Cloudera Engineering Blog · Hadoop Posts
Organizations of all types and sizes are waking up to the idea that integrating the Apache Hadoop stack into their IT infrastructure solves very common, near-term data management problems. At the same time, deploying Hadoop offers the long-term promise of rapid innovation via Big Data analytics. But, how do you get from Point A to Point Z with the least possible exposure to risk?
Coming to a U.S. city near you, The Cloudera Sessions are single-day, interactive events – with presentations in the morning, and technical breakouts in the afternoon – designed to help you identify where you are on your journey with Apache Hadoop, and how to keep that journey going in a low-risk, productive way. You’ll benefit not only from Cloudera’s experiences with real-world deployments, but also hear directly from some of the Hadoop users who planned and manage them.
In this installment of “Meet the Engineer”, get to know Customer Operations Engineering Manager/Apache Sqoop committer Kathleen Ting (@kate_ting).
What do you do at Cloudera, and in what open-source projects are you involved?
I’m a support manager at Cloudera, and an Apache Sqoop committer and PMC member. I also contribute to the Apache Flume and Apache ZooKeeper mailing lists and organize and present at meetups, as well as speak at conferences, about those projects.
Cloudera Impala, the open-source real-time query engine for Apache Hadoop, uses many tools and techniques to get the best query performance. This blog post will discuss how we use runtime code generation to significantly improve our CPU efficiency and overall query execution time. We’ll explain the types of inefficiency that code-generation eliminates and go over in more detail one of the queries in the TPCH workload where code generation improves overall query speeds by close to 3x.
Why Code Generation?
The baseline for “optimal” query engine performance is a native application that is written specifically for your data format, written only to support your query. For example, it would be ideal if a query engine could execute this query:
Introduction: Training is Key
Apache Hadoop is extremely important to maximizing the value Syncsort’s technology delivers to our customers. That value promise starts with a solid foundation of knowledge and skills among key technical staff across the company.
The following is a series of stories from people who in the recent past worked as Engineering Interns at Cloudera. These experiences concretely illustrate how collaboration between commercial companies like Cloudera and academia, such as in the form of these internships, helps promote big data research at universities. (These experiences were previously published in the ACM student journal, XRDS.)
Yanpei Chen (Intern 2011)
The example comprised a 4×4 matrix of letters, which doesn’t come close to the number of relationships in a large graph. To calculate the number of possible combinations, we turned off the Bloom Filter with “
-D bloom=false“. This enters a brute-force mode where all possible combinations in the graph are traversed. In a 4×4 or 16-letter matrix, there are 11,686,456 combinations, and a 5×5 or 25-letter matrix has 9,810,468,798 combinations.
Are you new to Apache Hadoop and need to start processing data fast and effectively? Have you been playing with CDH and are ready to move on to development supporting a technical or business use case? Are you prepared to unlock the full potential of all your data by building and deploying powerful Hadoop-based applications?
Cloudera University is the world leader in Apache Hadoop training and certification. Our full suite of live courses and online materials is the best resource to get started with your Hadoop cluster in development or advance it towards production. We offer deep industry insight into the skills and expertise required to establish yourself as a leading Developer or Administrator managing and processing Big Data in this fast-growing field.
But did you know Cloudera training can also help you plan for the advanced stages and progress of your Hadoop cluster? In addition to core training for Developers and Administrators, we also offer the best (and, in some cases, only) opportunity to get up to speed on lifecycle projects within the Hadoop ecosystem in a classroom setting. Cloudera University’s course offerings go beyond the basics to include Training for Apache HBase, Training for Apache Hive and Pig, and Introduction to Data Science: Building Recommender Systems. Depending on your Big Data agenda, Cloudera training can help you increase the accessibility and queryability of your data, push your data performance towards real-time, conduct business-critical analyses using familiar scripting languages, build new applications and customer-facing products, and conduct data experiments to improve your overall productivity and profitability.
The Hadoop Community is an invariably fascinating world. After all, as Clouderan ATM put it in a past blog post, the user group meetups are adorably called “HUGs.” Just as the Cloudera blog has introduced you to some of the engineers, projects, and applications that serve as the head, heart, and hands of the Hadoop Community, we’re proud to add the circulatory system (to extend the metaphor), made up of Cloudera’s expert trainers and curriculum developers who bring Hadoop to new practitioners around the world every week.
Welcome to the first installment of our “Meet the Instructor” series, in which we briefly introduce you to some of the individuals endeavoring to teach Hadoop far and wide. Today, we speak to Jesse Anderson (@jessetanderson)!
Graph theory is a growing part of Big Data. Using graph theory, we can find relationships in networks.
MapReduce is a great platform for traversing graphs. Therefore, one can leverage the power of an Apache Hadoop cluster to efficiently run an algorithm on the graph.
For several good reasons, 2013 is a Happy New Year for Apache Hadoop enthusiasts.
In 2012, we saw continued progress on developing the next generation of the MapReduce processing framework (MRv2), work that will bear fruit this year. HDFS experienced major progress toward becoming a lights-out, fully enterprise-ready distributed filesystem with the addition of high availability features and increased performance. And a hint of the future of the Hadoop platform was provided with the Beta release of Cloudera Impala, a real-time query engine for analytics across HDFS and Apache HBase data.
(Update 2/6/2013 – Sorry, this event is sold out!)
With Strata Conference 2013 coming to town (Feb. 26-28, in Santa Clara, Calif.), we thought it would be a great opportunity to open our Palo Alto office’s doors for a pre-conference “Data Hacking Day” on Monday, Feb. 25!
Start the year off with bigger questions by taking advantage of Cloudera University’s special offer for aspiring Hadoop administrators. All participants who complete a Cloudera Administrator Training for Apache Hadoop public course by the end of March 2013 will receive a free digital copy of Hadoop Operations by Eric Sammer. If you’ve been asked to maintain large and complex Hadoop clusters, this book is a must. In addition to providing practical guidance from an expert, Hadoop Operations is also a terrific companion reference to the full Cloudera Administrator course.
Cloudera’s three-day course provides administrators a comprehensive understanding of all the steps necessary to operate and manage Hadoop clusters. From installation and configuration through load balancing and tuning your cluster, Cloudera’s administration course has you covered. This course is appropriate for system administrators and others who will be setting up or maintaining a Hadoop cluster. Basic Linux experience is a prerequisite, but prior knowledge of Hadoop is not required.
I recently joined Cloudera after working in computational biology/genomics for close to a decade. My analytical work is primarily performed in Python, along with its fantastic scientific stack. It was quite jarring to find out that the Apache Hadoop ecosystem is primarily written in/for Java. So my first order of business was to investigate some of the options that exist for working with Hadoop from Python.
In this post, I will provide an unscientific, ad hoc review of my experiences with some of the Python frameworks that exist for working with Hadoop, including:
It’s been an exciting month and a half since the launch of the Cloudera Impala (the new open source distributed query engine for Apache Hadoop) beta, and we thought it’d be a great time to provide an update about what’s next for the project – including our product roadmap, release schedule and open-source plan.
First of all, we’d like to thank you for your enthusiasm and valuable beta feedback. We’re actively listening and have already fixed many of the bugs reported, captured feature requests for the roadmap, and updated the Cloudera Impala FAQ based on user input.
At Cloudera, we put great pride into drinking our own champagne. That pride extends to our support team, in particular.
Cloudera Manager, our end-to-end management platform for CDH (Cloudera’s open-source, enterprise-ready distribution of Apache Hadoop and related projects), has a feature that allows subscription customers to send a snapshot of their cluster to us. When these cluster snapshots come to us from customers, they end up in a CDH cluster at Cloudera where various forms of data processing and aggregation can be performed.
We are very pleased to introduce new, CDH4.1-aligned versions of the Cloudera Certified Developer for Apache Hadoop and Cloudera Certified Administrator for Apache Hadoop exams.
To celebrate, we’re offering a steep 40% discount on the new exams until the end of the year! Just use the promotion code CDH4 when you register to take the CCD-410 or CCA-410 exam through Pearson VUE before Dec. 31, 2012.
The following post was originally published via blog.apache.org; we are re-publishing it here.
Apache Flume was conceived as a fault-tolerant ingest system for the Apache Hadoop ecosystem. Flume comes packaged with an HDFS Sink which can be used to write events into HDFS, and two different implementations of HBase sinks to write events into Apache HBase. You can read about the basic architecture of Apache Flume 1.x in this blog post. You can also read about how Flume’s File Channel persists events and still provides extremely high performance in an earlier blog post. In this article, we will explore how to configure Flume to write events into HBase, and write custom serializers to write events into HBase in a format of the user’s choice.
Announcing the Kiji Project: An Open Source Framework for Building Big Data Applications with Apache HBase
The following is a guest post from Aaron Kimball, who was Cloudera’s first engineer and the creator of the Apache Sqoop project. He is the Founder and CTO at WibiData, a San Francisco-based company building big data applications.
Our team at WibiData has been developing applications on Hadoop since 2010 and we’ve helped many organizations transform how they use data by deploying Hadoop. HBase in particular has allowed companies of all types to drive their business using scalable, high performance storage. Organizations have started to leverage these capabilities for various big data applications, including targeted content, personalized recommendations, enhanced customer experience and social network analysis.
This is the third article in a series about analyzing Twitter data using some of the components of the Apache Hadoop ecosystem that are available in CDH (Cloudera’s open-source distribution of Apache Hadoop and related projects). If you’re looking for an introduction to the application and a high-level view, check out the first article in the series.
In the previous article in this series, we saw how Flume can be utilized to ingest data into Hadoop. However, that data is useless without some way to analyze the data. Personally, I come from the relational world, and SQL is a language that I speak fluently. Apache Hive provides an interface that allows users to easily access data in Hadoop via SQL. Hive compiles SQL statements into MapReduce jobs, and then executes them across a Hadoop cluster.
Today we bring you a brief interview with Alex Holmes, author of the new book, Hadoop in Practice (Manning). You can learn more about the book and download a free sample chapter here.
There are a few good Hadoop books on the market right now. Why did you decide to write this book, and how is it complementary to them?
When I started working with Hadoop I leaned heavily on Tom White’s excellent book, Hadoop: The Definitive Guide (O’Reilly Media), to learn about MapReduce and how the internals of Hadoop worked. As my experience grew and I started working with Hadoop in production environments I had to figure out how to solve problems such as moving data in and out of Hadoop, using compression without destroying data locality, performing advanced joining techniques and so on. These items didn’t have a lot of coverage in existing Hadoop books, and that’s really the idea behind Hadoop in Practice – it’s a collection of real-world recipes that I learned the hard way over the years.
Today we’re proud to announce a new addition to the Apache Hadoop ecosystem: Cloudera Impala, a parallel SQL engine that runs natively on Hadoop storage. The salient points are:
Earlier this month the Apache Hadoop PMC released Apache Hadoop 2.0.2-alpha, which fixes over 600 issues since the previous release in the 2.0 series, 2.0.1-alpha, back in July. This is a tremendous rate of development, of which all contributors to the project should feel proud.
Some of the more noteworthy changes in this release include:
This is the second article in a series about analyzing Twitter data using some of the components of the Hadoop ecosystem available in CDH, Cloudera’s open-source distribution of Apache Hadoop and related projects. In the first article, you learned how to pull CDH components together into a single cohesive application, but to really appreciate the flexibility of each of these components, we need to dive deeper.
Every story has a beginning, and every data pipeline has a source. So, to build Hadoop applications, we need to get data from a source into HDFS.
In this installment of “Meet the Engineers”, meet Todd Lipcon (@tlipcon), PMC member/committer for the Hadoop, HBase, and Thrift projects.
Metrics are collections of information about Hadoop daemons, events and measurements; for example, data nodes collect metrics such as the number of blocks replicated, number of read requests from clients, and so on. For that reason, metrics are an invaluable resource for monitoring Apache Hadoop services and an indispensable tool for debugging system problems.
This blog post focuses on the features and use of the Metrics2 system for Hadoop, which allows multiple metrics output plugins to be used in parallel, supports dynamic reconfiguration of metrics plugins, provides metrics filtering, and allows all metrics to be exported via JMX.
Metrics vs. MapReduce Counters
This guest post is provided by Dan McClary, Principal Product Manager for Big Data and Hadoop at Oracle.
One of the constants in discussions around Big Data is the desire for richer analytics and models. However, for those who don’t have a deep background in statistics or machine learning, it can be difficult to know not only just what techniques to apply, but on what data to apply them. Moreover, how can we leverage the power of Apache Hadoop to effectively operationalize the model-building process? In this post we’re going to take a look at a simple approach for applying well-known machine learning approaches to our big datasets. We’ll use Pig and Hadoop to quickly parallelize a standalone machine-learning program written in Jython.
Update time! As a reminder, Cloudera releases major versions of CDH, our 100% open source distribution of Apache Hadoop and related projects, annually and then updates to CDH every three months. Updates primarily comprise bug fixes but we will also add enhancements. We only include fixes or enhancements in updates that maintain compatibility, improve system stability and still allow customers and users to skip updates as they see fit.
We’re pleased to announce the availability of CDH4.1. We’ve seen excellent adoption of CDH4.0 since it went GA at the end of June and a number of exciting use cases have moved to production. CDH4.1 is an update that has a number of fixes but also a number of useful enhancements. Among them:
For those of you new to it, the Duke’s Choice Awards program was initiated by Sun Microsystems in 2002 in an effort to “celebrate extreme innovation in the world of Java technology” – in essence, it’s the “MVP” of the Java ecosystem. Since it acquired Sun in 2009, Oracle has continued the tradition of bestowing the award, and in fact has made the process more community-oriented by accepting nominations from the public and involving Java User Groups in the judging effort.
For the 2012 awards, I’m happy to report that Apache Hadoop is among the awardees - which also include the United Nations High Commission for Refugees, Liquid Robotics, and Java cloud company Jelastic Inc., among others.
We’re getting really close to Strata Conference + Hadoop World 2012 (just over a month away), schedule planning-wise. So you may want to consider adding the tutorials, sessions, and keynotes below to your calendar! (Start times are always subject to change of course.)
The ones listed below are led or co-led by Clouderans, but there is certainly a wide range of attractive choices beyond what you see here. We just want to ensure that you put these particular ones high on your consideration list.
Strata Conference + Hadoop World (Oct. 23-25 in New York City) is a bonanza for Hadoop and big data enthusiasts – but not only because of the technical sessions and tutorials. It’s also an important gathering place for the developer community, most of whom are eager to share info from their experiences in the “trenches”.
Just to make that process easier, Cloudera is teaming up with local meetups during that week to organize a series of meetings on a variety of topics. (If for no other reason, stop into one of these meetups for a chance to grab a coveted Cloudera t-shirt.)
API access was a new feature introduced in Cloudera Manager 4.0 (download free edition here.). Although not visible in the UI, this feature is very powerful, providing programmatic access to cluster operations (such as configuration and restart) and monitoring information (such as health and metrics). This article walks through an example of setting up a 4-node HDFS and MapReduce cluster via the Cloudera Manager (CM) API.
Cloudera Manager API Basics
The CM API is an HTTP REST API, using JSON serialization. The API is served on the same host and port as the CM web UI, and does not require an extra process or extra configuration. The API supports HTTP Basic Authentication, accepting the same users and credentials as the Web UI. API users have the same privileges as they do in the web UI world.
Organizations in diverse industries have adopted Apache Hadoop-based systems for large-scale data processing. As a leading force in Hadoop development with customers in half of the Fortune 50 companies, Cloudera is in a unique position to characterize and compare real-life Hadoop workloads. Such insights are essential as developers, data scientists, and decision makers reflect on current use cases to anticipate technology trends.
Recently we collaborated with researchers at UC Berkeley to collect and analyze a set of Hadoop traces. These traces come from Cloudera customers in e-commerce, telecommunications, media, and retail (Table 1). Here I will explain a subset of the observations, and the thoughts they triggered about challenges and opportunities in the Hadoop ecosystem, both present and in the future.
Today ZDNet has very helpfully published a guide to downloading, configuring, and using Cloudera’s Demo VM for CDH4 (available in three flavors, but in this case the VMware version). As the author, Andrew Brust, explains, the VM contains a “pre-built, training-appropriate, 1-node Apache Hadoop cluster” (on top of CentOS). Perhaps most important for boot-strappers, it’s free.
As I mentioned in my inaugural post last week, it’s important to shine a spotlight on the Cloudera engineers who have a hand in making the Hadoop projects run. It’s an obvious point, and yet an overlooked one, that a community is an aggregation of individual personalities who have diverse backgrounds and interests yet a shared passion for the group and its goals. As Jono Bacon puts it in his seminal 2009 book The Art of Community, “The building blocks of a community are its teams, and the material that makes these blocks are people.”
In June 2012, Eli Collins (@elicollins), from Cloudera’s Platforms team, led a session at QCon New York 2012 on the subject “Introducing Apache Hadoop: The Modern Data Operating System.” During the conference, the QCon team had an opportunity to interview Eli about several topics, including important things to know about CDH4, main differences between MapReduce 1.0 and 2.0, Hadoop use cases, and more. It’s a great primer for people who are relatively new to Hadoop.
You can catch the full interview (video and transcript versions) here.
We are happy to announce the general availability of CDH3 update 5. This update is a maintenance release of CDH3 platform and provides a considerable amount of bug-fixes and stability enhancements. Alongside these fixes, we have also included a few new features, most notable of which are the following:
This post was contributed by Bob Gourley, editor, CTOvision.com.
You are no doubt aware of the interesting situation we face with data today: The amount of data being created is growing faster than humans can analyze, but fast analysis over data can help humanity solve some very tough challenges. This fact is moving the globe towards new “Big Data” solutions.
Government use of Big Data is of particular note.
Up to this point, we’ve described our reasons for using Hadoop and Hive on our neural recordings (Part I), the reasons why the analyses of these recordings are interesting from a scientific perspective, and detailed descriptions of our implementation of these analyses using Apache Hadoop and Apache Hive (Part II). The last part of this story cuts straight to the results and then discusses important lessons we learned along the way and future goals for improving the analysis framework we’ve built so far.
Here are two plots of the output data from our benchmark run. Both plots show the same data, one in three dimensions and the other in a two-dimensional density format.
As mentioned in Part I, although Apache Hadoop and other Big Data technologies are typically applied to I/O intensive workloads, where parallel data channels dramatically increase I/O throughput, there is growing interest in applying these technologies to CPU intensive workloads. In this work, we used Hadoop and Hive to digitally signal process individual neuron voltage signals captured from electrodes embedded in the rat brain. Previously, this processing was performed on a single Matlab workstation, a workload that was both CPU intensive and data intensive, especially for intermediate output data. With Hadoop and Apache Hive, we were not only able to apply parallelism to the various processing steps, but had the additional benefit of having all the data online for additional ad hoc analysis. Here, we describe the technical details of our implementation, including the biological relevance of the neural signals and analysis parameters. In Part III, we will then describe the tradeoffs between the Matlab and Hadoop/Hive approach, performance results, and several issues identified with using Hadoop/Hive in this type of application.
For this work, we used a university Hadoop computing cluster. Note that it is blade-based, and is not an ideal configuration for Hadoop because of the limited number (2) of drive bays per node. It has these specifications:
In this three-part series of posts, we will share our experiences tackling a scientific computing challenge that may serve as a useful practical example for those readers considering Apache Hadoop and Apache Hive as an option to meet their growing technical and scientific computing needs. This first part describes some of the background behind our application and the advantages of Hadoop that make it an attractive framework in which to implement our solution. Part II dives into the technical details of the data we aimed to analyze and of our solution. Finally, we wrap up this series in Part III with a description of some of our main results, and most importantly perhaps, a list of things we learned along the way, as well as future possibilities for improvements.
About a year ago, after hearing increasing buzz about big data in general, and Hadoop in particular, I (Brad Rubin) saw an opportunity to learn more at our Twin Cities (Minnesota) Java User Group. Brock Noland, the local Cloudera representative, gave an introductory talk. I was really intrigued by the thought of leveraging commodity computing to tackle large-scale data processing. I teach several courses at the University of St. Thomas Graduate Programs in Software, including one in information retrieval. While I had taught the abstract principles behind the scale and performance solutions for indexing web-sized document collections, I saw an opportunity to integrate a real-world solution into the course.
At 5 pm PDT on June 30, a leap second was added to the Universal Coordinated Time (UTC). Within an hour, Cloudera Support started receiving reports of systems running at 100% CPU utilization. The Support Team worked quickly to understand and diagnose the problem and soon published a solution. Bugs due to the leap second coupled with the Amazon Web Services outage would make this Cloudera’s busiest support weekend to date.
Since Hadoop is written in Java and closely interoperates with the underlying OS, Cloudera Support troubleshoots not only all 17 components in the Hadoop ecosystem, but also any underlying Linux and Java bugs. Last weekend many of our customers were affected by the now infamous “leap second” bugs. Initially, many assumed that Java and Linux would process the leap second gracefully. However, we soon discovered that this wasn’t the case and depending on the version of Linux being used, several distinct issues were observed.
This is a guest re-post from Datameer’s Director of Marketing, Rich Taylor. The original post can be found on the Datameer blog.
Datameer uses D3.js to power our Business Infographic™ designer. I thought I would show how we visualized the Apache Hadoop ecosystem connections. First using only D3.js, and second using Datameer 2.0.
Apache Flume is a scalable, reliable, fault-tolerant, distributed system designed to collect, transfer, and store massive amounts of event data into HDFS. Apache Flume recently graduated from the Apache Incubator as a Top Level Project at Apache. Flume is designed to send data over multiple hops from the initial source(s) to the final destination(s). Click here for details of the basic architecture of Flume. In this article, we will discuss in detail some new components in Flume 1.x (also known as Flume NG), which is currently on the trunk branch, techniques and components that can be be used to route the data, configuration validation, and finally support for serializing events.
In the past several months, contributors have been busy adding several new sources, sinks and channels to Flume. Flume now supports Syslog as a source, where sources have been added to support Syslog over TCP and UDP.
This week, a team of researchers at Google will be presenting a paper describing a system they developed that can learn to identify objects, including the faces of humans and cats, from an extremely large corpus of unlabeled training data. It is a remarkable accomplishment, both in terms of the system’s performance (a 70% improvement over the prior state-of-the-art) and its scale: the system runs on over 16,000 CPU cores and was trained on 10 million 200×200 pixel images extracted from YouTube videos.
Doug Cutting has described Apache Hadoop as “the kernel of a distributed operating system.” Until recently, Hadoop has been an operating system that was optimized for running a certain class of applications: the ones that could be structured as a short sequence of MapReduce jobs. Although MapReduce is the workhorse programming framework for distributed data processing, there are many difficult and interesting problems– including combinatorial optimization problems, large-scale graph computations, and machine learning models that identify pictures of cats– that can benefit from a more flexible execution environment.
This is a guest post by Assaf Yardeni, Head of R&D for Treato, an online social healthcare solution, headquartered in Israel.
Three years ago I joined Treato, a social healthcare analysis firm to help treato.com scale up to its present capability. Treato is a new source for healthcare information where health-related user generated content (UGC) from the Internet is aggregated and organized into usable insights for patients, physicians and other healthcare professionals. With oceans of patient-written health-related information available on the Web, and more being published each day, Treato needs to be able to collect and process vast amounts of data – Treato is Big Data par excellence, and my job has been to bring Treato to this stage.
Before the Hadoop era
San Francisco seems to be having an unusually high number of flu cases/searches this April, and the Cloudera Data Science Team has been hit pretty hard. Our normal activities (working on Crunch, speaking at conferences, finagling a job with the San Francisco Giants) have taken a back seat to bed rest, throat lozenges, and consuming massive quantities of orange juice. But this bit of downtime also gave us an opportunity to focus on solving a large-scale data science problem that helps some of the people who help humanity the most: epidemiologists.
A case-control study is a type of observational study in which a researcher attempts to identify the factors that contribute to a medical condition by comparing a set of subjects who have that condition (the ‘cases’) to a set of subjects who do not have the condition, but otherwise resemble the case subjects (the ‘controls’). They are useful for exploratory analysis because they are relatively cheap to perform, and have led to many important discoveries- most famously, the link between smoking and lung cancer.
This blog was originally posted on the Apache Blog:
Cloudera hosted the Apache Sqoop Meetup last week at Cloudera HQ in Palo Alto. About 20 of the Meetup attendees had not used Sqoop before, but were interested enough to participate in the Meetup on April 4th. We believe this healthy interest in Sqoop will contribute to its wide adoption.
Apache Bigtop 0.3.0 (incubating) is now available. This is the first fully integrated, community-driven, 100% Apache Big Data management distribution based on Apache Hadoop 1.0. In addition to a major change in the Hadoop version, all of the Hadoop ecosystem components have been upgraded to the latest stable versions and thoroughly tested:
A few months ago, my colleague Charles Zedlewski wrote a great piece explaining Apache Hadoop version numbering. The post can be summed up with the following diagram: