Looking at the trends in the industry's use of distributed systems and the long-term development of the Hadoop framework, MapReduce's jobtracker/tasktracker mechanism requires massive tweaks to fix its flaws in scalability, memory consumption, threading model, reliability, and performance. The Hadoop development team has done some bug fixes over the past few years, but the cost of these fixes has increased recently, suggesting that it is becoming more difficult to make changes to the original fr
Use PHP and Shell to write Hadoop MapReduce programs. So that any executable program supporting standard I/O (stdin, stdout) can become hadoop er or reducer. For example, copy the code as follows: hadoopjarhadoop-streaming.jar-input makes any executable program that supports standard IO (stdin, stdout) become hadoop mapper or reducer. For example:
The code is as follows:
Hadoop jar hadoop-streaming.jar-input SOME_INPUT_DIR_OR_FILE-output SOME_OUTPUT
Enables any executable program that supports standard IO (stdin, stdout) to be the mapper or reducer of Hadoop. For example:
Copy CodeThe code is as follows:
Hadoop jar Hadoop-streaming.jar-input Some_input_dir_or_file-output Some_output_dir-mapper/bin/cat-reducer/usr/bin /wc
In this case, is it magical to use Unix/linux's own cat and WC tools as mapper/reducer?
If you're used to using some dynamic language to write mapreduce in a dynamic language,
The Official Shuffle Architecture chart
This paper explains the trend and principle of the data from the global macro level.
Refine the schema diagram
Explained the details of Map/reduce from Jobtracker and Tasker.
From the above figure can clearly see the original MapReduce program flow and design ideas:
1 First the user program (Jobclient) submits a job,job message to the job Tracker, the job Tracker is the center of the map-reduce framewor
MapReduce programming Series 7 MapReduce program log view, mapreduce log
First, to print logs without using log4j, you can directly use System. out. println. The log information output to stdout can be found at the jobtracker site.
Second, if you use System. out. println to print the log when the main function is started, you can see it directly on the console.
Directory address for this book Note: http://www.cnblogs.com/mdyang/archive/2011/06/29/data-intensive-text-prcessing-with-mapreduce-contents.html
Currently, the most effective way to process large-scale data is to divide and conquer it ".
Divide and conquer: divide a major problem into several small problems that are relatively independent and then solve them. Because small issues are relatively independent, they can be processed in concurrency or in
26 Preliminary use of clusterDesign ideas of HDFsL Design IdeasDivide and Conquer: Large files, large batches of files, distributed on a large number of servers, so as to facilitate the use of divide-and-conquer method of massive data analysis;L role in Big Data systems:For a variety of distributed computing framework (such as: Mapreduce,spark,tez, ... ) Provides data storage servicesL Key Concepts: File Cut, copy storage, meta data26.1 HDFs Use1. Vie
Great deal. I was supposed to update it yesterday. As a result, I was too excited to receive my new focus phone yesterday and forgot my business. Sorry!
Directory address for this book Note: http://www.cnblogs.com/mdyang/archive/2011/06/29/data-intensive-text-prcessing-with-mapreduce-contents.htmlIntroduction
Mapreduce is very powerful because of its simplicity. Programmers only need to prepare the followin
Learn the difference between mapreduceV1 (previous mapreduce) and mapreduceV2 (YARN) We need to understand MapreduceV1 's working mechanism and design ideas first.First, take a look at the operation diagram of the MapReduce V1The components and functions of the MapReduce V1 are:Client: Clients, responsible for writing MapRedu
Directory address for this book Note: http://www.cnblogs.com/mdyang/archive/2011/06/29/data-intensive-text-prcessing-with-mapreduce-contents.html2.3 execution framework
The greatest thing about mapreduce is that it separates parallel algorithm writing.WhatAndHow(You only need to write a program without worrying about how to execute it)The execution framework makes great contributions to this point: it handl
user data. After years of development, hadoop has become a popular data warehouse. Hammerbacher [68], talked about Facebook's building of business intelligence applications on Oracle databases, and later gave up, because he liked to use his own hadoop-based hive (now an open-source project ). Pig [114] is a platform built with hadoop for massive data analysis and can process structured data like semi-structured data. It was originally developed by Yahoo, but now it is an open-source project.
If
3.1 local Aggregation)
In a data-intensive distributed processing environment, interaction of intermediate results is an important aspect of synchronization from processes that generate them to processes that consume them at the end. In a cluster environment, except for the embarrassing parallel problem, data must be transmitted over the network. In addition, in hadoop, the intermediate result is first written to the local disk and then sent over the network. Because network and disk factors ar
Disclaimer: This article is reproduced from the blog Development team Blog, respect for the original work. This article is suitable for the study of distributed systems, as a background introduction to read. When it comes to distributed systems, you have to mention Google's Troika: Google Fs[1],mapreduce[2],bigtable[3].Although Google did not release the source code for the three products, he released detailed design papers for the three products. I
Directory address for this book Note: http://www.cnblogs.com/mdyang/archive/2011/06/29/data-intensive-text-prcessing-with-mapreduce-contents.html
2.5 Distributed File System HDFSTraditional large-scale data processing problems from the perspective of data placementPrevious focusProcessing. However, if there is no data, there is no way to deal with it.In traditional cluster architecture (such as HPC), computing and storage are two separate components..
MapReduce is one of the first steps to achieve Word Frequency Statistics, mapreduce Word Frequency
Original podcast. If you need to reprint it, please indicate the source. Address: http://www.cnblogs.com/crawl/p/7687120.html
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A large number of
The previous blogs focused on Hadoop's storage HDFs, followed by a few blogs about Hadoop's computational framework MapReduce. This blog mainly explains the specific implementation process of the MapReduce framework, as well as the shuffle process, of course, this technical blog has been particularly numerous and written very good, I wrote a blog before the relevant reading, benefited. The references to som
independent entities.
Entity 1: client, used to submit MapReduce jobs.
Entity 2: jobtracker, used to coordinate the operation of a job.
Entity 3: tasktracker, used to process tasks after job division.
Entity 4: HDFS, used to share job files among other entities.
By reviewing the MapReduce workflow, we can see that the entire MapReduce work process includes the f
line, and the previous part is key, after which it is value. If a "\ t" character is not there, the entire line is treated as a key.2. The sort and partition phases of the MapReduce Shuffler processThe mapper phase, in addition to user code, is most important for the shuffle process, which is the main place where MapReduce takes time and consumes resources because it involves operations such as Disk writes
3.2 pairs (pair) and stripes (stripe)
A common practice of synchronization in mapreduce programs is to adapt data to the execution framework by building complex keys and values. We have covered this technology in the previous chapter, that is, "package" the total number and count into a composite value (for example, pair) from Mapper to combiner and then to Cer. Based on previous publications (54,94), this section describes two common design patterns
Directory address for this book Note: http://www.cnblogs.com/mdyang/archive/2011/06/29/data-intensive-text-prcessing-with-mapreduce-contents.html
3.4 secondary sorting
Before intermediate results enter CER, mapreduce first sorts these intermediate results and then distributes them. This mechanism is very convenient for reduce operations that depend on the input sequence of intermediate results (in the o
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