Preface

When you work with a computer, you can do several things at once. You can listen to music while you edit a document in a word processor and read your e-mails. This can be done because your operating system allows the concurrency of tasks. Concurrent programming is about the elements and mechanisms a platform offers to have multiple tasks or programs running at once and communicating with each other, to exchange data or to synchronize with each other. Java is a concurrent platform, and it offers a lot of classes to execute concurrent tasks inside a Java program. With each version, Java increases the functionalities offered to programmers to facilitate the development of concurrent programs. This book covers the most important and useful mechanisms included in version 9 of the Java concurrency API, so you will be able to use them directly in your applications. The mechanisms are as follows:

• Basic thread management
• Thread synchronization mechanisms
• Thread creation and management delegation with executors
• Fork/Join framework to enhance the performance of your application
• Parallel streams to process big sets of data in a parallel way, including the new Java 9 reactive streams
• Data structures for concurrent programs
• Adapting the default behavior of some concurrency classes to your needs
• Testing Java concurrency applications

What this book covers

Chapter 1, Thread Management, teaches you how to make basic operations with threads. The creation, execution, and status management of threads are explained through basic examples.

Chapter 2, Basic Thread Synchronization, covers how to use low-level Java mechanisms to synchronize code. Locks and the synchronized keyword are explained in detail.

Chapter 3, Thread Synchronization Utilities, teaches how to use the high-level utilities of Java to manage the synchronization between threads in Java. It includes an explanation of how to use the Phaser class to synchronize tasks divided into phases.

Chapter 4, Thread Executors, explores the delegation of thread management to executors. They allow running, managing, and getting the results of concurrent tasks.

Chapter 5, Fork/Join Framework, covers the use of the Fork/Join framework. It’s a special kind of executor oriented to execute tasks that will be divided into smaller ones using the divide and conquer technique.

Chapter 6, Parallel and Reactive Streams, teaches you how to create streams and use all its intermediate and terminal operations to process big collections of data in a parallel and functional way. Streams were introduced in Java 8. Java 9 has included some new interfaces to implement reactive streams.

Chapter 7, Concurrent Collections, explains how to use some concurrent data structures provided by the Java language. These data structures must be used in concurrent programs to avoid the use of synchronized blocks of code in their implementation.

Chapter 8, Customizing Concurrency Classes, teaches you how to adapt some of the most useful classes of the Java concurrency API to your needs.

Chapter 9, Testing Concurrent Applications, covers how to obtain information about the status of some of the most useful structures of the Java 7 concurrency API. You will also learn how to use some free tools to debug concurrent applications, such as the Eclipse, NetBeans IDE, or FindBugs applications to detect possible bugs in your applications.

Chapter 10, Additional Information, explores the notions of synchronization, the executor, the Fork/Join framework, concurrent data structures, and the monitoring of concurrent objects, which were not included in the respective chapters.

Chapter 11, Concurrent Programming Design, provides some tips that every programmer should consider when they develop a concurrent application.

What you need for this book

To follow this book, you need some basic knowledge of the Java programming language. You should know how to use an IDE, such as Eclipse or NetBeans, but this is not a necessary prerequisite.

Who this book is for

If you are a Java developer interested in enhancing your knowledge of concurrent programming and multithreading further, as well as discovering the new concurrency features of Java 8 and Java 9, then the Java 9 Concurrency Cookbook is for you. You should already be comfortable with general Java development practices, and a basic grasp of threads would be an advantage.

Sections

In this book, you will find several headings that appear frequently (Getting ready, How to do it, How it works, There's more, and See also).

To give clear instructions on how to complete a recipe, we use these sections as follows:

Getting ready

This section tells you what to expect in the recipe, and describes how to set up any software or any preliminary settings required for the recipe.

How to do it…

This section contains the steps required to follow the recipe.

How it works…

This section usually consists of a detailed explanation of what happened in the previous section.

There's more…

This section consists of additional information about the recipe in order to make the reader more knowledgeable about the recipe.

See also

This section provides helpful links to other useful information for the recipe.

Conventions

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task.start(); 

New terms and important words are shown in bold. Words that you see on the screen, for example, in menus or dialog boxes, appear in the text like this: "Create a new project by clicking on the New Project option under the File menu"

Note

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Note

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