76 of 78 people found the following review helpful
5.0 out of 5 stars
The definitive book on concurrency in Java, May 28 2006
By calvinnme - Published on Amazon.com
This review is from: Java Concurrency in Practice (Paperback)
Concurrency, in the form of threads, has been present in the Java language from its beginning, and this book is all about concurrency in the current and future versions of Java with an emphasis on writing practical code. This book does for concurrent programming in Java what Geary's series of books did for graphical Java - it moves concurrent Java programming out of the realm of applets containing bouncing balls and into that of providing real solutions for professional programmers.
This book is not meant to be an introduction to concurrency in Java. Its intention is to offer practical design rules to assist developers in the difficult process of creating safe, fast, and high-performance concurrent classes. While many of the general concepts in this book are applicable to versions of Java prior to Java 1.5, most of the code examples and all the statements about the Java Memory Model assume Java 1.5 or later. By "later" I mean that some of the code examples use library features added in the not-yet released Java 1.6. After the introduction, which consists of Chapter 1, the book is divided into four parts:
Part one, "Fundamentals", (Chapters 2-5) are about the basic concepts of concurrency, thread safety, and composing thread-safe classes from those concurrent building blocks provided by the Java language. Chapter 2, "Thread Safety", and 3, "Sharing Objects", include nearly all of the rules on avoiding concurrency hazards, constructing thread-safe classes, and verifying thread safety. Thus, these chapters emphasize theory and have less code than other chapters in the book. Chapter 4 , "Composing Objects", covers techniques for composing large thread-safe classes from smaller thread-safe classes. Chapter 5, "Building Blocks", covers thread-safe collections and synchronizers, which are the the concurrent building blocks provided by Java. To conclude the section, the authors work through the steps of building an efficient, scalable result cache that could be used in a web server. A summary of the most important rules presented in Part one occur at the end of the section.
Part two, "Structuring Concurrent Applications", describes how proper use of threading improves the throughput and responsiveness of concurrent applications. The topics covered in this section include identifying tasks that can be run in parallel and programming them as such, proper termination of tasks, using thread pools for greater efficiency in multi-threaded systems, and finally improving the responsiveness of single-threaded systems, GUI's being the most prominent example.
Part 3, "Liveness, Performance, and Testing" is concerned with ensuring that concurrent programs actually do what is expected of them and do so with acceptable performance. The authors describe how to avoid situations where a thread waits forever, also known as a "liveness failure". Also included in this section is an excellent explanation of the use of the "ThreadLocal" class and how it makes it much easier to manage the process of associating a thread with its per-thread data.
Part 4, "Advanced Topics", covers issues that will probably be interesting only to experienced developers. These topics include explicit locks, atomic variables, nonblocking algorithms, and developing custom synchronizers. Any of these techniques, explicit locks in particular, can cause chaos when done incorrectly. This book shows how to use these techniques safely and with confidence.
One of the things that makes this book so good are the many code examples. There are only snippets of entire programs included in the book itself in order to highlight the portions relevant to the concurrency issue being discussed. The code examples are either good examples, questionable examples, or bad code examples and are decorated with "Smiley Faces" that are either happy, concerned, or unhappy depending on the quality of the code. The full versions of the code examples, as well as supplementary examples and errata, are supposed to be available from the book's website. However, at the time I am writing this, they are not yet available.
Overall, I would say that this is the most complete and accessible resource on concurrency in Java I have seen in print. I highly recommend it.
28 of 29 people found the following review helpful
5.0 out of 5 stars
At last! A readable, expert book on Java concurrency, Aug 7 2006
By Thing with a hook - Published on Amazon.com
This review is from: Java Concurrency in Practice (Paperback)
Concurrency is hard and boring. Unfortunately, my favoured technique of ignoring it and hoping it will go away doesn't look like it's going to bear fruit. Fortunately, Java 5.0 introduced a new bunch of concurrency utilities, that work at a higher level of abstraction than marking blocks as synchronized and fields as volatile. Unfortunately, there haven't been that many books on the subject - even the good Java 5.0 books (e.g. Head First Java or Agile Java) make little mention of them - Thinking in Java being an honourable exception. Fortunately, JCIP is here, and it is authoritative stuff. And it's (mostly) very easy to understand. Plus, at 350 pages, it's not an enormous chore to slog through. It even covers changes to the upcoming Java 6.
Before tackling this book, you should have at least some idea of pre-Java 5.0 concurrency. You don't need to be a threading master, though, as the first part of the book covers basics like deadlock, atomicity and liveness. This was my favourite part of the book, as it comes with lots of small code snippets, both right and (horribly) wrong, and pithy design guidelines. It's rather like Effective Java in that respect - although the material on threading was probably the weakest part of that book, so this is a definite improvement.
The second part deals with thread pools, cancellation strategies, and GUIs. This is also excellent. Part three covers performance and testing. The last 75 pages are for advanced users and goes into a fair amount of low level detail (including a discussion of the Java Memory Model), which may be of interest to experts only.
I would be lying if I said that reading this book will demystify concurrency completely. Who wrote which bit of the book is unclear (although readers of Effective Java will probably spot parts of the text that seem rather Joshua Blochish), but while it's mostly very clear, some parts of the text are a little murkier than other. Perhaps this is to be expected given the subject matter. But for the most part it's surprisingly easy reading, and very practical to boot.
Let's face it, short of aliens landing and introducing a radically new way of computing, multicores are here for the medium term at least, so thread-dodging wimps such as myself will just have to get used to it. That being so, this book is going to be installed as one of the must-read books in the Java pantheon.
31 of 35 people found the following review helpful
5.0 out of 5 stars
Excellent coverage of Java multi-threading, Jun 2 2006
By Kyrill Alyoshin - Published on Amazon.com
This review is from: Java Concurrency in Practice (Paperback)
The book is by far the best one on Java concurrency. There is really nothing out there that has such comprehensive coverage of this topic. Doug Lee's book is a bit theoretical and somewhat dry, but would be a nice complement to this book if you want to think some more about concurrency. This book has a very strong practical vector. Coverage of Java 5 concurrency features is very thorough. The book is extremely well-written, relatively easy to read.
The book stands on par with such established Java book jems as Josh Bloch's "Effective Java", Eckel's "Thinking in Java" and Rod Johnson's J2EE books.
All in all, this is a definite must have for any Java specialist.