Hadoop2.x介绍与源码编译

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1、Hadoop 项目的四大模块

Hadoop Common: The common utilities that support the other Hadoop modules.
Hadoop Distributed File System (HDFS™): A distributed file system that provides high-throughput access to application data.
Hadoop YARN: A framework for job scheduling and cluster resource management.
Hadoop MapReduce: A YARN-based system for parallel processing of large data sets.

2、YARN：”云的操作系统”-- Hortonworks （Hadoop 商业版本的）

给部署在YARN上的应用，分配资源
管理资源
JOB/APPLICATION 调度

3、技能

云计算，Hadoop 2.x
服务总线，SOA/OSB，Dubble
全文检索，Lucunce、Solr、Nutch

4、编译Hadoop 2.x 源码

4.1、环境：

1）Linux 64 位操作系统，CentOS 6.4 版本，VMWare 搭建的虚拟机

2）虚拟机可以联网

4.2、官方编译说明：

解压命令：tar -zxvf hadoop-2.2.0-src.tar.gz

之后进入到解压文件夹下，可以查看BUILDING.txt文件， more BUILDING.txt ，向下翻页是空格键，其中内容如下

Requirements:

* Unix System

* JDK 1.6+

* Maven 3.0 or later

* Findbugs 1.3.9 (if running findbugs)

* ProtocolBuffer 2.5.0

* CMake 2.6 or newer (if compiling native code)

* Internet connection for first build (to fetch all Maven and Hadoop dependencies)

----------------------------------------------------------------------------------

Maven main modules:

hadoop (Main Hadoop project)

- hadoop-project (Parent POM for all Hadoop Maven modules. )

(All plugins & dependencies versions are defined here.)

- hadoop-project-dist (Parent POM for modules that generate distributions.)

- hadoop-annotations (Generates the Hadoop doclet used to generated the Java

docs)

- hadoop-assemblies (Maven assemblies used by the different modules)

- hadoop-common-project (Hadoop Common)

- hadoop-hdfs-project (Hadoop HDFS)

- hadoop-mapreduce-project (Hadoop MapReduce)

- hadoop-tools (Hadoop tools like Streaming, Distcp, etc.)

- hadoop-dist (Hadoop distribution assembler)

----------------------------------------------------------------------------------

在编译完成之后，可以查看Hadoop的版本信息

libhadoop.so.1.0.0: ELF 64-bit LSB shared object, x86-64, version 1 (SYSV), dynamically linked, not stripped
[root@centos native]# pwd
/opt/hadoop-2.2.0-src/hadoop-dist/target/hadoop-2.2.0/lib/native
[root@centos native]#

4.3、编译前准备之安装依赖包

安装linux系统包

yum install autoconf automake libtool cmake
yum install ncurses-devel
yum install openssl-devel
yum install lzo-devel zlib-devel gcc gcc-c++

安装Maven

下载：apache-maven-3.0.5-bin.tar.gz
解压：tar -zxvf apache-maven-3.0.5-bin.tar.gz
设置环境变量，打开/etc/profile文件，添加
- export MAVEN_HOME=/opt/apache-maven-3.0.5
- export PATH=$PATH:$MAVEN_HOME/bin
执行命令使之生效：source /etc/profile或者./etc/profile
验证：mvn -v

安装protobuf

解压：tar -zxvf protobuf-2.5.0.tar.gz
进入安装目录，进行配置，执行命令，./configure
安装命令：make & make check & make install
验证：protoc --version

安装findbugs

解压：tar -zxvf findbugs.tar.gz
设置环境变量：
- export export FINDBUGS_HOME=/opt/findbugs-3.0.0
- export PATH=$PATH:$FINDBUGS_HOME/bin
验证命令：findbugs -version

如果出现信息：java lang unsupportedclassversionerror unsupported major minor version 51.0，那么是因为你采用的jdk为open jdk，直接将其卸载，安装Sun公司原装的JDK即可，参考：

http://www.blogjava.net/Jay2009/archive/2009/04/23/267108.html

http://www.cnblogs.com/zhoulf/archive/2013/02/04/2891608.html

如果javac命令无法识别

[ root@centos ~]# javac
Error: could not find libjava.so
Error: could not find Java 2 Runtime Environment.

但是当我这样运行的时候：/usr/lib/jvm/jdk1.7.0_71/bin/javac -version，一切正常，说明可能是旧版jre影响，那么删除open-jre，安装Sun公司Jre

下载了rpm包之后，rpm -ivh jre-7u71-linux-x64.rpm，安装完成之后

[ root@centos ~]# java -version
java version "1.7.0_71"
Java(TM) SE Runtime Environment (build 1.7.0_71-b14)
Java HotSpot(TM) 64-Bit Server VM (build 24.71-b01, mixed mode)
[ root@centos ~]# javac -version
javac 1.7.0_71
[ root@centos ~]#

注意

Hadoop是Java写的，他无法使用Linux预安装的OpenJDK,因此安装hadoop前需要先安装JDK（1.6以上）

另外Hadoop2.2.0存在一个bug

需要修改/opt/hadoop-2.2.0-src/hadoop-common-project/hadoop-auth/pom.xml中的内容（添加黑体部分）：

<dependency>

<groupId>org.mortbay.jetty</groupId>

<artifactId>jetty-util</artifactId>

<scope>test</scope>

</dependency>

<groupId>org.mortbay.jetty</groupId>

<artifactId>jetty</artifactId>

</dependency>

4.4、如何编译

进入到Hadoop源码目录下/opt/hadoop-2.2.0-src，运行红色字体[可选项]：

Building distributions:

Create binary distribution without native code and without documentation:

$ mvn package -Pdist -DskipTests -Dtar

Create binary distribution with native code and with documentation:

$ mvn package -Pdist,native,docs -DskipTests -Dtar

Create source distribution:

$ mvn package -Psrc -DskipTests

Create source and binary distributions with native code and documentation:

$ mvn -e -X package -Pdist,native[,docs,src] -DskipTests -Dtar

Create a local staging version of the website (in /tmp/hadoop-site)

$ mvn clean site; mvn site:stage -DstagingDirectory=/tmp/hadoop-site

4.5、编译之前，可能需要配置MAVEN国内镜像配置

进入安装目录 /opt/modules/apache-maven-3.0.5/conf，编辑 settings.xml 文件

* 修改<mirrors>内容：

<id>nexus-osc</id>

<name>Nexus osc</name>

<url>http://maven.oschina.net/content/groups/public/</url>

</mirror>

* 修改<profiles>内容：

</activation>

<id>nexus</id>

<name>local private nexus</name>

<url>http://maven.oschina.net/content/groups/public/</url>

</releases>

<enabled>false</enabled>

</snapshots>

</repository>

</repositories>

<id>nexus</id>

<name>local private nexus</name>

<url>http://maven.oschina.net/content/groups/public/</url>

</releases>

<enabled>false</enabled>

</snapshots>

</pluginRepository>

</pluginRepositories>

</profile>

复制配置

将该配置文件复制到用户目录，使得每次对maven创建时，都采用该配置

* 查看用户目录【/home/hadoop】是否存在【.m2】文件夹，如没有，则创建

$ cd /home/hadoop

$ mkdir .m2

* 复制文件

$ cp /opt/modules/apache-maven-3.0.5/conf/settings.xml ~/.m2/

4.6、配置DNS

修改： vi /etc/resolv.conf

nameserver 8.8.8.8

nameserver 8.8.4.4

4.7、将Hadoop Project 导入到Eclipse

Importing projects to eclipse

When you import the project to eclipse, install hadoop-maven-plugins at first.

$ cd hadoop-maven-plugins

$ mvn install

Then, generate eclipse project files.

$ mvn eclipse:eclipse -DskipTests

At last, import to eclipse by specifying the root directory of the project via

[File] > [Import] > [Existing Projects into Workspace].

注意：

编译过程中如果出现任何有关jdk或者jre的问题：JAVA_HOME environment variable is not set.

参看

http://www.cnblogs.com/RandyS/p/3909717.html

到 /etc/profile 最后，然后 . /etc/profile或者source /etc/profile使设置生效。

如果出现bash: javac: command not found

那么执行

yum install java-devel即可，这是因为：http://stackoverflow.com/questions/5407703/javac-command-not-found

编译过程中碰到的其他问题： http://blog.csdn.net/xichenguan/article/details/17636905

出现错误：Failed to execute goal org.apache.maven.plugins:maven-antrun-plugin:1.6:run (site) on project hadoop-hdfs: An Ant BuildException has occured: input file /opt/hadoop-2.2.0-src/hadoop-hdfs-project/hadoop-hdfs/target/findbugsXml.xml does not exist

解决办法：

cd ~/hadoop- 2.2 . 0 -src/ mvn clean package -Pdist,native,docs -DskipTests -Dtar // 编译中途出错修正后可从指定点开始继续编译，修改最后一个参数即可。如出现hadoop-hdfs/target/findbugsXml.xml does not exist则从该命令删除docs参数再运行mvn package -Pdist,native -DskipTests -Dtar -rf :hadoop-pipes

build成功之后，进入到/opt/hadoop-2.2.0-src/hadoop-dist/target路径下查看hadoop-2.2.0.tar.gz就是编译完成之后的tar包

出现错误：Could not find goal 'protoc' in plugin org.apache.hadoop:hadoop-maven-plugins:2.2.0 among available

解决办法：在/etc/profile中加入如下内容，之后source /etc/profile

export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/opt/protobuf/lib

export PATH=$PATH:/usr/local/bin

通常建议安装到/usr/local目录下，执行configure时，指定--prefix=/usr/local/protobuf即可，如果出现错误，那么make clean一下，之后再进行操作

我的/etc/profile文件内容：

export MAVEN_HOME=/opt/apache-maven-3.0.5

export PATH=$PATH:$MAVEN_HOME/bin

export JAVA_HOME=/usr/lib/jvm/jdk1.7.0_71/

export JRE_HOME=/usr/lib/jvm/jdk1.7.0_71/jre

export ANT_HOME=/usr/lib/jvm/apache-ant/