Book Image

Apache Spark 2.x Cookbook

By : Rishi Yadav
Book Image

Apache Spark 2.x Cookbook

By: Rishi Yadav

Overview of this book

While Apache Spark 1.x gained a lot of traction and adoption in the early years, Spark 2.x delivers notable improvements in the areas of API, schema awareness, Performance, Structured Streaming, and simplifying building blocks to build better, faster, smarter, and more accessible big data applications. This book uncovers all these features in the form of structured recipes to analyze and mature large and complex sets of data. Starting with installing and configuring Apache Spark with various cluster managers, you will learn to set up development environments. Further on, you will be introduced to working with RDDs, DataFrames and Datasets to operate on schema aware data, and real-time streaming with various sources such as Twitter Stream and Apache Kafka. You will also work through recipes on machine learning, including supervised learning, unsupervised learning & recommendation engines in Spark. Last but not least, the final few chapters delve deeper into the concepts of graph processing using GraphX, securing your implementations, cluster optimization, and troubleshooting.
Table of Contents (19 chapters)
Title Page
Credits
About the Author
About the Reviewer
www.PacktPub.com
Customer Feedback
Preface

Leveraging speculation


Like MapReduce, Spark uses speculation to spawn additional tasks if it suspects a task is running on a straggler node. A good use case would be to think of a situation when 95 percent or 99 percent of your job finishes really fast and then gets stuck (we have all been there).

How to do it...

There are a few settings you can use to control speculation. The examples are provided only to show how to change values. Mostly, just turning on speculation is good enough:

  1. Setting spark.speculation (the default is false):
$ spark-shell -conf spark.speculation=true
  1. Setting spark.speculation.interval (the default is 100 milliseconds) (denotes the rate at which Spark examines tasks to see whether speculation is needed): 
$ spark-shell -conf spark.speculation.interval=200
  1. Setting spark.speculation.multiplier (the default is 1.5) (denotes how many times a task has to be slower than median to be a candidate for speculation):
$ spark-shell -conf spark.speculation.multiplier=1.5
  1. Setting spark...