Book Image

Learning Concurrent Programming in Scala - Second Edition

By : Aleksandar Prokopec
Book Image

Learning Concurrent Programming in Scala - Second Edition

By: Aleksandar Prokopec

Overview of this book

Scala is a modern, multiparadigm programming language designed to express common programming patterns in a concise, elegant, and type-safe way. Scala smoothly integrates the features of object-oriented and functional languages. In this second edition, you will find updated coverage of the Scala 2.12 platform. The Scala 2.12 series targets Java 8 and requires it for execution. The book starts by introducing you to the foundations of concurrent programming on the JVM, outlining the basics of the Java Memory Model, and then shows some of the classic building blocks of concurrency, such as the atomic variables, thread pools, and concurrent data structures, along with the caveats of traditional concurrency. The book then walks you through different high-level concurrency abstractions, each tailored toward a specific class of programming tasks, while touching on the latest advancements of async programming capabilities of Scala. It also covers some useful patterns and idioms to use with the techniques described. Finally, the book presents an overview of when to use which concurrency library and demonstrates how they all work together, and then presents new exciting approaches to building concurrent and distributed systems. Who this book is written for If you are a Scala programmer with no prior knowledge of concurrent programming, or seeking to broaden your existing knowledge about concurrency, this book is for you. Basic knowledge of the Scala programming language will be helpful.
Table of Contents (19 chapters)
Learning Concurrent Programming in Scala - Second Edition
About the Author
About the Reviewers
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Reactor lifecycle

Every reactor goes through a certain set of stages during its lifetime, which are jointly called a reactor lifecycle. When the reactor enters a specific stage, it emits a lifecycle event. These lifecycle events are dispatched on a special daemon event stream called sysEvents. Every reactor is created with this special event stream.

The reactor lifecycle can be summarized as follows:

  • After calling the spawn method, the reactor is scheduled for execution. Its constructor is started asynchronously, and immediately after that, a ReactorStarted event is dispatched.

  • Then, whenever the reactor gets execution time, the ReactorScheduled event gets dispatched. After that, events get dispatched on normal event streams.

  • When the scheduling system decides to pre-empt the reactor, the ReactorPreempted event is dispatched. This scheduling cycle can be repeated any number of times.

  • Eventually, the reactor terminates, either by normal execution or exceptionally. If a user code exception terminates...