Book Image

Akka Cookbook

By : Vivek Mishra, Héctor Veiga Ortiz
Book Image

Akka Cookbook

By: Vivek Mishra, Héctor Veiga Ortiz

Overview of this book

Akka is an open source toolkit that simplifies the construction of distributed and concurrent applications on the JVM. This book will teach you how to develop reactive applications in Scala using the Akka framework. This book will show you how to build concurrent, scalable, and reactive applications in Akka. You will see how to create high performance applications, extend applications, build microservices with Lagom, and more. We will explore Akka's actor model and show you how to incorporate concurrency into your applications. The book puts a special emphasis on performance improvement and how to make an application available for users. We also make a special mention of message routing and construction. By the end of this book, you will be able to create a high-performing Scala application using the Akka framework.
Table of Contents (18 chapters)
Title Page
About the Authors
About the Reviewer
Customer Feedback

The Master Slave work pulling pattern

We have seen how Akka actors behave: each actor is able to process one message at a time and the rest of the messages get enqueued into the mailbox. If the code inside a given actor takes time, it's likely that the messages sent to that actor will pile up in the mailbox. If the mailbox type is unbounded, this could lead to an out-of-memory error. If it is bounded, it will probably drop messages when it reaches the maximum size. 

To have better control over this kind of scenario, we can use the Master Slave work pulling pattern. This pattern lets a master actor control how many slaves can do work and distribute it among them. It only pushes work tasks to them when they are ready. Therefore, it is possible to manage the behavior of your system when all slaves are busy doing work. For example, we could slow the consuming of data in case we are receiving messages from a message broker. This pattern is a primitive kind of back pressure mechanism. For a more...