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介绍
本篇主要会涉及以下内容:
学会编译hadoop2.x源码
编译hadoop源码
为什么要编译
由于hadoop2.x 只支持Linux 32位，针对Linux 64位没有 native lib 库的支持，必须手动编译。所以下载的二进制包，当启动hadoop的时候，会出现如下警告：
WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform… using builtin-java classes where applicable
如何编译
在64位Linux下编译
首先打开hadoop2.x源码下的build.txt 查看编译说明：
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 Javadocs)
- 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)编译选项
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 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编译前安装依赖包
yum install autoconf automake libtool cmake
yum install ncurses-devel
yum install openssl-devel
yum install lzo-devel zlib-devel gcc gcc-c++查软件包是否没有装上：
rpm -qa | grep autoconf编译前安装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：
export MAVEN_HOME = /usr/local/maven
export PATH=$PATH:$MAVEN_HOME/bin执行命令：source /etc/profile或者 . /etc/profile
验证：mvn -v
编译前安装protobuf
下载：protobuf-2.5.0.tar.gz
解压:
tar -zxvf protobuf-2.5.0.tar.gz编译安装：
进入安装目录，进行配置，执行命令：
./configure
安装命令：
make & make install
编译前安装findbugs
下载：findbugs-3.0.0.tar.gz
解压:
tar -zxvf findbugs-3.0.0.tar.gz设置环境变量：
export FINDBUGS_HOME = /usr/local/findbugs
export PATH=$PATH:$FINDBUGS_HOME/bin执行命令：source /etc/profile或者 . /etc/profile
验证：findbugs -version
MAVEN国内镜像配置
1、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：
<mirror>
<id>nexus-osc</id>
<mirrorOf>*</mirrorOf>
<name>Nexus osc</name>
<url>http://maven.oschina.net/content/groups/public/</url>
</mirror> 修改<profiles>内容：
<profile>
<id>jdk-1.8</id>
<activation>
<jdk>1.8</jdk>
</activation>
<repositories>
<repository>
<id>nexus</id>
<name>local private nexus</name>
<url>http://maven.oschina.net/content/groups/public/</url>
<releases>
<enabled>true</enabled>
</releases>
<snapshots>
<enabled>false</enabled>
</snapshots>
</repository>
</repositories>
<pluginRepositories>
<pluginRepository>
<id>nexus</id>
<name>local private nexus</name>
<url>http://maven.oschina.net/content/groups/public/</url>
<releases>
<enabled>true</enabled>
</releases>
<snapshots>
<enabled>false</enabled>
</snapshots>
</pluginRepository>
</pluginRepositories>
</profile> 2、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 ~/.m2/3.配置DNS
修改： vi /etc/resolv.conf
nameserver 8.8.8.8
nameserver 8.8.4.4
开始编译
Hadoop2.2 .0 有bug ，编译 之前需要先 fix bug
下载 hadoop2.x源码
解压
源码打patch,编辑目录$HADOOP_SRC_HOME/hadoop-common-project/hadoop-auth中的文件pom.xml,在第55行下增加以下内容：
<dependency>
<groupId>org.mortbay.jetty</groupId>
<artfactId>jetty-util<artfactId>
<scope>test</scope>
</dependency>这里编译的是hadoop2.7.1版本
mvn package –DskipTests –Pdist,native,docs -Dtar
报错
1.编译出错的话，如下有解决方式：
export MAVEN_OPTS=”-Xms256m -Xmx512m”
2.报错：java heap size
把虚拟机内存调大，然后重启虚拟机，重新编译
3.报错还有可能是maven下载jar的时候，网络出现问题，重新编译
CentOS编译成功界面：
上面是Cetos下的编译，ubuntu编译：
首先要安装的软件：
JDk
Maven
Findbugs
G++
Protobuf
Openssl
CMake
Ant
Ubuntu编译成功界面：
