在RetHat中编译YARN，Jdk为1.6.0_23.
1.下载YARN源码包
下载地址：http://mirror.bit.edu.cn/apache/hadoop/common/hadoop-2.0.2-alpha/
（这里下载的版本为2.0.2），下载hadoop-2.0.2-alpha-src.tar.gz.
下载后解压到/home/wyf目录下。
2.安装Maven
YARN使用Maven作为编译工具，以前没用过，这次只好硬着头皮试试了。首先下载Maven软件包，下载地址为：http://labs.mop.com/apache-mirror/maven/maven-3/3.0.4/binaries/apache-maven-3.0.4-bin.tar.gz
下载后解压，设置MAVEN_HOME和PATH变量。设置好后，可以使用mvn-version检查是否安装成功。
3.安装ProtoBuf
为啥YARN编译使用的工具我都没用过，囧。。看来学习的太少了
同样下载，解压。下载地址：http://protobuf.googlecode.com/files/protobuf-2.4.1.tar.bz2
解压： tarjxvf protobuf-2.4.1.tar.bz2
依次执行：./configure， make， sudo makeinstall，这三个命令安装ProtoBuffer。
在执行./configure命令时，可以指定安装目录的前缀（默认安装到/usr/local目录下），指定前缀的方法为（举例）：./configure--prefix=/home/wyf/protobuf，这样的话，protobuf就会安装到/home/wyf/protobuf目录下，安装后在该目录下可以看到三个目录：include、bin、lib。（之前我安装好几次都是只有lib目录，没有其余两个，好像是解压方法不对，最后使用上面所写的解压方法后安装成功）。修改/etc/profile文件，加入exportLD_LIBRARY_PATH=$LD_LIBRARY_PATH:/home/wyf/protobuf/lib
exportPATH=$PATH:/home/wyf/protobuf/bin
最后使用protoc--version检查ProtoBuffer是否安装成功。
4.安装autotool
依然没用过。。。
命令安装：sudo yum install autoconfautomake libtool
5.编译
第一次编译保证网络连接，因为要从网络上下载很多支持的软件包。
若解压后的YARN源码位置为/home/wyf/hadoop-2.0.2-alpha-src，则cd到该目录下，即可开始编译。
编译命令：mvn package -Pdist,native-DskipTests
接下来是漫长的等待。。。。直到出现所有Project均SUCCESS的界面，证明编译完成且成功！
编译成功应显示的信息：
[INFO]------------------------------------------------------------------------
[INFO] ReactorSummary:
[INFO]
[INFO] Apache Hadoop Main................................ SUCCESS [6.256s]
[INFO] Apache Hadoop ProjectPOM ......................... SUCCESS [5.964s]
[INFO] Apache HadoopAnnotations ......................... SUCCESS [4.507s]
[INFO] Apache Hadoop Assemblies.......................... SUCCESS [0.358s]
[INFO] Apache Hadoop ProjectDist POM .................... SUCCESS [4.044s]
[INFO] Apache Hadoop Auth................................ SUCCESS [4.816s]
[INFO] Apache Hadoop AuthExamples ....................... SUCCESS [4.517s]
[INFO] Apache Hadoop Common.............................. SUCCESS [3:37.475s]
[INFO] Apache Hadoop CommonProject ...................... SUCCESS [3.391s]
[INFO] Apache Hadoop HDFS................................ SUCCESS [3:25.417s]
[INFO] Apache Hadoop HttpFS.............................. SUCCESS [45.369s]
[INFO] Apache Hadoop HDFSBookKeeper Journal ............. SUCCESS [19.111s]
[INFO] Apache Hadoop HDFSProject ........................ SUCCESS [0.225s]
[INFO] hadoop-yarn....................................... SUCCESS[1.273s]
[INFO] hadoop-yarn-api................................... SUCCESS[1:49.559s]
[INFO] hadoop-yarn-common................................ SUCCESS [1:14.722s]
[INFO] hadoop-yarn-server................................ SUCCESS [3.524s]
[INFO]hadoop-yarn-server-common ......................... SUCCESS[20.320s]
[INFO]hadoop-yarn-server-nodemanager .................... SUCCESS[22.533s]
[INFO]hadoop-yarn-server-web-proxy ...................... SUCCESS[4.906s]
[INFO]hadoop-yarn-server-resourcemanager ................ SUCCESS[28.781s]
[INFO] hadoop-yarn-server-tests.......................... SUCCESS [2.583s]
[INFO] hadoop-yarn-client................................ SUCCESS [4.943s]
[INFO] hadoop-yarn-applications.......................... SUCCESS [0.149s]
[INFO]hadoop-yarn-applications-distributedshell ......... SUCCESS[3.314s]
[INFO] hadoop-mapreduce-client........................... SUCCESS [0.364s]
[INFO]hadoop-mapreduce-client-core ...................... SUCCESS[47.326s]
[INFO]hadoop-yarn-applications-unmanaged-am-launcher .... SUCCESS[11.138s]
[INFO] hadoop-yarn-site.................................. SUCCESS [0.267s]
[INFO] hadoop-yarn-project............................... SUCCESS [11.935s]
[INFO]hadoop-mapreduce-client-common .................... SUCCESS[47.074s]
[INFO]hadoop-mapreduce-client-shuffle ................... SUCCESS[11.811s]
[INFO]hadoop-mapreduce-client-app ....................... SUCCESS[14.339s]
[INFO]hadoop-mapreduce-client-hs ........................ SUCCESS[7.141s]
[INFO]hadoop-mapreduce-client-jobclient ................. SUCCESS[10.101s]
[INFO] Apache Hadoop MapReduceExamples .................. SUCCESS [7.732s]
[INFO] hadoop-mapreduce.................................. SUCCESS [8.388s]
[INFO] Apache Hadoop MapReduceStreaming ................. SUCCESS [5.928s]
[INFO] Apache HadoopDistributed Copy .................... SUCCESS[15.718s]
[INFO] Apache Hadoop Archives............................ SUCCESS [10.997s]
[INFO] Apache Hadoop Rumen............................... SUCCESS [9.091s]
[INFO] Apache Hadoop Gridmix............................. SUCCESS [5.791s]
[INFO] Apache Hadoop Data Join........................... SUCCESS [3.456s]
[INFO] Apache Hadoop Extras.............................. SUCCESS [4.658s]
[INFO] Apache Hadoop Pipes............................... SUCCESS [3.120s]
[INFO] Apache Hadoop Tools Dist.......................... SUCCESS [2.242s]
[INFO] Apache Hadoop Tools............................... SUCCESS [0.085s]
[INFO] Apache HadoopDistribution ........................ SUCCESS[42.718s]
[INFO] Apache Hadoop Client.............................. SUCCESS [17.661s]
[INFO] Apache HadoopMini-Cluster ........................ SUCCESS [0.736s]
[INFO]------------------------------------------------------------------------
[INFO] BUILDSUCCESS
[INFO]------------------------------------------------------------------------
[INFO] Total time:18:21.523s
[INFO] Finished at: Thu Jan 3115:28:01 CST 2013
6.错误处理
在编译过程中出现了大致两类错误，一是由于网络原因，需要的软件包没有下载下来，导致编译不能继续，编译失败；二是CMake没有安装。
错误1：软件包没下载
在编译的过程中会看到YARN自动download很多需要的软件包，但有时会下载不成功。错误提示大致下面这个样子：
[ERROR] Failed to execute goalorg.apache.maven.plugins:maven-dependency-plugin:2.1:build-classpath(build-classpath) on project hadoop-project: Executionbuild-classpath of goalorg.apache.maven.plugins:maven-dependency-plugin:2.1:build-classpathfailed:
Plugin org.apache.maven.plugins:maven-dependency-plugin:2.1or one of its dependencies could not be resolved: Could nottransfer artifact org.apache.maven.doxia:doxia-core:jar:1.0-alpha-7from/to central (http://repo.maven.apache.org/maven2): GET requestof:org/apache/maven/doxia/doxia-core/1.0-alpha-7/doxia-core-1.0-alpha-7.jarfrom
central failed: Connection reset -> [Help 1]
[ERROR]
[ERROR] To see the full stacktrace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the-X switch to enable full debug logging.
[ERROR]
[ERROR] For more informationabout the errors and possible solutions, please read the followingarticles:
[ERROR] [Help 1]http://cwiki.apache.org/confluence/display/MAVEN/PluginResolutionException
[ERROR]
[ERROR] After correcting theproblems, you can resume the build with the command
[ERROR] mvn-rf :hadoop-project
在编译的过程中出现了好几次ResolutionException(还有DependencyResolutionException）,遇到这个问题，不用修改东西，直接运行命令继续编译就好。YARN会继续从下载失败的软件包开始下载并继续编译。
错误2：CMake没有安装
错误：
[ERROR] Failed to execute goalorg.apache.maven.plugins:maven-antrun-plugin:1.6:run (make) onproject hadoop-common: An Ant BuildException has occured: Executefailed: java.io.IOException: Cannot run program "cmake"
(in directory"/home/wyf/hadoop-2.0.2-alpha-src/hadoop-common-project/hadoop-common/target/native"):java.io.IOException: error=2, No such file or directory -> [Help1]
[ERROR]
[ERROR] To see the full stacktrace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the-X switch to enable full debug logging.
[ERROR]
[ERROR] For more informationabout the errors and possible solutions, please read the followingarticles:
[ERROR] [Help 1]http://cwiki.apache.org/confluence/display/MAVEN/MojoExecutionException
这是安装CMake：
sudo yum installcmake
Complete！后继续编译就可以了。
7.验证
验证编译成功的方法最简单的为使用自己编译的jar文件，运行Hadoop系统。将编译生成的jar文件（一般在target目录下，由于YARN各个部分分的很细，jar包分布在好多目录下的target目录中，需要耐心的找找），替换hadoop-2.0.2-alpha/share/hadoop目录下各个部分对应的jar包，配置hadoop（这里略），在master启动hadoop。
8.疑问
如何只编译YARN中的一部分代码（如YARN模块，或HDFS模块，或MapReduce模块），还没有找到方法。