Book Image

Mastering Concurrency Programming with Java 9 - Second Edition

By : Javier Fernández González
Book Image

Mastering Concurrency Programming with Java 9 - Second Edition

By: Javier Fernández González

Overview of this book

Concurrency programming allows several large tasks to be divided into smaller sub-tasks, which are further processed as individual tasks that run in parallel. Java 9 includes a comprehensive API with lots of ready-to-use components for easily implementing powerful concurrency applications, but with high flexibility so you can adapt these components to your needs. The book starts with a full description of the design principles of concurrent applications and explains how to parallelize a sequential algorithm. You will then be introduced to Threads and Runnables, which are an integral part of Java 9's concurrency API. You will see how to use all the components of the Java concurrency API, from the basics to the most advanced techniques, and will implement them in powerful real-world concurrency applications. The book ends with a detailed description of the tools and techniques you can use to test a concurrent Java application, along with a brief insight into other concurrency mechanisms in JVM.
Table of Contents (21 chapters)
Title Page
About the Author
About the Reviewer
Customer Feedback


The divide and conquer design technique is a very popular approach to solve different kinds of problems. You divide the original problem into smaller problems and those problems into smaller ones until you have enough simple problems to solve them directly. In version 7, the Java Concurrency API introduced a special kind of Executor optimized for this kind of problem, namely the fork/join framework. It's based on the fork operations, that allows you to create a new child task, and the join operation, that allows you to wait for the finalization of a child task before getting its results.

Using those operations, your fork/join tasks will have the following appearance:

if ( problem.size() > DEFAULT_SIZE) { 
  childTask1=new Task(); 
  childTask2=new Task(); 
  taskResults=makeResults(childTaskResults1, childTaskResults2); 
  return taskResults; 
} else {