presto hadoop

下午对着源码看陆喜恒. Hadoop实战（第2版）6.4.1 （Shuffle和排序）Map端，发现与Hadoop 1.2.1的源码有些出入。下面作个简单的记录，方便起见，引用自书本的语句都用斜体表示。 依书本，从MapTask.java开始。这个类有多个内部类： 从书的描述可知，collect()并不在MapTask类，而在MapOutputBuffer类，其函数功能是 1、定义输出内存缓冲区为环形结构2、定义输出内存缓冲区内容到磁盘的操作 在collect函数中将缓冲区的内容写出时会调用sortAndSpill函数。好了，从这里开始就开始糊涂了，因为collect()没调用这个函数，接触Hadoop也就几天时间，啥都不懂，一下晕了。 简单表示下当前的函数调用关系： 0 ----MapOutputBuffer::co

Prepare the EnvironmentDownload Htrace-core-3.0.4.jar file FirstWebsite Link:http://mvnrepository.com/artifact/org.htrace/htrace-core/3.0.4Copy to the Share/hadoop/common/lib directory in HadoopAvoid errors where you cannot find a file.Download Hadoop2x-eclipse-pluginWebsite address:Https://github.com/winghc/hadoop2x-eclipse-pluginAfter decompression, upload to the server on HadoopIn/home/hadoop/hadoop2x-ec

Generally, one machine in the cluster is specified as namenode, and another machine is specified as jobtracker. These machines areMasters. The remaining Machines serve as datanodeAlsoAs tasktracker. These machines areSlaves Official Address :(Http://hadoop.apache.org/common/docs/r0.19.2/cn/cluster_setup.html) 1 prerequisites Make sure that all required software is installed on each node of your cluster: Sun-JDK, ssh, hadoop Javatm 1.5.x mu

Course Outline and Content introduction:About 35 minutes per lesson, no less than 40 lecturesThe first chapter (11 speak)• Distributed and traditional stand-alone mode· Hadoop background and how it works· Analysis of the working principle of MapReduce• Analysis of the second generation Mr--yarn principle· Cloudera Manager 4.1.2 Installation· Cloudera Hadoop 4.1.2 Installation· CM under the cluster managemen

Hadoop FS: Use the widest range of surfaces to manipulate any file system.Hadoop DFS and HDFs DFS: can only operate on HDFs file system-related (including operations with local FS), which is already deprecated, typically using the latter.The following reference is from StackOverflowFollowing is the three commands which appears same but has minute differences Hadoop fs {args}

Prepare hadoop streaming Hadoop streaming allows you to create and run MAP/reduce jobs with any executable or script as the Mapper and/or the CER Cer. 1. Download hadoop streaming fit for your hadoop version For hadoop2.4.0, you can visit the following website and download the JAR file: Http://mvnrepository.com/art

DISTCP Parallel replication The same version of the Hadoop cluster Hadoop distcp Hdfs//namenode1/foo Hdfs//namenode2/bar Different versions of the Hadoop cluster (HDFs version), executed on the writing side Hadoop distcp Hftp://namenode1:50070/foo Hdfs://namenode2/bar Archive of

Because HDFs is different from a common file system, Hadoop provides a powerful filesystem API to manipulate HDFs. The core classes are Fsdatainputstream and Fsdataoutputstream. Read operation: We use Fsdatainputstream to read the specified file in HDFs (the first experiment), and we also demonstrate the ability to locate the file location of the class, and then start reading the file from the specified location (the second experiment). The code i

1. Introduction:Import the source code to eclipse to easily read and modify the source.2. Description of the environment:MacMVN Tools (Apache Maven 3.3.3)3.hadoop (CDH5.4.2)1. Go to the Hadoop root and execute:MVN org.apache.maven.plugins:maven-eclipse-plugin:2.6: eclipse-ddownloadsources=true - Ddownloadjavadocs=truNote:If you do not specify the version number of Eclipse, you will get the following error,

Environment : Centos7+hadoop2.5.2+hive1.2.1+mysql5.6.22+indigo Service 2 train of thought : Hive load log →hadoop distributed execution → requirement data into MySQL Note : Hadoop log Analysis System on the Internet a lot of data, but most of them have to write a small problem, can not run smoothly, but this article has been personally validated, can be coherent. It also includes a detailed explanation of t

many benefits, such as on-demand and elastic scaling architecture, highly scalable object storage and processing, and adaptive infrastructure. Use the Cloud Big data platform to provide faster production time, agility and infrastructure flexibility, and significantly reduce costs. Virtual Private Cloud (VPC) provides isolated access to computing and storage, as well as security practices. VPC security includes data in cloud storage and network data, as well as role encryption options based on a

After installing the Hadoop pseudo-distributed environment, executing the relevant commands (for example: Bin/hdfs dfs-ls) will appearWARN util. nativecodeloader:unable to load Native-hadoop library for your platform ... using Builtin-java classes where applicable, which is Because the installed Navtive packages and platforms do not match, the Hadoop source packa

Org. apache. hadoop. filecache-*, org. apache. hadoop I don't know why the package is empty. Should the package name be a class for managing File Cache? No information was found on the internet, and no answers were answered from various groups. Hope a Daniel can tell me the answer. Thank you. Why is there no hadoop-*-examplesjar file after the

Hadoop Learning Note 0003--reading data from a Hadoop URLfrom Hadoopurl reading Datato from Hadoop The simplest way to read files in a file system is to use the Java.net.URL object to open a data stream from which to read the data. The general format is as follows:InputStream in = null; try {in = new URL ("Hdfs://host/path"). OpenStream (); Process i

Preface Install the hadoop-2.2.0 64-bit version under Linux CentOS, solve two problems: first, resolve namenode cannot start, view log file logs/ Hadoop-root-namenode-itcast.out (your name is not the same as mine, see the Namenode log file on the line), which throws the following exception:Java.net.BindException:Problem binding to [xxx.xxx.xxx.xxx:9000] Java.net.BindException: Unable to specify the request

Build a Hadoop development environment for Fedora 20 1. configuration information: Operating System: fedora 20X86 Eclipse version: eclipse-jee-helios-SR2-linux-gtk.tar.gz (preferably use Galileo or Helios, otherwise there may be compatibility issues) Hadoop version: hadoop-1.1.2.tar.gz Ant: apache-ant-1.9.3-bin.tar.gz 2. Compile the

First, ready to run the required jar package1) Avro-1.7.4.jar2) Commons-cli-1.2.jar3) Commons-codec-1.4.jar4) Commons-collections-3.2.1.jar5) Commons-compress-1.4.1.jar6) Commons-configuration-1.6.jar7) Commons-io-2.4.jar8) Commons-lang-2.6.jar9) Commons-logging-1.2.jar) Commons-math3-3.1.1.jarOne) Commons-net-3.1.jarCurator-client-2.7.1.jar)Curator-recipes-2.7.1.jar)Gson-2.2.4.jar)Guava-20.0.jar)Hadoop-annotations-2.8.0.jar)

When Hadoop was started today, it was discovered that Datanode could not boot, and the following errors were found in the View log: Java.io.ioexception:file/opt/hadoop/tmp/mapred/system/jobtracker.info could only is replicated to 0 nodes, instead o F 1 at Org.apache.hadoop.hdfs.server.namenode.FSNamesystem.getAdditionalBlock (fsnamesystem.java:1271) at Org.apache.hadoop.hdfs.server.namenode.NameNode.addBl

This morning, I helped a new person remotely build a hadoop cluster (1. in versions X or earlier than 0.22), I am deeply touched. Here I will write down the simplest Apache hadoop construction method and provide help to new users. I will try my best to explain it in detail. Click here to view the avatorhadoop construction steps. 1. Environment preparation: 1 ). machine preparation: the target machine must b

What is hadoop? Before doing something, the first step is to know what, then why, and finally how ). However, after many years of project development, many developers get used to how first, then what, and finally why. This will only make them impetuous, at the same time, technologies are often misused in unsuitable scenarios. The core designs in the hadoop framework are mapreduce and HDFS. The idea of mapre