Cloudera Engineering Blog · MapReduce Posts

Improvements in the Hadoop YARN Fair Scheduler

Starting in CDH 4.2, YARN/MapReduce 2 (MR2) includes an even more powerful Fair Scheduler. In addition to doing nearly all that it could do in MapReduce 1 (MR1), the YARN Fair Scheduler can schedule non-MapReduce jobs, schedule based on fine-grained memory instead of slots, and support hierarchical queues. In this post, you’ll learn what the Fair Scheduler’s role is and how it fulfills it, what it means to be a YARN “scheduler,” and dive into its new features and how to get them running on your cluster.

YARN/MR2 vs. MR1

YARN uses an updated terminology to reflect that it no longer just manages resources for MapReduce. From YARN’s perspective, a MapReduce job is an application. YARN schedules containers for map and reduce tasks to live in. What was referred to as pools in the MR1 Fair Scheduler has been updated to queue for consistency with the capacity scheduler. An excellent and deeper explanation is available here.

How Does it Work?

Learn How To Hadoop from Tom White in Dr. Dobb’s

It’s always a great thing for everybody when the experts are willing and eager to share.

So, it’s with special pleasure that I can point you toward a new three-part series by Cloudera’s own Tom White (@tom_e_white) to be published in Dr Dobb’s, which has long been one of the publications of record in the mainstream developer world – from which many original programmers learned basics like BASIC. Now, Dobb’s turns its attention to Apache Hadoop, which says a lot about Hadoop’s continuing adoption.

Cloudera ML: New Open Source Libraries and Tools for Data Scientists

Editor’s note (12/19/2013): Cloudera ML has been merged into the Oryx project. The information below is still valid though.

Last month, Apache Crunch became the fifth project (along with Sqoop, Flume, Bigtop, and MRUnit) to go from Cloudera’s github repository through the Apache Incubator and on to graduate as a top-level project within the Apache Software Foundation. As the founder of the project and a newly minted Apache VP, I wanted to take this opportunity to express my gratitude to the Crunch community, who have taught me that leadership in the Apache Way means service, humility, and investing more time in building a community than I spend writing code. Working with you all on our shared vision is the highlight of every work week.

Creating Analytical Applications with Crunch: Cloudera ML

How Apache Hadoop Helps Scan the Internet for Security Risks

The following guest post comes from Alejandro Caceres, president and CTO of Hyperion Gray LLC – a small research and development shop focusing on open-source software for cyber security.

Imagine this: You’re an informed citizen, active in local politics, and you decide you want to support your favorite local political candidate. You go to his or her new website and make a donation, providing your bank account information, name, address, and telephone number. Later, you find out that the website was hacked and your bank account and personal information stolen. You’re angry that your information wasn’t better protected — but at whom should your anger be directed?

Welcome, KijiMR

The following guest post is provided by Aaron Kimball, CTO of WibiData.

The Kiji ecosystem has grown with the addition of a new module, KijiMR. The Kiji framework is a collection of components that offer developers a handle on building Big Data Applications. In addition to the first release, KijiSchema, we are now proud to announce the availability of a second component: KijiMR. KijiMR allows KijiSchema users to use MapReduce techniques including machine-learning algorithms and complex analytics to develop many kinds of applications using data in KijiSchema. Read on to learn more about the major features included in KijiMR and how you can use them.

Apache Hadoop 2.0.3-alpha Released

Last week the Apache Hadoop PMC voted to release Apache Hadoop 2.0.3-alpha, the latest in the Hadoop 2 release series. This release fixes over 500 issues (covering the Common, HDFS, MapReduce and YARN sub-projects) since the 2.0.2-alpha release in October last year. In addition to bug fixes and general improvements the more noteworthy changes include:

How-To: Run a MapReduce Job in CDH4 using Advanced Features

In my previous post, you learned how to write a basic MapReduce job and run it on Apache Hadoop. In this post, we’ll delve deeper into MapReduce programming and cover some of the framework’s more advanced features. In particular, we’ll explore:

Ph.D. Interns at Cloudera: Bringing Big Data Back to School

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)

Understanding MapReduce via Boggle, Part 2: Performance Optimization

In Part 1 of this series, you learned about MapReduce’s ability to process graphs via the example of Boggle*. The project’s full source code can be found on my GitHub account.

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.

Understanding MapReduce via Boggle

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.

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