Book Image

Mastering Apache Spark 2.x - Second Edition

Book Image

Mastering Apache Spark 2.x - Second Edition

Overview of this book

Apache Spark is an in-memory, cluster-based Big Data processing system that provides a wide range of functionalities such as graph processing, machine learning, stream processing, and more. This book will take your knowledge of Apache Spark to the next level by teaching you how to expand Spark’s functionality and build your data flows and machine/deep learning programs on top of the platform. The book starts with a quick overview of the Apache Spark ecosystem, and introduces you to the new features and capabilities in Apache Spark 2.x. You will then work with the different modules in Apache Spark such as interactive querying with Spark SQL, using DataFrames and DataSets effectively, streaming analytics with Spark Streaming, and performing machine learning and deep learning on Spark using MLlib and external tools such as H20 and Deeplearning4j. The book also contains chapters on efficient graph processing, memory management and using Apache Spark on the cloud. By the end of this book, you will have all the necessary information to master Apache Spark, and use it efficiently for Big Data processing and analytics.
Table of Contents (21 chapters)
Title Page
Credits
About the Author
About the Reviewer
www.PacktPub.com
Customer Feedback
Preface
10
Deep Learning on Apache Spark with DeepLearning4j and H2O

Code generation


Finally, things can be improved even more, since Apache Spark runs on the Java Virtual Machine (JVM), which allows byte code to be created and modified during runtime. Let's consider an addition of values a and b, resulting in the expression a+b. Normally, this expression had to be interpreted by the JVM for each row of the Dataset. It would be nice if we could generate the JVM ByteCode for this expression on the fly. This is possible, and Catalyst makes use of a very cool Scala feature called Quasiquotes, which basically allows an arbitrary string containing Scala code to be compiled into ByteCode on the fly, if it starts with q. So for example, q"row.get($a)+row.get($b)" will tell the Scala compiler to use this String to generate further JVM byte code. This way, less code has to be interpreted, which speeds things up.

Practical examples

In order to facilitate understanding of these components, we'll introduce some practical examples using Scala code. Consider data about clients...