a huge step forward for the development of concurrent applications, with improvements to the Java Virtual Machine to support high-performance, highly scalable concurrent classes and a rich set of new concurrency building blocks. In Java Concurrency in Practice, the creators of these new facilities explain not only how they work and how to use them, but also the motivation and design patterns behind them
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 Technology in Computer Applications, and Adjunct Professor of Electrical and Computer Engineering at Syracuse University. In addition, he co-authored the book, Object-Oriented System Development (Addison-Wesley, 1993). He received his B.A., M.A., and Ph.D. from the University of New Hampshire.