Book excerpt: Executing tasks in threads
Learn how to execute tasks in threads in this excerpt from Java Concurrency in Practice (Brian Goetz et al. (Addison Wesley Professional, May 2006)). The authors present the Executor interface as the basis for a flexible and powerful framework for asynchronous task execution that supports a wide variety of task execution policies.
Brian Goetz, Tim Peierls, Joshua Bloch, Joseph Bowbeer, David Holmes and Doug Lea, September 2006

Is your code ready for the next wave in commodity computing?
We are standing on the cusp of a real sea change in commodity hardware architectures—the move away from individual processing units that run at high speeds and temperatures to a team of connected units that individually (now at least) are less powerful, but make up for that several times over in sheer numbers. This shift is pervasive, from Unix servers to game consoles. Read on as Humphrey Sheil maps out the history of parallelism, examines the current hardware offerings from the main vendors, looks at some of the seminal software theory, and identifies the strong and weak areas of the Java platform as they relate to parallelism.
Humphrey Sheil, July 2006

Build application search features modeled on Web searches
Building search features in applications modeled on Web searches provides users with a familiar and intuitive search interface. It keeps the user interface for searching simple and consistent across the application. This article presents a framework that can be used to develop simple yet powerful and extensible searching functionality in applications, more specifically, database-driven applications.
Suneel Parthasarathy, March 2005

Pool resources using Apache's Commons Pool Framework
Resource pooling is not new and is being widely used to conserve and optimize the usage of resources like threads, sockets, and database connections. Web server implementations routinely use thread pool implementations for performance and scalability reasons. Commons Pool, from the Apache Software Foundation, may not be the first when it comes to implementation, but it deserves its own place for defining a framework that allows any arbitrary object to be pooled. This article discusses Commons Pool and shows how to use it to implement a thread pool.
Murali Kosaraju, January 2005

Write thread-safe servlets
You finished your Web application, thoroughly tested it, and it's now deployed. You're feeling bullet proof and 10-feet tall, and then it happens...the customer-support calls start coming in: "We're seeing some strange things. A customer is seeing someone else's information!" As your professional career flashes before your eyes, you scan for any possible scenarios that you may have missed. "Did I test it under load? Could that make a difference? I haven't run into this kind of problem before. Why now?" Well, if you're a Java programmer and developing Web applications, then thread safety is an issue you must contend with regardless of your application type or project size. Your servlet and JavaServer Pages code is subject to thread safety issues due to the way your servlet container uses it. This article presents thread safety in simple terms and explains why it can be an issue for your servlets. You also learn how to avoid writing non-thread-safe servlets and how to make servlets thread-safe.
Phillip Bridgham, July 2004

Customize SwingWorker to improve Swing GUIs
The presentation layer of Swing-based applications mainly consists of event-handling logic, layout properties, and graphical user interface (GUI) components. While such code should be easy to program because of the Swing programming model's single-threaded nature, more complicated concurrent constructs such as SwingWorker are often needed to perform time-consuming tasks while preserving screen liveliness. In this article, Yexin Chen discusses some negative consequences caused by SwingWorker usage and illustrates how to customize SwingWorker to achieve additional architectural design goals.
Yexin Chen, June 2003

Simply Singleton
Sometimes it's appropriate to have exactly one instance of a class: window managers, print spoolers, and filesystems are prototypical examples. Typically, those types of objects—known as singletons—are accessed by disparate objects throughout a software system, and therefore require a global point of access. Of course, just when you're certain you will never need more than one instance, it's a good bet you'll change your mind.
David Geary, April 2003

The thread threat
February 14, 2003
Vladimir Roubtsov, February 2003

Java Tip 132: The taming of the thread
With MutableThread and ThreadWatchDog, you can make your threads come back to life and continue running seamlessly even after thread death.
Roy M. Pueschel, November 2002

Achieve strong performance with threads, Part 4
My previous three articles explored an assortment of thread concepts: the Thread class, the Runnable interface, exceptions and the run() method, synchronization, thread scheduling, the wait/notify mechanism, and thread interruption. This month's Java 101 concludes the thread series by focusing on thread groups, volatility, thread-local variables, timers, and the ThreadDeath class. Want more on threads? The sidebar "Finalization and Threads" describes how various thread concepts combine to finalize objects.
Jeff Friesen, August 2002

Achieve strong performance with threads, Part 3
This month, I continue my four-part thread series by focusing on thread scheduling, the wait/notify mechanism, and thread interruption. You'll investigate how either a JVM or an operating-system thread scheduler chooses the next thread for execution. As you'll discover, priority is important to a thread scheduler's choice. You'll examine how a thread waits until it receives notification from another thread before it continues execution and learn how to use the wait/notify mechanism for coordinating the execution of two threads in a producer-consumer relationship. Finally, you'll learn how to prematurely awaken either a sleeping or a waiting thread for thread termination or other tasks. I'll also teach you how a thread that is neither sleeping nor waiting detects an interruption request from another thread.
Jeff Friesen, July 2002

Study guide: Achieve strong performance with threads, Part 3
Welcome to the Java 101 study guide. This guide complements " Achieve Strong Performance with Threads, Part 3." It provides a glossary of terms specific to that article, tips and cautions, new homework, solutions to last month's homework, and Jeff Friesen's answers to questions from your fellow students. The Java 101 study guides are evolving documents—they change periodically. For example, if you submit a question long after Jeff posts the relevant study guide, your question and his answer will eventually make its way onto that guide. Furthermore, from time to time, he will post additional examples and other material that clarifies an article's topic, so be sure to revisit the study guides periodically.
Jeff Friesen, July 2002

Study guide: Achieve strong performance with threads, Part 4
Welcome to the Java 101 study guide. This guide complements " Achieve Strong Performance with Threads, Part 4." It provides a glossary of terms specific to that article, tips and cautions, new homework, solutions to last month's homework, and Jeff Friesen's answers to questions from your fellow students. The Java 101 study guides are evolving documents—they change periodically. For example, if you submit a question long after Jeff posts the relevant study guide, your question and his answer will eventually make its way onto that guide. Furthermore, from time to time, he will post additional examples and other material that clarifies an article's topic, so be sure to revisit the study guides periodically.
Jeff Friesen, July 2002

Achieve strong performance with threads, Part 2
Is creating multithreaded Java programs hard? With the information gleaned from Part 1 of Java 101's thread series only, you might answer no. After all, last month I showed you how easy it is to create thread objects, start threads that associate with those objects by calling Thread's start() method, and perform simple thread operations by calling other Thread methods, such as the three overloaded join() methods. Yet many developers face difficulty when developing properly behaving multithreaded programs. All too often, their programs function erratically or produce erroneous values. For example, a multithreaded program might store incorrect employee details, such as name and address, in a database. The name might belong to one employee, whereas the address belongs to another. What causes that strange behavior? The lack of synchronization: the act of serializing, or ordering one at a time, thread access to those code sequences that let multiple threads manipulate class and instance field variables, and other shared resources. I call those code sequences critical code sections.
Jeff Friesen, June 2002

Study guide: Achieve strong performance with threads, Part 2
Welcome to the Java 101 study guide. This guide complements " Achieve Strong Performance with Threads, Part 2." It provides a glossary of terms specific to that article, tips and cautions, new homework, solutions to last month's homework, and Jeff Friesen's answers to questions from your fellow students. The Java 101 study guides are evolving documents—they change periodically. For example, if you submit a question long after Jeff posts the relevant study guide, your question and his answer will eventually make its way onto that guide. Furthermore, from time to time, he will post additional examples and other material that clarifies an article's topic, so be sure to revisit the study guides periodically.
Jeff Friesen, June 2002

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