Big Data Analytics Beyond Hadoop

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贡献于2014-05-27

字数:0 关键词: Hadoop 分布式/云计算/大数据

Big Data Analytics Beyond Hadoop This page intentionally left blank Big Data Analytics Beyond Hadoop Real-Time Applications with Storm, Spark, and More Hadoop Alternatives Vijay Srinivas Agneeswaran, Ph.D. Associate Publisher: Amy Neidlinger Executive Editor: Jeanne Glasser Levine Operations Specialist: Jodi Kemper Cover Designer: Chuti Prasertsith Managing Editor: Kristy Hart Senior Project Editor: Lori Lyons Copy Editor: Cheri Clark Proofreader: Anne Goebel Senior Indexer: Cheryl Lenser Compositor: Nonie Ratcliff Manufacturing Buyer: Dan Uhrig © 2014 by Vijay Srinivas Agneeswaran Pearson Education, Inc. Upper Saddle River, New Jersey 07458 For information about buying this title in bulk quantities, or for special sales opportuni- ties (which may include electronic versions; custom cover designs; and content particular to your business, training goals, marketing focus, or branding interests), please contact our corporate sales department at corpsales@pearsoned.com or (800) 382-3419. For government sales inquiries, please contact governmentsales@pearsoned.com . For questions about sales outside the U.S., please contact international@pearsoned.com . Company and product names mentioned herein are the trademarks or registered trade- marks of their respective owners. Apache Hadoop is a trademark of the Apache Software Foundation. All rights reserved. No part of this book may be reproduced, in any form or by any means, without permission in writing from the publisher. Printed in the United States of America First Printing April 2014 ISBN-10: 0-13-383794-7 ISBN-13: 978-0-13-383794-0 Pearson Education LTD. Pearson Education Australia PTY, Limited. Pearson Education Singapore, Pte. Ltd. Pearson Education Asia, Ltd. Pearson Education Canada, Ltd. Pearson Educación de Mexico, S.A. de C.V. Pearson Education—Japan Pearson Education Malaysia, Pte. Ltd. Library of Congress Control Number: 2014933363 This book is dedicated at the feet of Lord Nataraja. This page intentionally left blank Contents Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix About the Author . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xvii Chapter 1 Introduction: Why Look Beyond Hadoop Map-Reduce? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1 Hadoop Suitability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Big Data Analytics: Evolution of Machine Learning Realizations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Closing Remarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Chapter 2 What Is the Berkeley Data Analytics Stack (BDAS)? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21 Motivation for BDAS . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21 BDAS Design and Architecture. . . . . . . . . . . . . . . . . . . . . 26 Spark: Paradigm for Efficient Data Processing on a Cluster . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 Shark: SQL Interface over a Distributed System . . . . . . .42 Mesos: Cluster Scheduling and Management System . . . 46 Closing Remarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 Chapter 3 Realizing Machine Learning Algorithms with Spark. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .61 Basics of Machine Learning . . . . . . . . . . . . . . . . . . . . . . . . 61 Logistic Regression: An Overview . . . . . . . . . . . . . . . . . . .67 Logistic Regression Algorithm in Spark. . . . . . . . . . . . . . . 70 Support Vector Machine (SVM) . . . . . . . . . . . . . . . . . . . . 74 PMML Support in Spark . . . . . . . . . . . . . . . . . . . . . . . . . .79 Machine Learning on Spark with MLbase . . . . . . . . . . . . 90 References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 viii BIG DATA ANALYTICS BEYOND HADOOP Chapter 4 Realizing Machine Learning Algorithms in Real Time. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .93 Introduction to Storm. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93 Design Patterns in Storm . . . . . . . . . . . . . . . . . . . . . . . . . 102 Implementing Logistic Regression Algorithm in Storm. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107 Implementing Support Vector Machine Algorithm in Storm. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110 Naive Bayes PMML Support in Storm . . . . . . . . . . . . . .113 Real-Time Analytic Applications . . . . . . . . . . . . . . . . . . .116 Spark Streaming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .124 References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126 Chapter 5 Graph Processing Paradigms. . . . . . . . . . . . . . . . . . . . .129 Pregel: Graph-Processing Framework Based on BSP. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130 Open Source Pregel Implementations. . . . . . . . . . . . . . . 134 GraphLab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138 References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156 Chapter 6 Conclusions: Big Data Analytics Beyond Hadoop Map-Reduce. . . . . . . . . . . . . . . . . . . . . . . . . . .161 Overview of Hadoop YARN . . . . . . . . . . . . . . . . . . . . . . . 162 Other Frameworks over YARN . . . . . . . . . . . . . . . . . . . .165 What Does the Future Hold for Big Data Analytics? . . . 166 References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169 Appendix A Code Sketches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .171 Code for Naive Bayes PMML Scoring in Spark . . . . . . .171 Code for Linear Regression PMML Support in Spark . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .182 Page Rank in GraphLab . . . . . . . . . . . . . . . . . . . . . . . . . . 186 SGD in GraphLab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191 Index. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209 Foreword One point that I attempt to impress upon people learning about Big Data is that while Apache Hadoop is quite useful, and most certainly quite successful as a technology, the underlying premise has become dated. Consider the timeline: MapReduce implementation by Google came from work that dates back to 2002, published in 2004. Yahoo! began to sponsor the Hadoop project in 2006. MR is based on the economics of data centers from a decade ago. Since that time, so much has changed: multi-core processors, large memory spaces, 10G networks, SSDs, and such, have become cost-effective in the years since. These dramatically alter the trade-offs for building fault-tolerant distributed systems at scale on commodity hardware. Moreover, even our notions of what can be accomplished with data at scale have also changed. Successes of firms such as Amazon, eBay, and Google raised the bar, bringing subsequent business leaders to rethink, “What can be performed with data?” For example, would there have been a use case for large-scale graph queries to optimize business for a large book publisher a decade ago? No, not particularly. It is unlikely that senior executives in publishing would have bothered to read such an outlandish engineering proposal. The marketing of this book itself will be based on a large-scale, open source, graph query engine described in subsequent chapters. Similarly, the ad-tech and social network use cases that drove the development and adoption of Apache Hadoop are now dwarfed by data rates from the Industrial Internet, the so-called “Internet of Things” (IoT)—in some cases, by several orders of magnitude. The shape of the underlying systems has changed so much since MR at scale on commodity hardware was first formulated. The shape of our business needs and expectations has also changed x BIG DATA ANALYTICS BEYOND HADOOP dramatically because many people have begun to realize what is possible. Furthermore, the applications of math for data at scale are quite different than what would have been conceived a decade ago. Popular programming languages have evolved along with that to support better software engineering practices for parallel processing. Dr. Agneeswaran considers these topics and more in a careful, methodical approach, presenting a thorough view of the contemporary Big Data environment and beyond. He brings the read to look past the preceding decade’s fixation on batch analytics via MapReduce. The chapters include historical context, which is crucial for key understandings, and they provide clear business use cases that are crucial for applying this technology to what matters. The arguments provide analyses, per use case, to indicate why Hadoop does not particularly fit—thoroughly researched with citations, for an excellent survey of available open source technologies, along with a review of the published literature for that which is not open source. This book explores the best practices and available technologies for data access patterns that are required in business today beyond Hadoop: iterative, streaming, graphs, and more. For example, in some businesses revenue loss can be measured in milliseconds, such that the notion of a “batch window” has no bearing. Real-time analytics are the only conceivable solutions in those cases. Open source frameworks such as Apache Spark, Storm, Titan, GraphLab, and Apache Mesos address these needs. Dr. Agneeswaran guides the reader through the architectures and computational models for each, exploring common design patterns. He includes both the scope of business implications as well as the details of specific implementations and code examples. Along with these frameworks, this book also presents a compelling case for the open standard PMML, allowing predictive models to be migrated consistently between different platforms and environments. It also leads up to YARN and the next generation beyond MapReduce. FOREWORD xi This is precisely the focus that is needed in industry today—given that Hadoop was based on IT economics from 2002, while the newer frameworks address contemporary industry use cases much more closely. Moreover, this book provides both an expert guide and a warm welcome into a world of possibilities enabled by Big Data analytics. Paco Nathan Author of Enterprise Data Workflows with Cascading; Advisor at Zettacap and Amplify Partners This page intentionally left blank ACKNOWLEDGMENTS xiii Acknowledgments First and foremost, I would like to sincerely thank Vineet Tyagi, AVP and head of Innovation Labs at Impetus. Vineet has been instrumental and enabled me to take up book writing. He has been kind enough to give me three hours of official time over six to seven months—this has been crucial in helping me write the book. Any such scholarly activity needs consistent, dedicated time—it would have been doubly hard if I had to write the book in addition to my day job. Vineet just made it so that at least a portion of book writing is part of my job! I would also like to express my gratitude to Pankaj Mittal, CTO and SVP, Impetus, for extending his whole-hearted support for research and development (R&D) and enabling folks like me to work on R&D full time. Kudos to him, that Impetus is able to have an R&D team without billability and revenue pressures. This has really freed me up and helped me to focus on R&D. Writing a book while work- ing in the IT industry can be an arduous job. Thanks to Pankaj for enabling this and similar activities. Praveen Kankariya, CEO of Impetus, has also been a source of inspiration and guidance. Thanks, Praveen, for the support! I also wish to thank Dr. Nitin Agarwal, AVP and head, Data Sci- ences Practice group at Impetus. Nitin has helped to shape some of my thinking especially after our discussions on realization/implemen- tation of machine learning algorithms. He has been a person I look up to and an inspiration to excel in life. Nitin, being a former professor at the Indian Institute of Management (IIM) Indore, exemplifies my high opinion of academicians in general! This book would not have taken shape without Pranay Tonpay, Senior Architect at Impetus, who leads the real-time analytics stream in my R&D team. He has been instrumental in helping realize the xiv BIG DATA ANALYTICS BEYOND HADOOP ideas in this book including some of the machine learning algorithms over Spark and Storm. He has been my go-to man. Special thanks to Pranay. Jayati Tiwari, Senior Software Engineer, Impetus, has also con- tributed some of the machine learning algorithms over Spark and Storm. She has a very good understanding of Storm—in fact, she is considered the Storm expert in the organization. She has also devel- oped an inclination to understand machine learning and Spark. It has been a pleasure having her on the team. Thanks, Jayati! Sai Sagar, Software Engineer at Impetus, has also been instru- mental in implementing machine learning algorithms over GraphLab. Thanks, Sagar, nice to have you on the team! Ankit Sharma, formerly data scientist at Impetus, now a Research Engineer at Snapdeal, wrote a small section on Logistic Regression (LR) which was the basis of the LR explained in Chapter 3 of this book. Thanks, Ankit, for that and some of our nice discussions on machine learning! I would also like to thank editor Jeanne Levine, Lori Lyons and other staff of Pearson, who have been helpful in getting the book into its final shape from the crude form I gave them! Thanks also to Pear- son, the publishing house who has brought out this book. I would like to thank Gurvinder Arora, our technical writer, for having reviewed the various chapters of the book. I would like to take this opportunity to thank my doctoral guide Professor D. Janakiram of the Indian Institute of Technology (IIT) Madras, who has inspired me to take up a research career in my for- mative years. I owe a lot to him—he has shaped my technical thinking, moral values, and been a source of inspiration throughout my profes- sional life. In fact, the very idea of writing a book was inspired by his recently released book Building Large Scale Software Systems with Tata McGraw-Hill publishers. Not only Prof. DJ, I also wish to thank all my teachers, starting from my high school teachers at Sankara, ACKNOWLEDGMENTS xv teachers at Sri Venkateshwara College of Engineering (SVCE), and all the professors at IIT Madras—they have molded me into what I am today. I also wish to express my gratitude to Joydeb Mukherjee, formerly senior data scientist with Impetus and currently Senior Technical Specialist at MacAfee. Joydeb reviewed the Introduction chapter of the book and has also been a source of sound-boarding for my ideas when we were working together. This helped establish my beyond- Hadoop ideas firmly. He has also pointed out some of the good work in this field, including the work by Langford et al. I would like to thank Dr. Edd Dumbill, formerly of O’Reilly and now VP at Silicon Valley Data Science—he is the editor of the Big Data journal, where my article was published. He has also been kind enough to review the book. He was also the organizer of the Strata conference in California in February 2013 when I gave a talk about some of the beyond-Hadoop concepts. That talk essentially set the stage for this book. I also take this opportunity to thank the Strata organizers for accepting some of my talk proposals. I also wish to thank Dr. Paco Nathan for reviewing the book and writing up a foreword for it. His comments have been very inspiring, as has his career! He is one of the folks I look up to. Thanks, Paco! My other team members have also been empathetic—Pranav Ganguly, the Senior Architect at Impetus, has taken quite a bit of load off me and taken care of the big data governance thread smoothly. It is a pleasure to have him and Nishant Garg on the team. I wish to thank all my team members. Without a strong family backing, it would have been difficult, if not impossible, to write the book. My wife Vidya played a major role in ensuring the home is peaceful and happy. She has sacrificed signifi- cant time that we could have otherwise spent together to enable me to focus on writing the book. My kids Prahaladh and Purvajaa have been mature enough to let me do this work, too. Thanks to all three xvi BIG DATA ANALYTICS BEYOND HADOOP of them for making a sweet home. I also wish to thank my parents for their upbringing and inculcating morality early in my life. Finally, as is essential, I thank God for giving me everything. I am ever grateful to the almighty for taking care of me. About the Author Vijay Srinivas Agneeswaran, Ph.D., has a Bachelor’s degree in Computer Science & Engineering from SVCE, Madras University (1998), an MS (By Research) from IIT Madras in 2001, and a PhD from IIT Madras (2008). He was a post-doctoral research fellow in the Distributed Information Systems Laboratory (LSIR), Swiss Federal Institute of Technology, Lausanne (EPFL) for a year. He has spent the last seven years with Oracle, Cognizant, and Impetus, contribut- ing significantly to Industrial R&D in the big data and cloud areas. He is currently Director of Big Data Labs at Impetus. The R&D group provides thought leadership through patents, publications, invited talks at conferences, and next generation product innovations. The main focus areas for his R&D include big data governance, batch and real-time analytics, as well as paradigms for implementing machine learning algorithms for big data. He is a professional member of the Association of Computing Machinery (ACM) and the Institute of Electrical and Electronics Engineers (IEEE) for the last eight+ years and was elevated to Senior Member of the IEEE in December 2012. He has filed patents with U.S., European, and Indian patent offices (with two issued U.S. patents). He has published in leading journals and conferences, including IEEE transactions. He has been an invited speaker in several national and international conferences such as O’Reilly’s Strata Big-Data conference series. His recent publi- cations have appeared in the Big Data journal of Liebertpub. He lives in Bangalore with his wife, son, and daughter, and enjoys research- ing ancient Indian, Egyptian, Babylonian, and Greek culture and philosophy. This page intentionally left blank 1 1 Introduction: Why Look Beyond Hadoop Map-Reduce? Perhaps you are a video service provider and would like to opti- mize the end user experience by choosing the appropriate content distribution network based on dynamic network conditions. Or you are a government regulatory body that needs to classify Internet pages into porn or non-porn in order to filter porn pages—which has to be achieved at high throughput and in real-time. Or you are a telecom/ mobile service provider, or you work for one, and you are worried about customer churn ( churn refers to a customer leaving the pro- vider and choosing a competitor, or new customers joining in leaving competitors). How you wish you had known that the last customer who was on the phone with your call center had tweeted with nega- tive sentiments about you a day before. Or you are a retail storeowner and you would love to have predictions about the customers’ buying patterns after they enter the store so that you can run promotions on your products and expect an increase in sales. Or you are a healthcare insurance provider for whom it is imperative to compute the probabil- ity that a customer is likely to be hospitalized in the next year so that you can fix appropriate premiums. Or you are a Chief Technology Officer (CTO) of a financial product company who wishes that you could have real-time trading/predictive algorithms that can help your bottom line. Or you work for an electronic manufacturing company and you would like to predict failures and identify root causes during test runs so that the subsequent real-runs are effective. Welcome to the world of possibilities, thanks to big data analytics. 2 BIG DATA ANALYTICS BEYOND HADOOP Analytics has been around for a long time now—North Carolina State University ran a project called “Statistical Analysis System (SAS)” for agricultural research in the late 1960s that led to the formation of the SAS Company. The only difference between the terms analysis and analytics is that analytics is about analyzing data and convert- ing it into actionable insights. The term Business Intelligence (BI) is also used often to refer to analysis in a business environment, possibly originating in a 1958 article by Peter Luhn (Luhn 1958). Lots of BI applications were run over data warehouses, even quite recently. The evolution of “big data” in contrast to the “analytics” term has been quite recent, as explained next. The term big data seems to have been used first by John R. Mashey, then chief scientist of Silicon Graphics Inc. (SGI), in a Use- nix conference invited talk titled “Big Data and the Next Big Wave of InfraStress,” the transcript of which is available at http://static.usenix. org/event/usenix99/invited_talks/mashey.pdf . The term was also used in a paper (Bryson et al. 1999) published in the Communications of the Association for Computing Machinery (ACM). The report (Laney 2001) from the META group (now Gartner) was the first to iden- tify the 3 Vs (volume, variety, and velocity) perspective of big data. Google’s seminal paper on Map-Reduce (MR; Dean and Ghemawat 2004) was the trigger that led to lots of developments in the big data space. Though the MR paradigm was known in the functional pro- gramming literature, the paper provided scalable implementations of the paradigm on a cluster of nodes. The paper, along with Apache Hadoop, the open source implementation of the MR paradigm, enabled end users to process large data sets on a cluster of nodes—a usability paradigm shift. Hadoop, which comprises the MR imple- mentation, along with the Hadoop Distributed File System (HDFS), has now become the de facto standard for data processing, with a lot of industrial game changers such as Disney, Sears, Walmart, and AT&T having their own Hadoop cluster installations. CHAPTER 1 • INTRODUCTION: WHY LOOK BEYOND HADOOP MAP-REDUCE? 3 Hadoop Suitability Hadoop is good for a number of use cases, including those in which the data can be partitioned into independent chunks—the embarrassingly parallel applications, as is widely known. Hindrances to widespread adoption of Hadoop across Enterprises include the following: • Lack of Object Database Connectivity (ODBC)—A lot of BI tools are forced to build separate Hadoop connectors. • Hadoop’s lack of suitability for all types of applications: • If data splits are interrelated or computation needs to access data across splits, this might involve joins and might not run efficiently over Hadoop. For example, imagine that you have a set of stocks and the set of values of those stocks at vari- ous time points. It is required to compute correlations across stocks—can you check when Apple falls? What is the prob- ability of Samsung too falling the next day? The computation cannot be split into independent chunks—you may have to compute correlation between stocks in different chunks, if the chunks carry different stocks. If the data is split along the time line, you would still need to compute correlation between stock prices at different points of time, which may be in different chunks. • For iterative computations, Hadoop MR is not well-suited for two reasons. One is the overhead of fetching data from HDFS for each iteration (which can be amortized by a distributed caching layer), and the other is the lack of long-lived MR jobs in Hadoop. Typically, there is a termination condition check that must be executed outside of the MR job, so as to deter- mine whether the computation is complete. This implies that new MR jobs need to be initialized for each iteration 4 BIG DATA ANALYTICS BEYOND HADOOP in Hadoop—the overhead of initialization could overwhelm computation for the iteration and could cause significant per- formance hits. The other perspective of Hadoop suitability can be understood by looking at the characterization of the computation paradigms required for analytics on massive data sets, from the National Academies Press (NRC 2013). They term the seven categories as seven “giants” in contrast with the “dwarf” terminology that was used to characterize fundamental computational tasks in the super-computing literature (Asanovic et al. 2006). These are the seven “giants”: 1. Basic statistics: This category involves basic statistical opera- tions such as computing the mean, median, and variance, as well as things like order statistics and counting. The operations are typically O(N) for N points and are typically embarrassingly parallel, so perfect for Hadoop. 2. Linear algebraic computations: These computations involve linear systems, eigenvalue problems, inverses from problems such as linear regression, and Principal Component Analysis (PCA). Linear regression is doable over Hadoop (Mahout has the implementation), whereas PCA is not easy. Moreover, a formulation of multivariate statistics in matrix form is difficult to realize over Hadoop. Examples of this type include kernel PCA and kernel regression. 3. Generalized N-body problems: These are problems that involve distances, kernels, or other kinds of similarity between points or sets of points (tuples). Computational complexity is typically O(N 2 ) or even O(N 3 ). The typical problems include range searches, nearest neighbor search problems, and non- linear dimension reduction methods. The simpler solutions of N-body problems such as k-means clustering are solvable over Hadoop, but not the complex ones such as kernel PCA, kernel CHAPTER 1 • INTRODUCTION: WHY LOOK BEYOND HADOOP MAP-REDUCE? 5 Support Vector Machines (SVM), and kernel discriminant analysis. 4. Graph theoretic computations: Problems that involve graph as the data or that can be modeled graphically fall into this cat- egory. The computations on graph data include centrality, com- mute distances, and ranking. When the statistical model is a graph, graph search is important, as are computing probabilities which are operations known as inference. Some graph theoretic computations that can be posed as linear algebra problems can be solved over Hadoop, within the limitations specified under giant 2. Euclidean graph problems are hard to realize over Hadoop as they become generalized N-body problems. More- over, major computational challenges arise when you are deal- ing with large sparse graphs; partitioning them across a cluster is hard. 5. Optimizations: Optimization problems involve minimiz- ing (convex) or maximizing (concave) a function that can be referred to as an objective, a loss, a cost, or an energy func- tion. These problems can be solved in various ways. Stochas- tic approaches are amenable to be implemented in Hadoop. (Mahout has an implementation of stochastic gradient descent.) Linear or quadratic programming approaches are harder to realize over Hadoop, because they involve complex iterations and operations on large matrices, especially at high dimensions. One approach to solve optimization problems has been shown to be solvable on Hadoop, but by realizing a construct known as All-Reduce (Agarwal et al. 2011). However, this approach might not be fault-tolerant and might not be generalizable. Conjugate gradient descent (CGD), due to its iterative nature, is also hard to realize over Hadoop. The work of Stephen Boyd and his colleagues from Stanford has precisely addressed this giant. Their paper (Boyd et al. 2011) provides insights on how 6 BIG DATA ANALYTICS BEYOND HADOOP to combine dual decomposition and augmented Lagrangian into an optimization algorithm known as Alternating Direction Method of Multipliers (ADMM). The ADMM has been real- ized efficiently over Message Passing Interface (MPI), whereas the Hadoop implementation would require several iterations and might not be so efficient. 6. Integrations: The mathematical operation of integration of functions is important in big data analytics. They arise in Bayesian inference as well as in random effects models. Quadrature approaches that are sufficient for low-dimensional integrals might be realizable on Hadoop, but not those for high- dimensional integration which arise in Bayesian inference approach for big data analytical problems. (Most recent appli- cations of big data deal with high-dimensional data—this is cor- roborated among others by Boyd et al. 2011.) For example, one common approach for solving high-dimensional integrals is the Markov Chain Monte Carlo (MCMC) (Andrieu 2003), which is hard to realize over Hadoop. MCMC is iterative in nature because the chain must converge to a stationary distribution, which might happen after several iterations only. 7. Alignment problems: The alignment problems are those that involve matching between data objects or sets of objects. They occur in various domains—image de-duplication, match- ing catalogs from different instruments in astronomy, multiple sequence alignments used in computational biology, and so on. The simpler approaches in which the alignment problem can be posed as a linear algebra problem can be realized over Hadoop. But the other forms might be hard to realize over Hadoop—when either dynamic programming is used or Hid- den Markov Models (HMMs) are used. It must be noted that dynamic programming needs iterations/recursions. The catalog cross-matching problem can be posed as a generalized N-body problem, and the discussion outlined earlier in point 3 applies. CHAPTER 1 • INTRODUCTION: WHY LOOK BEYOND HADOOP MAP-REDUCE? 7 To summarize, giant 1 is perfect for Hadoop, and in all other giants, simpler problems or smaller versions of the giants are doable in Hadoop—in fact, we can call them dwarfs, Hadoopable problems/ algorithms! The limitations of Hadoop and its lack of suitability for certain classes of applications have motivated some researchers to come up with alternatives. Researchers at the University of Berkeley have proposed “Spark” as one such alternative—in other words, Spark could be seen as the next-generation data processing alternative to Hadoop in the big data space. In the previous seven giants categoriza- tion, Spark would be efficient for • Complex linear algebraic problems (giant 2) • Generalized N-body problems (giant 3), such as kernel SVMs and kernel PCA • Certain optimization problems (giant 4), for example, approaches involving CGD An effort has been made to apply Spark for another giant, namely, graph theoretic computations in GraphX (Xin et al. 2013). It would be an interesting area of further research to estimate the efficiency of Spark for other classes of problems or other giants such as integra- tions and alignment problems. The key idea distinguishing Spark is its in-memory computation, allowing data to be cached in memory across iterations/interactions. Initial performance studies have shown that Spark can be 100 times faster than Hadoop for certain applications. This book explores Spark as well as the other components of the Berkeley Data Analytics Stack (BDAS), a data processing alternative to Hadoop, especially in the realm of big data analytics that involves realizing machine learning (ML) algorithms. When using the term big data analytics, I refer to the capability to ask questions on large data sets and answer them appropriately, possibly by using ML techniques as the foundation. I will also discuss the alternatives to Spark in this space—systems such as HaLoop and Twister. 8 BIG DATA ANALYTICS BEYOND HADOOP The other dimension for which the beyond-Hadoop thinking is required is for real-time analytics. It can be inferred that Hadoop is basically a batch processing system and is not well suited for real-time computations. Consequently, if analytical algorithms are required to be run in real time or near real time, Storm from Twitter has emerged as an interesting alternative in this space, although there are other promising contenders, including S4 from Yahoo and Akka from Type- safe. Storm has matured faster and has more production use cases than the others. Thus, I will discuss Storm in more detail in the later chapters of this book—though I will also attempt a comparison with the other alternatives for real-time analytics. The third dimension where beyond-Hadoop thinking is required is when there are specific complex data structures that need special- ized processing—a graph is one such example. Twitter, Facebook, and LinkedIn, as well as a host of other social networking sites, have such graphs. They need to perform operations on the graphs, for example, searching for people you might know on LinkedIn or a graph search in Facebook (Perry 2013). There have been some efforts to use Hadoop for graph processing, such as Intel’s GraphBuilder. However, as out- lined in the GraphBuilder paper (Jain et al. 2013), it is targeted at construction and transformation and is useful for building the initial graph from structured or unstructured data. GraphLab (Low et al. 2012) has emerged as an important alternative for processing graphs efficiently. By processing, I mean running page ranking or other ML algorithms on the graph. GraphBuilder can be used for construct- ing the graph, which can then be fed into GraphLab for processing. GraphLab is focused on giant 4, graph theoretic computations. The use of GraphLab for any of the other giants is an interesting topic of further research. The emerging focus of big data analytics is to make traditional techniques, such as market basket analysis, scale, and work on large data sets. This is reflected in the approach of SAS and other traditional CHAPTER 1 • INTRODUCTION: WHY LOOK BEYOND HADOOP MAP-REDUCE? 9 vendors to build Hadoop connectors. The other emerging approach for analytics focuses on new algorithms or techniques from ML and data mining for solving complex analytical problems, including those in video and real-time analytics. My perspective is that Hadoop is just one such paradigm, with a whole new set of others that are emerg- ing, including Bulk Synchronous Parallel (BSP)-based paradigms and graph processing paradigms, which are more suited to realize iterative ML algorithms. The following discussion should help clarify the big data analytics spectrum, especially from an ML realization perspec- tive. This should help put in perspective some of the key aspects of the book and establish the beyond-Hadoop thinking along the three dimensions of real-time analytics, graph computations, and batch ana- lytics that involve complex problems (giants 2 through 7). Big Data Analytics: Evolution of Machine Learning Realizations I will explain the different paradigms available for implementing ML algorithms, both from the literature and from the open source community. First of all, here’s a view of the three generations of ML tools available today: 1. The traditional ML tools for ML and statistical analysis, includ- ing SAS, SPSS from IBM, Weka, and the R language. These allow deep analysis on smaller data sets—data sets that can fit the memory of the node on which the tool runs. 2. Second-generation ML tools such as Mahout, Pentaho, and RapidMiner. These allow what I call a shallow analysis of big data. Efforts to scale traditional tools over Hadoop, including the work of Revolution Analytics (RHadoop) and SAS over Hadoop, would fall into the second-generation category. 10 BIG DATA ANALYTICS BEYOND HADOOP 3. The third-generation tools such as Spark, Twister, HaLoop, Hama, and GraphLab. These facilitate deeper analysis of big data. Recent efforts by traditional vendors such as SAS in- memory analytics also fall into this category. First-Generation ML Tools/Paradigms The first-generation ML tools can facilitate deep analytics because they have a wide set of ML algorithms. However, not all of them can work on large data sets—like terabytes or petabytes of data—due to scalability limitations (limited by the nondistributed nature of the tool). In other words, they are vertically scalable (you can increase the processing power of the node on which the tool runs), but not horizontally scalable (not all of them can run on a cluster). The first- generation tool vendors are addressing those limitations by building Hadoop connectors as well as providing clustering options—meaning that the vendors have made efforts to reengineer the tools such as R and SAS to scale horizontally. This would come under the second-/ third-generation tools and is covered subsequently. Second-Generation ML Tools/Paradigms The second-generation tools (we can now term the traditional ML tools such as SAS as first-generation tools) such as Mahout ( http:// mahout.apache.org ), Rapidminer, and Pentaho provide the capabil- ity to scale to large data sets by implementing the algorithms over Hadoop, the open source MR implementation. These tools are matur- ing fast and are open source (especially Mahout). Mahout has a set of algorithms for clustering and classification, as well as a very good rec- ommendation algorithm (Konstan and Riedl 2012). Mahout can thus be said to work on big data, with a number of production use cases, mainly for the recommendation system. I have also used Mahout in a production system for realizing recommendation algorithms CHAPTER 1 • INTRODUCTION: WHY LOOK BEYOND HADOOP MAP-REDUCE? 11 in financial domain and found it to be scalable, though not without issues. (I had to tweak the source significantly.) One observation about Mahout is that it implements only a smaller subset of ML algo- rithms over Hadoop—only 25 algorithms are of production quality, with only 8 or 9 usable over Hadoop, meaning scalable over large data sets. These include the linear regression, linear SVM, the K-means clustering, and so forth. It does provide a fast sequential implementa- tion of the logistic regression, with parallelized training. However, as several others have also noted (see Quora.com, for instance), it does not have implementations of nonlinear SVMs or multivariate logistic regression (discrete choice model, as it is otherwise known). Overall, this book is not intended for Mahout bashing. However, my point is that it is quite hard to implement certain ML algorithms including the kernel SVM and CGD (note that Mahout has an imple- mentation of stochastic gradient descent) over Hadoop. This has been pointed out by several others as well—for instance, see the paper by Professor Srirama (Srirama et al. 2012). This paper makes detailed comparisons between Hadoop and Twister MR (Ekanayake et al. 2010) with regard to iterative algorithms such as CGD and shows that the overheads can be significant for Hadoop. What do I mean by iterative? A set of entities that perform a certain computation, wait for results from neighbors or other entities, and start the next iteration. The CGD is a perfect example of iterative ML algorithm—each CGD can be broken down into daxpy , ddot , and matmul as the primitives. I will explain these three primitives: daxpy is an operation that takes a vector x , multiplies it by a constant k , and adds another vector y to it; ddot computes the dot product of two vectors x and y ; matmul multiplies a matrix by a vector and produces a vector output. This means 1 MR per primitive, leading to 6 MRs per iteration and even- tually 100s of MRs per CG computation, as well as a few gigabytes (GB)s of communication even for small matrices. In essence, the setup cost per iteration (which includes reading from HDFS into 12 BIG DATA ANALYTICS BEYOND HADOOP memory) overwhelms the computation for that iteration, leading to performance degradation in Hadoop MR. In contrast, Twister distin- guishes between static and variable data, allowing data to be in mem- ory across MR iterations, as well as a combine phase for collecting all reduce phase outputs and, hence, performs significantly better. The other second-generation tools are the traditional tools that have been scaled to work over Hadoop. The choices in this space include the work done by Revolution Analytics, among others, to scale R over Hadoop and the work to implement a scalable runtime over Hadoop for R programs (Venkataraman et al. 2012). The SAS in-memory analytics, part of the High Performance Analytics toolkit from SAS, is another attempt at scaling a traditional tool by using a Hadoop cluster. However, the recently released version works over Greenplum/Teradata in addition to Hadoop—this could then be seen as a third-generation approach. The other interesting work is by a small start-up known as Concurrent Systems, which is provid- ing a Predictive Modeling Markup Language (PMML) runtime over Hadoop. PMML is like the eXtensible Markup Language (XML) of modeling, allowing models to be saved in descriptive language files. Traditional tools such as R and SAS allow the models to be saved as PMML files. The runtime over Hadoop would allow these model files to be scaled over a Hadoop cluster, so this also falls in our second- generation tools/paradigms. Third-Generation ML Tools/Paradigms The limitations of Hadoop and its lack of suitability for certain classes of applications have motivated some researchers to come up with alternatives. The efforts in the third generation have been to look beyond Hadoop for analytics along different dimensions. I discuss the approaches along the three dimensions, namely, iterative ML algo- rithms, real-time analytics, and graph processing. CHAPTER 1 • INTRODUCTION: WHY LOOK BEYOND HADOOP MAP-REDUCE? 13 Iterative Machine Learning Algorithms Researchers at the University of Berkeley have proposed “Spark” (Zaharia et al. 2010) as one such alternative—in other words, Spark could be seen as the next-generation data processing alternative to Hadoop in the big data space. The key idea distinguishing Spark is its in-memory computation, allowing data to be cached in memory across iterations/interactions. The main motivation for Spark was that the commonly used MR paradigm, while being suitable for some applications that can be expressed as acyclic data flows, was not suit- able for other applications, such as those that need to reuse working sets across iterations. So they proposed a new paradigm for cluster computing that can provide similar guarantees or fault tolerance (FT) as MR but would also be suitable for iterative and interactive applica- tions. The Berkeley researchers have proposed BDAS as a collection of technologies that help in running data analytics tasks across a clus- ter of nodes. The lowest-level component of the BDAS is Mesos, the cluster manager that helps in task allocation and resource manage- ment tasks of the cluster. The second component is the Tachyon file system built on top of Mesos. Tachyon provides a distributed file sys- tem abstraction and provides interfaces for file operations across the cluster. Spark, the computation paradigm, is realized over Tachyon and Mesos in a specific embodiment, although it could be realized without Tachyon and even without Mesos for clustering. Shark, which is realized over Spark, provides a Structured Query Language (SQL) abstraction over a cluster—similar to the abstraction Hive provides over Hadoop. Zacharia et al. article explores Spark, which is the main ingredient over which ML algorithms can be built. The HaLoop work (Bu et al. 2010) also extends Hadoop for iterative ML algorithms—HaLoop not only provides a program- ming abstraction for expressing iterative applications, but also uses the notion of caching to share data across iterations and for fixpoint verification (termination of iteration), thereby improving efficiency. 14 BIG DATA ANALYTICS BEYOND HADOOP Twister ( http://iterativemapreduce.org ) is another effort similar to HaLoop. Real-time Analytics The second dimension for beyond-Hadoop thinking comes from real-time analytics. Twitter from Storm has emerged as the best con- tender in this space. Storm is a scalable Complex Event Processing (CEP) engine that enables complex computations on event streams in real time. The components of a Storm cluster are • Spouts that read data from various sources. HDFS spout, Kafka spout, and Transmission Control Protocol (TCP) stream spout are examples. • Bolts that process the data. They run the computations on the streams. ML algorithms on the streams typically run here. • Topology. This is an application-specific wiring together of spouts and bolts—topology gets executed on a cluster of nodes. An architecture comprising a Kafka (a distributed queuing sys- tem from LinkedIn) cluster as a high-speed data ingestor and a Storm cluster for processing/analytics works well in practice, with a Kafka spout reading data from the Kafka cluster at high speed. The Kafka cluster stores up the events in the queue. This is necessary because the Storm cluster is heavy in processing due to the ML involved. The details of this architecture, as well as the steps needed to run ML algorithms in a Storm cluster, are covered in subsequent chapters of the book. Storm is also compared to the other contenders in real-time computing, including S4 from Yahoo and Akka from Typesafe. Graph Processing Dimension The other important tool that has looked beyond Hadoop MR comes from Google—the Pregel framework for realizing graph com- putations (Malewicz et al. 2010). Computations in Pregel comprise a CHAPTER 1 • INTRODUCTION: WHY LOOK BEYOND HADOOP MAP-REDUCE? 15 series of iterations, known as supersteps. Each vertex in the graph is associated with a user-defined compute function; Pregel ensures at each superstep that the user-defined compute function is invoked in parallel on each edge. The vertices can send messages through the edges and exchange values with other vertices. There is also the global barrier—which moves forward after all compute functions are ter- minated. Readers familiar with BSP can see why Pregel is a perfect example of BSP—a set of entities computing user-defined functions in parallel with global synchronization and able to exchange messages. Apache Hama (Seo et al. 2010) is the open source equiva- lent of Pregel, being an implementation of the BSP. Hama realizes BSP over the HDFS, as well as the Dryad engine from Micro- soft. It might be that they do not want to be seen as being differ- ent from the Hadoop community. But the important thing is that BSP is an inherently well-suited paradigm for iterative computa- tions, and Hama has parallel implementations of the CGD, which I said is not easy to realize over Hadoop. It must be noted that the BSP engine in Hama is realized over MPI, the father (and mother) of parallel programming literature ( www.mcs.anl.gov/research/ projects/mpi/ ). The other projects that are inspired by Pregel are Apache Giraph, Golden Orb, and Stanford GPS. GraphLab (Gonzalez et al. 2012) has emerged as a state-of-the- art graph processing paradigm. GraphLab originated as an academic project from the University of Washington and Carnegie Mellon Uni- versity (CMU). GraphLab provides useful abstractions for process- ing graphs across a cluster of nodes deterministically. PowerGraph, the subsequent version of GraphLab, makes it efficient to process natural graphs or power law graphs—graphs that have a high number of poorly connected vertices and a low number of highly connected vertices. Performance evaluations on the Twitter graph for page- ranking and triangle counting problems have verified the efficiency of GraphLab compared to other approaches. The focus of this book is mainly on Giraph, GraphLab, and related efforts. 16 BIG DATA ANALYTICS BEYOND HADOOP Table 1.1 carries a comparison of the various paradigms across different nonfunctional features such as scalability, FT, and the algo- rithms that have been implemented. It can be inferred that although the traditional tools have worked on only a single node and might not scale horizontally and might also have single points of failure, recent reengineering efforts have made them move across generations. The other point to be noted is that most of the graph processing para- digms are not fault-tolerant, whereas Spark and HaLoop are among the third-generation tools that provide FT. Table 1.1 Three Generations of Machine Learning Realizations Generation First Generation Second Generation Third Generation Examples Statistical Analysis System (SAS), R, Weka, SPSS in native form Mahout, Pentaho, Revolution R, SAS In-memory Analytics (Hadoop), concurrent systems Spark, HaLoop, GraphLab, Pregel, SAS In-memory Analytics (Greenplum/Teradata), Giraph, Golden ORB, Stanford GPS, ML over Storm Scalability Vertical Horizontal (over Hadoop) Horizontal (beyond Hadoop) Algorithms Available Huge collection of algorithms Small subset— sequential logistic regression, linear SVMs, Stochastic Gradient Descent, K-means clustering, Random Forests, etc. Much wider—including CGD, Alternating Least Squares (ALS), collaborative filtering, kernel SVM, belief propagation, matrix factorization, Gibbs sampling, etc. Algorithms Not Available Practically nothing Vast number— Kernel SVMs, Multivariate Logistic Regression, Conjugate Gradient Descent (CGD), ALS, etc. Multivariate Logistic Regression in general form, K-means clustering, etc.; work in progress to expand the set of algorithms available Fault Tolerance (FT) Single point of failure Most tools are FT, because they are built on top of Hadoop FT: HaLoop, Spark Not FT: Pregel, GraphLab, Giraph CHAPTER 1 • INTRODUCTION: WHY LOOK BEYOND HADOOP MAP-REDUCE? 17 Closing Remarks This chapter has set the tone for the book by discussing the limita- tions of Hadoop along the lines of the seven giants. It has also brought out the three dimensions along which thinking beyond Hadoop is necessary: 1. Real-time analytics: Storm and Spark streaming are the choices. 2. Analytics involving iterative ML: Spark is the technology of choice. 3. Specialized data structures and processing requirements for these: GraphLab is an important paradigm to process large graphs. These are elaborated in the subsequent chapters of this book. Happy reading! References Agarwal, Alekh, Olivier Chapelle, Miroslav Dudík, and John Lang- ford. 2011. “A Reliable Effective Terascale Linear Learning Sys- tem.” CoRR abs/1110.4198. Andrieu, Christopher, N. de Freitas, A. Doucet, and M. I. Jordan. 2003. “An Introduction to MCMC for Machine Learning.” Machine Learning 50(1-2):5-43. Asanovic, K., R. Bodik, B. C. Catanzaro, J. J. Gebis, P. Husbands, K. Keutzer, D. A. Patterson, W. L. Plishker, J. Shalf, S. W. Wil- liams, and K. A. Yelick. 2006. “The Landscape of Parallel Com- puting Research: A View from Berkeley.” University of California, Berkeley, Technical Report No. UCB/EECS-2006-183. Available at www.eecs.berkeley.edu/Pubs/TechRpts/2006/EECS-2006-183. html . Last accessed September 11, 2013. 18 BIG DATA ANALYTICS BEYOND HADOOP Boyd, Stephen, Neal Parikh, Eric Chu, Borja Peleato, and Jonathan Eckstein. 2011. “Distributed Optimization and Statistical Learning via the Alternating Direction Method of Multipliers.” Foundation and Trends in Machine Learning 3(1)(January):1-122. Bryson, Steve, David Kenwright, Michael Cox, David Ellsworth, and Robert Haimes. 1999. “Visually Exploring Gigabyte Data Sets in Real Time.” Communications of the ACM 42(8)(August):82-90. Bu, Yingyi, Bill Howe, Magdalena Balazinska, and Michael D. Ernst. 2010. “HaLoop: Efficient Iterative Data Processing on Large Clusters.” In Proceedings of the VLDB Endowment 3(1-2) (September):285-296. Dean, Jeffrey, and Sanjay Ghemawat. 2008. “MapReduce: Simplified Data Processing on Large Clusters.” In Proceedings of the 6th Con- ference on Symposium on Operating Systems Design and Imple- mentation (OSDI ‘04) . USENIX Association, Berkeley, CA, USA, (6):10-10. Ekanayake, Jaliya, Hui Li, Bingjing Zhang, Thilina Gunarathne, Seung- Hee Bae, Judy Qiu, and Geoffrey Fox. 2010. “Twister: A Runtime for Iterative MapReduce.” In Proceedings of the 19th ACM Inter- national Symposium on High-Performance Distributed Comput- ing . June 21-25, Chicago, Illinois. Available at http://dl.acm.org/ citation.cfm?id=1851593 . Gonzalez, Joseph E., Yucheng Low, Haijie Gu, Danny Bickson, and Carlos Guestrin. 2012. “PowerGraph: Distributed Graph- Parallel Computation on Natural Graphs.” In Proceedings of the 10th USENIX Symposium on Operating Systems Design and Implemen- tation (OSDI ‘12) . Jain, Nilesh, Guangdeng Liao, and Theodore L. Willke. 2013. “GraphBuilder: Scalable Graph ETL Framework.” In First Inter- national Workshop on Graph Data Management Experiences and CHAPTER 1 • INTRODUCTION: WHY LOOK BEYOND HADOOP MAP-REDUCE? 19 Systems (GRADES ‘13) . ACM, New York, NY, USA, (4):6 pages. DOI=10.1145/2484425.2484429. Konstan, Joseph A., and John Riedl. 2012. “Deconstructing Recom- mender Systems.” IEEE Spectrum . Laney, Douglas. 2001. “3D Data Management: Controlling Data Vol- ume, Velocity, and Variety.” Gartner Inc. Retrieved February 6, 2001. Last accessed September 11, 2013. Available at http://blogs. gartner.com/doug-laney/files/2012/01/ad949-3D-Data-Manage- ment-Controlling-Data-Volume-Velocity-and-Variety.pdf . Low, Yucheng, Danny Bickson, Joseph Gonzalez, Carlos Guestrin, Aapo Kyrola, and Joseph M. Hellerstein. 2012. “Distributed GraphLab: A Framework for Machine Learning and Data Min- ing in the Cloud.” In Proceedings of the VLDB Endowment 5(8) (April):716-727. Luhn, H. P. 1958. “A Business Intelligence System.” IBM Journal 2(4):314. doi:10.1147/rd.24.0314. Malewicz, Grzegorz, Matthew H. Austern, Aart J. C. Bik, James C. Dehnert, Ilan Horn, Naty Leiser, and Grzegorz Czajkowski. 2010. “Pregel: A System for Large-scale Graph Processing.” In Proceed- ings of the 2010 ACM SIGMOD International Conference on Management of Data (SIGMOD ‘10) . ACM, New York, NY, USA, 135-146. [NRC] National Research Council. 2013. “Frontiers in Massive Data Analysis.” Washington, DC: The National Academies Press. Perry, Tekla S. 2013. “The Making of Facebook Graph Search.” IEEE Spectrum. Available at http://spectrum.ieee.org/telecom/internet/ the-making-of-facebooks-graph-search . Seo, Sangwon, Edward J. Yoon, Jaehong Kim, Seongwook Jin, Jin-Soo Kim, and Seungryoul Maeng. 2010. “HAMA: An Efficient Matrix Computation with the MapReduce Framework.” In Proceedings of 20 BIG DATA ANALYTICS BEYOND HADOOP the 2010 IEEE Second International Conference on Cloud Com- puting Technology and Science (CLOUDCOM ‘10) . IEEE Com- puter Society, Washington, DC, USA, 721-726. Srirama, Satish Narayana, Pelle Jakovits, and Eero Vainikko. 2012. “Adapting Scientific Computing Problems to Clouds Using MapReduce.” Future Generation Computer System 28(1) (January):184-192. Venkataraman, Shivaram, Indrajit Roy, Alvin AuYoung, and Robert S. Schreiber. 2012. “Using R for Iterative and Incremental Process- ing.” In Proceedings of the 4th USENIX Conference on Hot Topics in Cloud Computing (HotCloud ‘12) . USENIX Association, Berke- ley, CA, USA, 11. Xin, Reynold S., Joseph E. Gonzalez, Michael J. Franklin, and Ion Stoica. 2013. “GraphX: A Resilient Distributed Graph System on Spark.” In First International Workshop on Graph Data Manage- ment Experiences and Systems (GRADES ‘13) . ACM, New York, NY, USA, (2):6 pages. Zaharia, Matei, Mosharaf Chowdhury, Michael J. Franklin, Scott Shenker, and Ion Stoica. 2010. “Spark: Cluster Computing with Working Sets.” In Proceedings of the 2nd USENIX Conference on Hot Topics in Cloud Computing (HotCloud ‘10) . USENIX Associa- tion, Berkeley, CA, USA, 10. This page intentionally left blank Index A actions on Spark RDDs, 33 Akka system, 123 alignment problems, 6 all grouping (Storm), 100 AM (Application Master), 163 - 165 analytics defined, 1 - 2 future of, 166 - 169 history of term, 1 - 2 Apache Hama, 136 application layer in BDAS, 29 - 31 Application Master (AM), 163 - 165 Apply phase (GraphLab vertex program), 151 architecture of BDAS, 26 - 31 of Hadoop YARN, 165 of Mesos, 48 of MLbase, 90 - 91 B basic statistics computations, 4 batch learning, online learning versus, 66 BDAS (Berkeley Data Analytics Stack), 13, 21 design and architecture, 26 - 31 Mesos architecture, 48 cluster resource sharing, 46 - 47 209 fault tolerance, 52 isolation, 50 - 52 resource allocation, 49 - 50 motivation for developing, 21 - 23 Shark, 42 - 46 columnar memory store, 44 - 45 distributed data loading, 45 full partition-wise joins, 45 ML (machine learning) support, 46 partition pruning, 46 Spark extensions for, 43 - 44 Spark data processing in, 31 - 32 DSM (Distributed Shared Memory) systems versus, 38 - 40 expressibility of RDDs, 40 - 41 implementation, 36 - 38 RDDs (resilient distributed datasets), 33 - 36 similar systems, 41 - 42 BI (business intelligence), history of term, 1 - 2 big data future of, 166 - 169 history of term, 2 binary LR (logistic regression), 67 - 69 BLinkDB, 29 - 30 bolts in Storm, 95 - 96 real-time computing example, 97 - 99 BSP (Bulk Synchronous Parallel) applications for, 132 - 134 expressibility through RDDs, 40 210 INDEX Pregel as, 14 - 15 , 130 - 132 limitations, 138 - 139 open source implementations, 134 - 137 bulk iterations, 133 business intelligence (BI), history of term, 1 - 2 C CGD, as iterative ML algorithm, 11 - 12 chromatic engine (GraphLab), 142 classification, regression versus, 66 cluster resource sharing, 25 - 26 , 46 - 47 clusters in Storm, 96 - 97 code sketches, 171 JPMMLLinearRegInSpark.java, 182 NaiveBayesHandler.java, 171 NaiveBayesPMMLBolt.java, 178 sgd.cpp, 191 Simple_pagerank.cpp, 186 columnar memory store in Shark, 44 - 45 complex data structure processing, 8 complex decision planes in SVM, 74 - 76 computation paradigms, list of, 4 - 6 consistency models (GraphLab), 140 - 141 consumers in PMML, 85 - 86 continuous transformations in PMML, 82 Conviva, 30 D data dictionary in PMML, 81 - 82 data management layer in BDAS, 28 - 29 data processing in BDAS, 29 in Spark, 31 - 32 data splits computations, 3 data transformations. See transformations daxpy primitive, 11 ddot primitive, 11 decision trees example (machine learning), 62 - 64 deep learning, 167 dependencies between Spark RDDs, 36 design of BDAS, 26 - 31 design patterns in Storm distributed remote procedure calls (DRPCs), 102 - 106 Trident, 106 - 107 direct grouping (Storm), 100 discrete normalization in PMML, 83 discretization in PMML, 83 disk-based single-node analytics, 168 - 169 distributed data loading in Shark, 45 distributed remote procedure calls (DRPCs), 102 - 106 Distributed Shared Memory (DSM) systems, Spark versus, 38 - 40 distributed SQL systems, Shark as, 42 - 46 distributed version of GraphLab, 141 - 143 Domain Specific Language (DSL), 166 - 167 Dominant Resource Fairness (DRF), 49 Dremel, 123 Drill, 123 DRPCs (distributed remote procedure calls), 102 - 106 DryadLINQ, 40 DSL (Domain Specific Language), 166 - 167 DSM (Distributed Shared Memory) systems, Spark versus, 38 - 40 D-Streams, 124 - 126 INDEX 211 E estimators in logistic regression (LR), 69 - 70 expressibility of RDDs (resilient distributed datasets), 40 - 41 F Facebook graph search, 129 fairness algorithms, 49 - 50 fault tolerance in Mesos, 52 field grouping (Storm), 99 first-generation ML (machine learning) tools, 10 comparison with subsequent generations, 16 Forge, 166 - 167 framework schedulers, 28 , 46 - 47 frameworks over Hadoop YARN, 165 - 166 full partition-wise joins in Shark, 45 future of big data analytics, 166 - 169 G GAS (Gather, Apply, Scatter), 143 - 144 , 149 - 153 Gather phase (GraphLab vertex program), 151 GBASE, 132 generalized N-body problems, 4 Giraph, 134 - 136 , 166 global grouping (Storm), 100 GoldenORB, 136 GPS (Graph Processing System), 137 graph computations, 5 , 8 , 14 - 15 , 129 - 130 applications for, 132 - 134 GraphLab distributed version, 141 - 143 multicore version, 139 - 141 page rank algorithm example, 147 - 153 , 186 - 191 PowerGraph, 143 - 147 stochastic gradient descent example, 153 - 156 , 191 - 207 vertex program, 149 - 153 Hadoop YARN support, 166 with Pregel, 130 - 132 limitations, 138 - 139 open source implementations, 134 - 137 Graph Processing System (GPS), 137 GraphChi, 168 - 169 GraphLab, 15, 138 distributed version, 141 - 143 Hadoop YARN support, 166 multicore version, 139 - 141 page rank algorithm example, 147 - 153 , 186 - 191 PowerGraph, 143 - 147 stochastic gradient descent example, 153 - 156 , 191 - 207 vertex program, 149 - 153 GraphX, 166 grouping Storm streams, 99 - 100 H Hadoop in history of big data analytics, 2 suitability and limitations, 3 - 9 , 21 - 23 , 162 - 163 Hadoop Distributed File System (HDFS), 22 Hadoop YARN, 161 - 162 comparison with Mesos, 28 frameworks for, 165 - 166 motivation for developing, 162 - 163 as resource scheduler, 163 - 165 HaLoop, 13 - 14 , 41 - 42 Hama, 15 header information in PMML, 81 history of big data analytics terminology, 1 - 2 HMMs (Hidden Markov Models), 168 212 INDEX I incremental iterations, 133-134 inductive approach, transductive approach versus, 65 integration problems, 6 interactive queries, 23 - 25 Internet of Things (IoT), 169 Internet traffic filtering example (real-time analytics with Storm), 121 - 122 interrelated data splits computations, 3 IoT (Internet of Things), 169 isolation in Mesos, 50 - 52 iterative computations, 3 - 4 iterative ML algorithms, 13 - 14 expressibility through RDDs, 41 Hadoop YARN support, 166 with Tez, 166 K Kafka clusters, 118 - 120 Kafka spout, 14, 97-98 L limitations of Hadoop, 3 - 9 , 21 - 23 , 162 - 163 of Pregel, 138 - 139 of Spark, 7 linear algebraic computations, 4 linear regression support in PMML, 88 - 89 , 182 - 186 local grouping (Storm), 100 locking engine (GraphLab), 143 logistic regression (LR), 67 - 70 binary LR, 67 - 69 estimators, 69 - 70 multinomial LR, 70 in Spark, 70 - 73 in Storm, 107 - 110 M machine learning (ML) tools. See ML (machine learning) tools machine-to-machine (M2M) data, 116 - 117 Mahout, 10 - 11 , 107 - 108 manufacturing log classification example (real-time analytics with Storm), 116 - 121 Map-Reduce (MR) expressibility through RDDs, 40 parallel databases versus, 24 - 25 Markov Chain Monte Carlo (MCMC), 168 mathematics of SVM (support vector machine), 76 - 78 matmul primitive, 11 MCMC (Markov Chain Monte Carlo), 168 Mesos, 13 architecture, 48 cluster resource sharing, 46 - 47 comparison with Hadoop YARN, 28 fault tolerance, 52 isolation, 50 - 52 motivation for developing, 25 - 26 resource allocation, 49 - 50 message processing guarantees in Storm, 100 - 102 mining schema in PMML, 84 - 85 ML (machine learning), 9 - 16 , 61 comparison of generations, 16 decision trees example, 62 - 64 first-generation tools, 10 Hadoop YARN support, 166 logistic regression (LR). See logistic regression (LR) MLbase, 90 - 91 PMML. See PMML (Predictive Modeling Markup Language) real-time analytics . See also Storm alternatives to Storm, 122 - 123 D-Streams, 124 - 126 INDEX 213 Internet traffic filtering example, 121 - 122 manufacturing log classification example, 116 - 121 Storm example, 97 - 99 second-generation tools, 10 - 12 support in Shark, 46 SVM. See SVM (support vector machine) taxonomy of, 65 - 66 with Tez, 166 third-generation tools, 12 - 16 graph computations, 14 - 15 iterative ML algorithms, 13 - 14 real-time analytics, 14 uses for, 61 - 62 MLbase, 90 - 91 model definition in PMML, 84 monolithic schedulers, 28 MR (Map-Reduce) expressibility through RDDs, 40 parallel databases versus, 23 - 25 multicore version of GraphLab, 139 - 141 multinomial LR (logistic regression), 70 N Naive Bayes support in PMML in Spark, 87 - 88 , 171 - 182 in Storm, 113 - 116 Nectar, 42 Neo4j, 129 - 130 Nimbus, 28 no grouping (Storm), 100 Node Manager (NM), 164 - 165 O Omega, 28 online learning, batch learning versus, 66 Ooyala, 30 - 31 open source implementations of Pregel, 134 - 137 operators, D-Streams, 125 - 126 optimization problems, 5 OS Level virtualization, 51 outputs in PMML, 85 P page rank algorithm example (GraphLab), 147 - 153 , 186 - 191 parallel databases, 23 - 25 ParsePoint, 71-72 partial DAG execution, 43 - 44 partition pruning in Shark, 46 partitioning with PowerGraph, 145 - 147 Pegasus, 132 - 133 Phoebus, 136 Piccolo, 138 PMML (Predictive Modeling Markup Language), 12 linear regression support, 88 - 89 , 182 - 186 Naive Bayes support in Spark, 87 - 88 , 171 - 182 in Storm, 113 - 116 producers and consumers, 85 - 86 structure of, 80 - 85 support in Spark, 79 - 80 PowerGraph, 15 , 143 - 147 Pregel framework, 14 - 15 , 130 - 132 limitations, 138 - 139 open source implementations, 134 - 137 producers in PMML, 85 - 86 Q quantum computing, 168 214 INDEX R R, scaling over Hadoop, 12 random forest (RF) example (machine learning), 62 - 64 RDDs (resilient distributed datasets), 33 - 36 expressibility of, 40 - 41 implementation, 36 - 38 real-time analytics, 7 - 8 , 14 . See also Storm alternatives to Storm, 122 - 123 D-Streams, 124 - 126 Internet traffic filtering example, 121 - 122 manufacturing log classification example, 116 - 121 Storm example, 97 - 99 recommender systems, 61 regression classification versus, 66 linear regression support, in PMML, 88 - 89 , 182 - 186 logistic regression (LR), 67 - 70 binary LR, 67 - 69 estimators, 69 - 70 multinomial LR, 70 in Spark, 70 - 73 in Storm, 107 - 110 reinforcement learning, ML (machine learning) as, 66 Remote Procedure Calls (RPCs), 102 - 104 resilient distributed datasets (RDDs), 33 - 36 expressibility of, 40 - 41 implementation, 36 - 38 resource allocation in Mesos, 49 - 50 resource management layer in BDAS, 26 - 28 Resource Manager (RM), 163 - 165 resource scheduler, Hadoop YARN as, 163 - 165 RF (random forest) example (machine learning), 62 - 64 RM (Resource Manager), 163 - 165 RPCs (Remote Procedure Calls), 102 - 104 S S4 system, 123 Scala, 23 second-generation ML (machine learning) tools, 10 - 12 comparison with other generations, 16 Shark, 13 , 42 - 46 columnar memory store, 44 - 45 distributed data loading, 45 full partition-wise joins, 45 ML (machine learning) support, 46 motivation for developing, 23 - 25 partition pruning, 46 Spark extensions for, 43 - 44 shuffle grouping (Storm), 99 Spark data processing in, 31 - 32 DSM (Distributed Shared Memory) systems versus, 38 - 40 expressibility of RDDs, 40 - 41 extensions for Shark, 43 - 44 Hadoop YARN support, 166 implementation, 36 - 38 as iterative ML algorithm, 13 logistic regression (LR) in, 70 - 73 MLbase, 90 - 91 motivation for developing, 23 PMML support, 79 - 80 for linear regression, 88 - 89 , 182 - 186 for Naive Bayes, 87 - 88 , 171 - 182 RDDs (resilient distributed datasets), 33 - 36 similar systems, 41 - 42 streaming, 124 - 126 suitability and limitations, 7 SVM (support vector machine) in, 78 - 79 INDEX 215 split-data computations, 3 spouts in Storm, 95 - 96 real-time computing example, 97 - 99 SQL interfaces, Shark as, 42 - 46 Stanford GPS (Graph Processing System), 137 stateful operators, D-Streams, 125 - 126 stateless operators, D-Streams, 125 stochastic gradient descent example (GraphLab), 153 - 156 , 190 - 207 Storm, 14, 93 alternatives to, 122 - 123 clusters, 96 - 97 design patterns distributed remote procedure calls (DRPCs), 102 - 106 Trident, 106 - 107 Internet traffic filtering example, 121 - 122 logistic regression (LR) in, 107 - 110 manufacturing log classification example, 116 - 121 message processing guarantees, 100 - 102 PMML support for Naive Bayes, 113 - 116 real-time computing example, 97 - 99 streams, 95 grouping, 99 - 100 support vector machine (SVM) in, 110 - 113 topology, 95 - 96 uses for, 93 - 94 Stratosphere, 133 - 134 streams Spark streaming, 124 - 126 in Storm, 95 grouping, 99 - 100 suitability of Hadoop, 3 - 9 of Spark, 7 supervised learning, ML (machine learning) as, 65 Surfer, 133 SVM (support vector machine), 74 - 79 complex decision planes, 74 - 76 mathematics of, 76 - 78 in Spark, 78 - 79 in Storm, 110 - 113 T Tachyon, 13 targets in PMML, 85 Tez, 165 - 166 third-generation ML (machine learning) tools, 12 - 16 comparison with previous generations, 16 graph computations, 14 - 15 iterative ML algorithms, 13 - 14 real-time analytics, 14 topology of Storm, 95 - 96 transductive approach, inductive approach versus, 65 transformations in PMML, 82 - 84 on Spark RDDs, 33 Trident, 106 - 107 Twister, 14 , 41 - 42 U unsupervised learning, ML (machine learning), 66 V value mapping in PMML, 84 vertex program in GraphLab, 149 - 153 216 INDEX Y-Z Yahoo, 30 YARN, 161 - 162 comparison with Mesos, 28 frameworks for, 165 - 166 motivation for developing, 162 - 163 as resource scheduler, 163 - 165 Zookeeper, 96-97, 134

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