lzo的安装及在hadoop中的配置
一、前提
1、gcc的安装：yum install lib* glibc* gcc* 如果lzo编译出错时可能需要安装
2、ant的安装：安装略，最好1.8.2及以上版本，并设置好环境变量 在第三步需要用到ant
二、lzo的安装
wget http://www.oberhumer.com/opensource/lzo/download/lzo-2.06.tar.gz
./configure --enable-shared
make
make install
#编辑/etc/ld.so.conf，加入/usr/local/lib/后，执行/sbin/ldconfig
或者cp /usr/local/lib/liblzo2.* /usr/lib64/
三、lzo编码/解码器的安装：
wget https://download.github.com/kevinweil-hadoop-lzo-2ad6654.tar.gz
tar-zxvf kevinweil-hadoop-lzo-2ad6654.tar.gz
cd kevinweil-hadoop-lzo-2ad6654
ant compile-native tar
#将本地库以及Jar包拷贝到hadoop对应的目录下，并分发到各节点上
cp lib/native/Linux-amd64-64/* /opt/hadoop/hadoop/lib/native/Linux-amd64-64/ #32位系统则是32位的路径目录
cp hadoop-lzo-0.4.10.jar .../hadoop/lib/
第二中安装方式：
https://github.com/twitter/hadoop-lzo/tree/release-0.4.19 在twitter上找到安装包
解压并修改pom文件，主要是hadoop的版本
然后执行mvn clean package-Dmaven.test.skip=true 搞定。
四、hadoop配置
vi core-site.xml
<property> <name>io.compression.codecs</name> <value>org.apache.hadoop.io.compress.GzipCodec,org.apache.hadoop.io.compress.DefaultCodec,com.hadoop.compression.lzo.LzoCodec,com.hadoop.compression.lzo.LzopCodec,org.apache.hadoop.io.compress.BZip2Codec</value> </property> <property> <name>io.compression.codec.lzo.class</name> <value>com.hadoop.compression.lzo.LzoCodec</value> </property>
vi mapred-site.xml
<property> <name>mapred.compress.map.output</name> <value>true</value> </property> <property> <name>mapred.map.output.compression.codec</name> <value>com.hadoop.compression.lzo.LzoCodec</value> </property>
以上在hadoop-0.20.203.0中测试通过，但在204.0和205.0中会出现如下问题：
hadoop-0.20.204.0中报错：
2012-01-06 12:09:30,475 ERROR lzo.GPLNativeCodeLoader (GPLNativeCodeLoader.java:<clinit>(36)) - Could not load native gpl library
java.lang.UnsatisfiedLinkError: no gplcompression in java.library.path
at java.lang.ClassLoader.loadLibrary(ClassLoader.java:1734)
at java.lang.Runtime.loadLibrary0(Runtime.java:823)
at java.lang.System.loadLibrary(System.java:1028)
at com.hadoop.compression.lzo.GPLNativeCodeLoader.<clinit>(GPLNativeCodeLoader.java:32)
at com.hadoop.compression.lzo.LzoCodec.<clinit>(LzoCodec.java:67)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:247)
at org.apache.hadoop.conf.Configuration.getClassByName(Configuration.java:819)
at org.apache.hadoop.hive.ql.io.RCFile$Reader.init(RCFile.java:1109)
at org.apache.hadoop.hive.ql.io.RCFile$Reader.<init>(RCFile.java:983)
at org.apache.hadoop.hive.ql.io.RCFile$Reader.<init>(RCFile.java:964)
at org.apache.hadoop.hive.ql.io.RCFileRecordReader.<init>(RCFileRecordReader.java:52)
at org.apache.hadoop.hive.ql.io.RCFileInputFormat.getRecordReader(RCFileInputFormat.java:57)
at org.apache.hadoop.hive.ql.exec.FetchOperator.getRecordReader(FetchOperator.java:306)
at org.apache.hadoop.hive.ql.exec.FetchOperator.getNextRow(FetchOperator.java:320)
at org.apache.hadoop.hive.ql.exec.FetchTask.fetch(FetchTask.java:133)
at org.apache.hadoop.hive.ql.Driver.getResults(Driver.java:1114)
at org.apache.hadoop.hive.cli.CliDriver.processCmd(CliDriver.java:187)
at org.apache.hadoop.hive.cli.CliDriver.processLine(CliDriver.java:241)
at org.apache.hadoop.hive.cli.CliDriver.main(CliDriver.java:456)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.apache.hadoop.util.RunJar.main(RunJar.java:156)
2012-01-06 12:09:30,476 ERROR lzo.LzoCodec (LzoCodec.java:<clinit>(77)) - Cannot load native-lzo without native-hadoop
2012-01-06 12:09:30,478 ERROR CliDriver (SessionState.java:printError(343)) - Failed with exception java.io.IOException:java.lang.RuntimeException: native-lzo library not available
java.io.IOException: java.lang.RuntimeException: native-lzo library not available
at org.apache.hadoop.hive.ql.exec.FetchOperator.getNextRow(FetchOperator.java:341)
at org.apache.hadoop.hive.ql.exec.FetchTask.fetch(FetchTask.java:133)
at org.apache.hadoop.hive.ql.Driver.getResults(Driver.java:1114)
at org.apache.hadoop.hive.cli.CliDriver.processCmd(CliDriver.java:187)
at org.apache.hadoop.hive.cli.CliDriver.processLine(CliDriver.java:241)
at org.apache.hadoop.hive.cli.CliDriver.main(CliDriver.java:456)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.apache.hadoop.util.RunJar.main(RunJar.java:156)
Caused by: java.lang.RuntimeException: native-lzo library not available
at com.hadoop.compression.lzo.LzoCodec.getDecompressorType(LzoCodec.java:180)
at org.apache.hadoop.hive.ql.io.CodecPool.getDecompressor(CodecPool.java:122)
at org.apache.hadoop.hive.ql.io.RCFile$Reader.init(RCFile.java:1117)
at org.apache.hadoop.hive.ql.io.RCFile$Reader.<init>(RCFile.java:983)
at org.apache.hadoop.hive.ql.io.RCFile$Reader.<init>(RCFile.java:964)
at org.apache.hadoop.hive.ql.io.RCFileRecordReader.<init>(RCFileRecordReader.java:52)
at org.apache.hadoop.hive.ql.io.RCFileInputFormat.getRecordReader(RCFileInputFormat.java:57)
at org.apache.hadoop.hive.ql.exec.FetchOperator.getRecordReader(FetchOperator.java:306)
at org.apache.hadoop.hive.ql.exec.FetchOperator.getNextRow(FetchOperator.java:320)
... 10 more解决办法：在$hadoop_home/bin/hadoop文件中增加如下一行即可JAVA_LIBRARY_PATH=$hadoop_home/lib/native/Linux-amd64-64
在hadoop-0.20.205版本中处了该错误外，还有一个错误，就是找不到lzo的jar包，这是因为他们家在classpath的方法有了变更，默认不会把$hadoop_home/lib目录下的所有jar包都加载，所以在/conf/hadoop-env.sh中增加如下代码即可解决：export HADOOP_CLASSPATH=$HADOOP_CLASSPATH:$hadoop_home/lib/hadoop-lzo.jar