Sparkler - Spark Crawler

Nov 15th
2016
@ Apache Big Data EU 2016, Seville, Spain
Thamme GowdaKaranjeet Singh
SPARKLER
Information Retrieval
and Data Science
Chris Mattmann

ABOUT: USC INFORMATION RETRIEVAL
AND DATA SCIENCE GROUP
● Established in August 2012 at the University of Southern California (USC)
● Dr. Chris Mattmann, Director of IRDS and our Advisor
● Funding from NSF, DARPA, NASA, DHS, private industry and other agencies
- in collaboration with NASA JPL
● 3 Postdocs, and 30+ Masters and PhD students, 20+ JPLers past 7 years
● Recent topical research in the DARPA XDATA/MEMEX program
and Data Science
Email : irds-L@mymaillists.usc.edu
Website : http://irds.usc.edu/
GitHub : https://github.com/USCDataScience/

ABOUT: US
Karanjeet Singh
Graduate Student at the University of Southern California, USA
Research Interest: Information Retrieval & Natural Language Processing
Research Affiliate at NASA Jet Propulsion Laboratory
Committer and PMC member of Apache Nutch
and Data Science
Thamme Gowda
Graduate Student at the University of Southern California, USA
Research Intern at NASA Jet Propulsion Laboratory, Co Founder at Datoin
Research Interest: NLP, Machine Learning and Information Retrieval
Committer and PMC member of Apache Nutch, Tika, and Joshua (Incubating)
Dr. Chris Mattmann
Director & Vice Chairman, Apache Software Foundation
Research Interest: Data Science, Open Source, Information Retrieval & NLP
Committer and PMC member of Apache Nutch, Tika, (former) Lucene, OODT, Incubator

OVERVIEW
● About Sparkler
● Motivations for building Sparkler
● Quick intro to Apache Spark
● Sparkler technology stack, internals
● Features of Sparkler
● Comparison with Nutch
● Going forward
and Data Science

ABOUT: SPARKLER
● New Open Source Web Crawler
○ A bot program that can fetch resources from the web
● Name: Spark Crawler
● Inspired by Apache Nutch
● Like Nutch: Distributed crawler that can scale horizontally
● Unlike Nutch: Runs on top of Apache Spark
● Easy to deploy and easy to use
and Data Science

and Data Science
MOTIVATION #1
● Challenges in DARPA MEMEX
○ Intro: MEMEX System has crawlers to fetch deep and
dark web data for assisting law keeping agencies
○ Crawls are kind of blackbox, we wanted real-time
progress reports
● Dr. Chris Mattmann was considering an upgrade since 3
years
● Technology upgrade needed

and Data Science
https://twitter.com/cutting/status/796566255830503424
Modern Hadoop cluster has no Hadoop (Map-Reduce) left in it!
WHY A NEW CRAWLER?

and Data Science
MOTIVATION #2
● Challenges at DATOIN
○ Intro: Datoin is a distributed text analytics platform
○ Late 2014 - migrated the infrastructure from Hadoop
Map Reduce to Apache Spark
○ But the crawler component (powered by Apache Nutch)
was left behind
● Met Dr. Chris Mattmann at USC in Web Search Engines
class
○ Enquired about his thoughts for running Nutch on Spark
○ Agreed to work on it.

● High performance & Fault tolerance
● Real time crawl analysis
● Easy to customize
Is the food ready?
How is it going?
I want less salt.
and Data Science
KEY FEATURES

APACHE SPARK: OVERVIEW
● Introduction
● Resilient Distributed Dataset (RDD)
● Driver, Workers & Executors
and Data Science

APACHE SPARK: INTRODUCTION
● Fast and general engine for large scale data processing
● Started at UC Berkeley in 2009
● The most popular distributed computing framework
● Provides high level APIs in Scala, Java, Python, R
● Integration with Hadoop and its ecosystem
● Open sourced in 2010 under Apache v2.0 license
● Mattmann helped to bring Spark to Apache under
DARPA XDATA effort
and Data Science

Resilient Distributed Dataset (RDD)
● A basic abstraction in Spark
● Immutable, Partitioned collection of elements operated in parallel
● Data in persistent store (HDFS, Cassandra) or in cache (memory, disk)
● Partitions are recomputed on failure or cache eviction
● Two classes of operations
○ Transformations
○ Actions
● Custom RDDs can also be
implemented - we have one!
and Data Science

and Data Science
Driver, Workers & Executors
* Photo credit - spark.apache.org

SPARKLER: TECH STACK
● Batch crawling (similar to Apache Nutch)
● Apache Solr as crawl database
● Multi module Maven project with OSGi bundles
● Stream crawled content through Apache Kafka
● Parses everything using Apache Tika
● Crawl visualization - Banana
and Data Science

SPARKLER: INTERNALS & WORKFLOW
and Data Science

SPARKLER: FEATURES
and Data Science

● Crawldb needed indexing
○ For real time analytics
○ For instant visualizations
● This is internal data structure of sparkler
○ Exposed over REST API
○ Used by Sparkler-ui, the web application
● We chose Apache Solr
● Standalone Solr Server or Solr Cloud?
● Glued the crawldb and spark using CrawldbRDD
SPARKLER #1: Lucene/Solr powered Crawldb
and Data Science

SPARKLER #2: Partitioning by host
and Data Science
● Politeness
* Doesn’t hit same server too many times in distributed mode
● First version
○ Group by: Host name
○ Sort by: depth, score
● Customization is easy
○ Write your own Solr query
○ Take advantage of boosting to alter the ranking
● Partitions the dataset based on the above criteria
● Lazy evaluations and delay between the requests
■ Performs parsing instead of waiting
■ Inserts delay only when it is necessary

SPARKLER #3: OSGI Plugins
and Data Science
● Plugins Interfaces are inspired by Nutch
● Plugins are developed as per Open Service Gateway
Interface (OSGI)
● We chose Apache Felix implementation of OSGI
● Migrated a plugin from Nutch
○ Regex URL Filter Plugin → The most used plugin in
Nutch
● Added JavaScript plugin (described in the next slide)
● //TODO: Migrate more plugins from Nutch
○ Mavenize nutch [NUTCH-2293]

SPARKLER #4: JavaScript Rendering
and Data Science
● Java Script Execution* has first class support
● Distributable on Spark Cluster without pain
○ Pure JVM based JavaScript engine
● This is an implementation of FetchFunction
● FetchFunction
○ Stream<URL> → Stream<Content>
○ Note: URLS are grouped by host
○ It preserves cookies and reuses sessions for each iteration
Thanks to: Madhav Sharan
Member of USC IRDS* JBrowserDriver by MachinePublishers

SPARKLER #5: Output in Kafka Streams
and Data Science
● Crawler is sometimes input for the applications that does
deeper analysis
○ Can’t fit all those deeper analysis into crawler
● Integrating to such applications made easy via Queues
● We chose Apache Kafka
○ Suits our need
■ Distributable, Scalable, Fault Tolerant
● FIXME: Larger messages such as Videos
● This is optional, default output on Shared File System
(such as HDFS), compatible with Nutch
*
Thanks to: Rahul Palamuttam
MS CS @ Stanford University; Intern @ NASA JPL)

SPARKLER #6: Tika, the universal parser
and Data Science
● Apache Tika
○ Is a toolkit of parsers
○ Detects and extracts metadata, text, and URLS
○ Over a thousand different file types
● Main application is to discover outgoing links
● The default Implementation for our ParseFunction

SPARKLER #7: Visual Analytics
and Data Science
● Charts and Graphs provides nice summary of crawl job
● Real time analytics
● Example:
○ Distribution of URLS across hosts/domains
○ Temporal activities
○ Status reports
● Customizable in real time
● Using Banana Dashboard from Lucidworks
● Sparkler has a sub component named sparkler-ui
* Thanks to : Manish Dwibedy
MS CS University of Southern California

SPARKLER #Next: what’s coming?
and Data Science
● Interactive UI
● More plugins
● Scoring Crawled Pages
● Focussed Crawling
● Crawl Graph Analysis
● Domain Discovery (another research challenge)
● Other useful plugins from Nutch
● Detailed documentation and tutorials on wiki

Nutch Configuration
Version : 1.12
topN : 50,000
Fetcher Thread : 1
Hadoop Configuration
Version : 2.6.0-cdh5.8.2
Slaves : 2
Memory : 8G (Map), 16G (Reduce)
22 Mappers, 11 reducers
HOW FAST IT RUNS - Comparison with Nutch
and Data Science
Crawl Iterations : 5
Fetch Delay : 1 sec
Sparkler Configuration
Version : 0.1-SNAPSHOT
topGroups : 252
topN : 1000
Spark Configuration
Version : 1.6.1 with Scala v2.11
Slaves : 2
22 Worker Instances with 210G memory

and Data Science
DIVERSIFIED - Comparison with Nutch

and Data Science
Sparkler Dashboard

and Data Science
SPARKLER IS COMING TO APACHE
proposal later this week!
Look for

● Get involved with our journey of Incubator
● Get started: Checkout README and wiki at
https://github.com/USCDataScience/sparkler
and Data Science
Questions?
THANK YOU

Sparkler - Spark Crawler

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