Introduction to Apache Spark

Overview

Teaching: 0 min
Exercises: 0 min
Questions
  • What is Spark?

  • How programming is done in Spark?

Objectives
  • Understand the general concept of MapReduce programming model

1. What is Spark?

  • A unified compute engine and a set of libraries for parallel data processing on computer clusters.
  • Click the JupyterHub link

Spark

2. Design philosophy

  • Unified: Spark supports a wide range of data analytic tasks over the same computing engine and a consistent set of APIs.
  • Computing engine: Spark handles loading data from storage systems and perform computation on the data (in memory) rather than on permanent storage. To adhere to the data locality principle, Spark relies on APIs to provide a transparent common interface with different storage systems for all applications.
  • Libraries: Via its APIs, Spark supports a wide array of internal and external libraries for complex data analytic tasks.

3. A brief history of Spark

  • Research project at UC Berkeley AMP Lab in 2009 to address drawbacks of Hadoop MapReduce.
  • Paper published in 2010: Spark: Cluster Computing with Working Sets
  • Source code is contributed to Apache in 2013. The project had more than 100 contributors from more than 30 organizations outside UC Berkeley.
  • Version 1.0 was released in 2014.
  • Currently, Spark is being used extensively in academic and industry (NASA, CERN, Uber, Netflix …).

4. map and reduce

  • What is map? A function/procedure that is applied to every individual elements of a collection/list/array/…
int square(x) { return x*x;}
map square [1,2,3,4] -> [1,4,9,16]
  • What is “reduce”? A function/procedure that performs an operation on a list. This operation will “fold/reduce” this list into a single value (or a smaller subset).
reduce ([1,2,3,4]) using sum -> 10
reduce ([1,2,3,4]) using multiply -> 24

5. MapReduce programming paradigm

  • Programmers implement:
    • Map function: Take in the input data and return a key,value pair.
    • Reduce function: Receive the key,value pairs from the mapper and provide a final output as a reduction operation on the pairs.
  • MapReduce Framework handles everything else.
  • Spark implements a MapReduce framework.

6. WordCount: the Hello, World! of Big Data

  • Count how many unique words there are in a file/multiple files.
  • Standard parallel programming approach:
    • Count number of files
    • Set number of processes
    • Possibly setting up dynamic workload assignment
    • A lot of data transfer
    • Significant coding effort

MapReduce workflow

Spark

MapReduce framework

Spark

Key Points

  • Spark provides a framework to support big data analytics via MapReduce programming paradigm, unified compute engine, and supporting data processing and analytics libraries.