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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Chapter 7. Software Transactional Memory


"Everybody who learns concurrency and thinks they understand it, ends up finding mysterious races they thought weren't possible, and discovers that they didn't actually understand it yet after all."

 --Herb Sutter

While investigating the fundamental primitives of concurrency in Chapter 2, Concurrency on the JVM and the Java Memory Model, we recognized the need for protecting parts of the program from shared access. We saw that a basic way of achieving this isolation is the synchronized statement, which uses intrinsic object locks to ensure that at most a single thread executes a specific part of the program at the same time. The disadvantage of using locks is that they can easily cause deadlocks, a situation in which the program cannot progress.

In this chapter, we will introduce Software Transactional Memory (STM), a concurrency control mechanism for controlling access to shared memory, which greatly reduces the risk of deadlocks and races. An STM...