Build instructions for Hadoop (Hadoop 编译安装,参考hadoop源码包中BUILDING.txt文档)
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Requirements（编译需求，需要满足以下条件才能编译成功）:
* 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)
* Zlib devel (if compiling native code)
* openssl devel ( if compiling native hadoop-pipes )
* Internet connection for first build (to fetch all Maven and Hadoop dependencies)
安装以上依赖条件：
yum groupinstall “Development tools”
yum -y install cmake zlib openssl gcc zlib-devel openssl-devel make
tar -zxvf protobuf-2.5.0.tar.gz
make && make install
protoc --version
安装maven（apache-maven-3.0.5-bin.zip）
解压、配置环境变量-略
[root@chavin ~]# mvn -version
Apache Maven 3.0.5 (r01de14724cdef164cd33c7c8c2fe155faf9602da; 2013-02-19 21:51:28+0800)
Maven home: /usr/local/maven305
Java version: 1.7.0_67, vendor: Oracle Corporation
Java home: /usr/java/jdk1.7.0_67/jre
Default locale: en_US, platform encoding: UTF-8
OS name: "linux", version: "2.6.32-431.el6.x86_64", arch: "amd64", family: "unix"
配置软件库：
[root@chavin ~]# ll /home/hadoop/.m2/
total 16
drwxrwxr-x. 56 hadoop hadoop 4096 Mar 3 20:13 repository
-rw-r--r--. 1 hadoop hadoop 10224 Mar 3 20:13 settings.xml
其中repository通过tar包repository.tar.gz解压得到。
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
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编译选项：
Build options:
* Use -Pnative to compile/bundle native code
* Use -Pdocs to generate & bundle the documentation in the distribution (using -Pdist)
* Use -Psrc to create a project source TAR.GZ
* Use -Dtar to create a TAR with the distribution (using -Pdist)
Snappy build options:
Snappy is a compression library that can be utilized by the native code.
It is currently an optional component, meaning that Hadoop can be built with
or without this dependency.
* Use -Drequire.snappy to fail the build if libsnappy.so is not found.
If this option is not specified and the snappy library is missing,
we silently build a version of libhadoop.so that cannot make use of snappy.
This option is recommended if you plan on making use of snappy and want
to get more repeatable builds.
* Use -Dsnappy.prefix to specify a nonstandard location for the libsnappy
header files and library files. You do not need this option if you have
installed snappy using a package manager.
* Use -Dsnappy.lib to specify a nonstandard location for the libsnappy library
files. Similarly to snappy.prefix, you do not need this option if you have
installed snappy using a package manager.
* Use -Dbundle.snappy to copy the contents of the snappy.lib directory into
the final tar file. This option requires that -Dsnappy.lib is also given,
and it ignores the -Dsnappy.prefix option.
OpenSSL build options:
OpenSSL includes a crypto library that can be utilized by the native code.
It is currently an optional component, meaning that Hadoop can be built with
or without this dependency.
* Use -Drequire.openssl to fail the build if libcrypto.so is not found.
If this option is not specified and the openssl library is missing,
we silently build a version of libhadoop.so that cannot make use of
openssl. This option is recommended if you plan on making use of openssl
and want to get more repeatable builds.
* Use -Dopenssl.prefix to specify a nonstandard location for the libcrypto
header files and library files. You do not need this option if you have
installed openssl using a package manager.
* Use -Dopenssl.lib to specify a nonstandard location for the libcrypto library
files. Similarly to openssl.prefix, you do not need this option if you have
installed openssl using a package manager.
* Use -Dbundle.openssl to copy the contents of the openssl.lib directory into
the final tar file. This option requires that -Dopenssl.lib is also given,
and it ignores the -Dopenssl.prefix option.
Tests options:
* Use -DskipTests to skip tests when running the following Maven goals:
'package', 'install', 'deploy' or 'verify'
* -Dtest=<TESTCLASSNAME>,<TESTCLASSNAME#METHODNAME>,....
* -Dtest.exclude=<TESTCLASSNAME>
* -Dtest.exclude.pattern=**/<TESTCLASSNAME1>.java,**/<TESTCLASSNAME2>.java
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编译方法：
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
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Handling out of memory errors in builds（编译过程中可能遇到的问题）
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If the build process fails with an out of memory error, you should be able to fix
it by increasing the memory used by maven -which can be done via the environment
variable MAVEN_OPTS.
Here is an example setting to allocate between 256 and 512 MB of heap space to
Maven
export MAVEN_OPTS="-Xms256m -Xmx512m"
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编译命令：mvn package -Pdist,native -DskipTests -Dtar
mvn package -DskipTests -Dtar -Dsnappy.lib=/usr/lib64/ -Dbundle.snappy