Introduction to Big Data, Big Data Analytics and Apache Spark

1. Spark Driven Big Data
Analytics
Inosh Goonewardena
Associate Technical Lead - WSO2, Inc.

2. Agenda
● What is Big Data?
● Big Data Analytics
● Introduction to Apache Spark
● Apache Spark Components & Architecture
● Writing Spark Analytic Applications

3. What is Big Data?
● Big data is a term for data sets that are so large and complex in nature
● Constitute structured, semi-structured and unstructured data
● Big Data cannot easily be managed by traditional RDBMS or statistics
tools

4. Characteristics of Big Data - The 3Vs
http://itknowledgeexchange.techtarget.com/
writing-for-business/files/2013/02/BigData.0
01.jpg

5. Sources of Big Data
● Banking transactions
● Social Media Content
● Results of scientific experiments
● GPS trails
● Financial market data
● Mobile-phone call detail records
● Machine data captured by sensors connected to IoT devices
● ……..

6. Traditional Vs Big Data
Attribute Traditional Data Big Data
Volume Gigabytes to Terabytes Petabytes to Zettabytes
Organization Centralized Distributed
Structure Structured Structured, Semi-structured &
Unstructured
Data Model Strict schema based Flat schema
Data Relationship Complex interrelationships Almost flat with few relationships

7. Big Data Analytics
● Process of examining large data sets to uncover hidden patterns, unknown
correlations, market trends, customer preferences and other useful
business information.
● Analytical findings can lead to better more effective marketing, new
revenue opportunities, better customer service, improved operational
efficiency, competitive advantages over rival organizations and other
business benefits.
http://searchbusinessanalytics.techtarget.com/definition/big-data-analytics

8. 4 types of Analytics
● Batch
● Real-time
● Interactive
● Predictive

9. Challenges of Big Data Analytics
● Traditional RDBMS fail to handle Big Data
● Big Data cannot fit in the memory of a single computer
● Processing of Big Data in a single computer will take a lot of time
● Scaling with traditional RDBMS is expensive

10. Traditional Large-Scale Computation
● Traditionally, computation has been processor-bound
○ Relatively small amounts of data
○ Significant amount of complex processing performed on that data
● For decades, the primary push was to increase the computing power of a
single machine
○ Faster processor, more RAM

11. Hadoop
● Hadoop is an open source, Java-based programming framework that
supports the processing and storage of extremely large data sets in a
distributed computing environment
http://bigdatajury.com/wp-content/uploads/2014/
03/030114_0817_HadoopCoreC120.png

12. The Hadoop Distributed File System - HDFS
● Responsible for storing data on the cluster
● Data files are split into blocks and distributed across multiple nodes in the
cluster
● Each block is replicated multiple times
○ Default is to replicate each block three times
○ Replicas are stored on different nodes
○ This ensures both reliability and availability

13. MapReduce
● MapReduce is the system used to process data in the Hadoop cluster
● A method for distributing a task across multiple nodes
● Each node processes data stored on that node - Where possible
● Consists of two phases:
○ Map - process the input data and creates several small chunks of
data
○ Reduce - process the data that comes from the mapper and
produces a new set of output
● Scalable, Flexible, Fault-tolerant & Cost effective

14. MapReduce - Example
http://www.cs.uml.edu/~jlu1/doc/source/report/img/MapReduceExample.png

15. Limitations of MapReduce
● Slow due to replication, serialization, and disk IO
● Inefficient for:
○ Iterative algorithms (Machine Learning, Graphs & Network
Analysis)
○ Interactive Data Mining (R, Excel, Adhoc Reporting, Searching)

16. Apache Spark
● Apache Spark is a cluster computing platform designed to be fast and
general-purpose
● Extends the Hadoop MapReduce model to efficiently support more types of
computations, including interactive queries and stream processing
● Provides in-memory cluster computing that increases the processing
speed of an application
● Designed to cover a wide range of workloads that previously required
separate distributed systems, including batch applications, iterative
algorithms, interactive queries and streaming

17. Features of Spark
● Speed − Spark helps to run an application in Hadoop cluster, up to 100
times faster in memory, and 10 times faster when running on disk.
● Supports multiple languages − Spark provides built-in APIs in Java,
Scala, or Python.
● Advanced Analytics − Spark not only supports ‘Map’ and ‘reduce’. It also
supports SQL queries, Streaming data, Machine learning (ML), and Graph
algorithms.

18. Spark Stack
https://media.licdn.com/mpr/mpr/shrinknp_800_800/AAEAAQAAAAAAAAb5AAAAJDUwZGZmZWEwLWN
hZGEtNDc4NC1hOTkyLTVjMTNiYmUzNjVmNw.png

19. Components of Spark
● Apache Spark Core − Underlying general execution engine for spark
platform that all other functionality is built upon. Provides In-Memory
computing and referencing datasets in external storage systems.
● Spark SQL − Component on top of Spark Core that introduces a new data
abstraction called SchemaRDD, which provides support for structured and
semi-structured data.
● Spark Streaming − Leverages Spark Core's fast scheduling capability to
perform streaming analytics. Ingests data in mini-batches and performs
RDD transformations on those mini-batches of data.

20. Components of Spark
● MLlib − Distributed machine learning framework above Spark. Provides
multiple types of machine learning algorithms, including binary
classification, regression, clustering and collaborative filtering, as well as
supporting functionality such as model evaluation and data import.
● GraphX − Distributed graph-processing framework on top of Spark.
Provides an API for expressing graph computation that can model the
user-defined graphs by using Pregel abstraction API.

21. Why a New Programming Model?
● MapReduce simplified big data analysis.
● But users quickly wanted more:
○ More complex, multi-pass analytics (e.g. ML, graph)
○ More interactive ad-hoc queries
○ More real-time stream processing
● All 3 need faster data sharing in parallel apps

22. Data Sharing in MapReduce
● Iterative Operations on MapReduce
● Interactive Operations on MapReduce
https://www.tutorialspoint.com/apache_spark/im
ages/iterative_operations_on_mapreduce.jpg
https://www.tutorialspoint.com/apache_spark/imag
es/interactive_operations_on_mapreduce.jpg

23. Data Sharing using Spark RDD
● Iterative Operations on Spark RDD
● Interactive Operations on Spark RDD
https://www.tutorialspoint.com/apache_sp
ark/images/iterative_operations_on_spark
_rdd.jpg
https://www.tutorialspoint.com/apache_spa
rk/images/interactive_operations_on_spar
k_rdd.jpg

24. Execution Flow
http://cdn2.hubspot.net/hubfs/323094/Petr/cluster-overview.png?t=1478804099651

25. Execution Flow (contd.)
1. A standalone application starts and instantiates a SparkContext instance.
Once the SparkContext is initiated the application is called the driver.
2. The driver program ask for resources to launch executors from the cluster
manager.
3. The cluster manager launches executors.
4. The driver process runs through the user application. Depending on the
actions and transformations over RDDs task are sent to executors.
5. Executors run the tasks and save the results.
6. If any worker crashes, its tasks will be sent to different executors to be
processed again.

26. Terminology
● Application
○ User program built on Spark. Consists of a driver program and
executors on the cluster.
● Application Jar
○ A jar containing the user's Spark application and its dependencies
except Hadoop & Spark Jars
● Driver Program
○ The process where the main method of the program runs
○ Runs the user user code that creates a SparkContext, creates
RDDs, and performs actions and transformation

27. Terminology (contd.)
● SparkContext
○ Represents the connection to a Spark cluster
○ Driver programs access Spark through a SparkContext object
○ Can be used to create RDDs, accumulators and broadcast
variables on that cluster
● Cluster Manager
○ An external service to manage resources on the cluster
(standalone manager, YARN, Apache Mesos)

28. Terminology (contd.)
● Deploy Mode
○ cluster - driver inside the cluster
○ client - driver outside the cluster
● Worker node
○ Any node that can run application code in the cluster
● Executor
○ A process launched for an application on a worker node, that runs
tasks and keeps data in memory or disk storage across them.
Each application has its own executors.

29. Terminology (contd.)
● Task
○ A unit of work that will be sent to one executor
● Job
○ A parallel computation consisting of multiple tasks that gets
spawned in response to a Spark action (e.g. save, collect).
● Stage
○ Smaller set of tasks that each job is divided.
○ Sequential and depend on each other

30. Spark Pillars
Two main abstractions of Spark.
● RDD - Resilient Distributed Dataset
● DAG - Direct Acyclic Graph

31. RDD (Resilient Distributed Dataset)
● Fundamental data structure of Spark
● Immutable distributed collection of objects
● The data is partitioned across machines in the cluster that can be operated
in parallel
● Fault-tolerant
● Support two types of operations
○ Transformation
○ Action

32. RDD - Transformations
● Returns a pointer to new RDD
● lazily evaluated
● Step in a program telling Spark how to get data and what to do with it.
● Some of the most popular Spark transformations:
○ map
○ filter
○ flatMap
○ groupByKey
○ reduceByKey

33. RDD - Actions
● Return a value to the driver program after running a computation on the
dataset
● Some of the most popular Spark actions:
○ reduce
○ collect
○ count
○ take
○ saveAsTextFile

34. DAG (Direct Acyclic Graph)
A Graph that doesn’t link backwards. Defines sequence of
computations performs on data.

35. DAG (Direct Acyclic Graph)

36. DAG (Direct Acyclic Graph)
A failure happens at one of the operation

37. DAG (Direct Acyclic Graph)
Replay and reconstruct the RDD

38. DAG (Direct Acyclic Graph)

39. Writing Analytics Applications
1. SparkConf conf = new SparkConf().setMaster("local").setAppName("Word Count App");
2. JavaSparkContext sc = new JavaSparkContext(conf);
3.
4. JavaRDD<String> lines = spark.read().textFile(args[0]).javaRDD();
5.
6. JavaRDD<String> words = lines.flatMap(new FlatMapFunction<String, String>() {
7. @Override
8. public Iterator<String> call(String s) {
9. return Arrays.asList(s.split(" ")).iterator();
10. }
11. });
12.
13. JavaPairRDD<String, Integer> ones = words.mapToPair(new PairFunction<String, String, Integer>() {
14. @Override
15. public Tuple2<String, Integer> call(String s) {
16. return new Tuple2<>(s, 1);
17. }
18. });
19.
20. JavaPairRDD<String, Integer> counts = ones.reduceByKey(new Function2<Integer, Integer, Integer>() {
21. @Override
22. public Integer call(Integer i1, Integer i2) {
23. return i1 + i2;
24. }
25. });
26.
27. List<Tuple2<String, Integer>> output = counts.collect();
28 for (Tuple2<?,?> tuple : output) {
29 System.out.println(tuple._1() + ": " + tuple._2());
30. }

40. Writing Analytics Applications (contd.)
SparkConf conf = new SparkConf().setMaster("local").setAppName("Word Count App");
JavaSparkContext sc = new JavaSparkContext(conf);
JavaRDD<String> lines = spark.read().textFile(args[0]).javaRDD();
JavaRDD<String> words = lines.flatMap(new FlatMapFunction<String, String>() {
@Override
public Iterator<String> call(String s) {
return Arrays.asList(s.split(" ")).iterator();
}
});
JavaPairRDD<String, Integer> ones = words.mapToPair(new PairFunction<String, String, Integer>() {
@Override
public Tuple2<String, Integer> call(String s) {
return new Tuple2<>(s, 1);
}
});
JavaPairRDD<String, Integer> counts = ones.reduceByKey(new Function2<Integer, Integer, Integer>() {
@Override
public Integer call(Integer i1, Integer i2) {
return i1 + i2;
}
});
List<Tuple2<String, Integer>> output = counts.collect();
for (Tuple2<?,?> tuple : output) {
System.out.println(tuple._1() + ": " + tuple._2());
}
Green colored codes are not executing on the driver. Those are executing on another node.

41. Writing Analytics Applications (contd.)
SparkConf conf = new SparkConf().setMaster("local").setAppName("Word Count App");
JavaSparkContext sc = new JavaSparkContext(conf);
JavaRDD<String> lines = spark.read().textFile(args[0]).javaRDD();
JavaRDD<String> words =lines.flatMap(new FlatMapFunction<String, String>() {
@Override
public Iterator<String> call(String s) {
return Arrays.asList(s.split(" ")).iterator();
}
});
JavaPairRDD<String, Integer> ones =words.mapToPair(new PairFunction<String, String, Integer>() {
@Override
public Tuple2<String, Integer> call(String s) {
return new Tuple2<>(s, 1);
}
});
JavaPairRDD<String, Integer> counts =ones.reduceByKey(new Function2<Integer, Integer, Integer>() {
@Override
public Integer call(Integer i1, Integer i2) {
return i1 + i2;
}
});
List<Tuple2<String, Integer>> output =counts.collect();
for (Tuple2<?,?> tuple : output) {
System.out.println(tuple._1() + ": " + tuple._2());
}
Blue colored codes are transformations. Red colored code is an action. Green colored code is stuffs
that happens locally (not Spark related things)

42. Writing Analytics Applications (Java 8)
SparkConf conf = new SparkConf().setMaster("local").setAppName("Word Count App");
JavaSparkContext sc = new JavaSparkContext(conf);
// Load the input data, which is a text file read from the command line
JavaRDD<String> lines = sc.textFile(filename);
JavaRDD<String> words = lines.flatMap(line -> Arrays.asList(line.split(" ")).iterator());
JavaPairRDD<String, Integer> ones = words.mapToPair(w -> new Tuple2<>(w, 1));
JavaPairRDD<String, Integer> counts = ones.reduceByKey((i1, i2) -> i1 + i2);
List<Tuple2<String, Integer>> output = counts.collect();
for (Tuple2<?,?> tuple : output) {
System.out.println(tuple._1() + ": " + tuple._2());
}

43. Demo

44. Questions?