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
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Composing transactions

When used correctly, transactional memory is a powerful tool for building concurrent applications that modify shared data. Nevertheless, no technology is a silver bullet, and neither is STM. In this section, we will study how to compose transactions in larger programs and learn how transactional memory interacts with other features of Scala. We investigate some of the caveats of STM, and go beyond transactional references and the atomic statement blocks to show how to use STM more effectively.

The interaction between transactions and side effects

Previously, we learned that an STM may roll back and retry a transaction. An attentive reader might notice that retrying a transaction means re-executing its side effects. Here, the side effects are arbitrary reads and writes to regular object fields and variables.

Sometimes, side effects are not a problem. Transactional references cannot be modified outside a transaction, and inside a transaction their modifications are aborted...