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#!html
<div style="text-align: center;"><big
 style="font-weight: bold;"><big><big>實做四: Hadoop 程式編譯</big></big></big></div>
}}}
[[PageOutline]]

 = 練習 1 : Word Count 初級版 =

 * 上傳內容到hdfs內

{{{
$ cd /opt/hadoop
$ mkdir lab4_input
$ echo "I like NCHC Cloud Course." > lab4_input/input1
$ echo "I like nchc Cloud Course, and we enjoy this course." > lab4_input/input2
$ bin/hadoop fs -put lab4_input lab4_input
$ bin/hadoop fs -ls lab4_input
}}}

 * 下載 [attachment:wiki:jazz/Hadoop_Lab6:WordCount.java?format=raw WordCount.java] 並存到/opt/hadoop;
{{{
$ wget http://trac.nchc.org.tw/cloud/attachment/wiki/jazz/Hadoop_Lab6/WordCount.java?format=raw
$ mv WordCount.java\?format\=raw WordCount.java
}}}

 * 運作程式

{{{
$ mkdir MyJava
$ javac -classpath hadoop-*-core.jar -d MyJava WordCount.java
$ jar -cvf wordcount.jar -C MyJava .
$ bin/hadoop jar wordcount.jar WordCount lab4_input/ lab4_out1/
$ bin/hadoop fs -cat lab4_out1/part-00000
}}}

 * lab4_out1 執行結果 
{{{
#!text
Cloud	2
Course,	1
Course.	1
I	2
NCHC	1
and	1
course.	1
enjoy	1
like	2
nchc	1
this	1
we	1
}}}
-----

 = 練習 2 : Word Count 進階版 =

{{{
$ echo "\." >pattern.txt && echo "\," >>pattern.txt
$ bin/hadoop fs -put pattern.txt ./
$ mkdir MyJava2
}}}


 * 下載 [attachment:wiki:jazz/Hadoop_Lab6:WordCount2.java?format=raw WordCount2.java] 並存到/opt/hadoop;
{{{
$ wget http://trac.nchc.org.tw/cloud/attachment/wiki/jazz/Hadoop_Lab6/WordCount2.java?format=raw
$ mv WordCount2.java\?format\=raw WordCount2.java
}}}

{{{
$ javac -classpath hadoop-*-core.jar -d MyJava2 WordCount2.java
$ jar -cvf wordcount2.jar -C MyJava2 .
$ bin/hadoop jar wordcount2.jar WordCount2 lab4_input lab4_out2 -skip pattern.txt
$ bin/hadoop fs -cat lab4_out2/part-00000
}}}

 * lab4_out2 執行結果
{{{
#!text
Cloud	2
Course	2
I	2
NCHC	1
and	1
course	1
enjoy	1
like	2
nchc	1
this	1
we	1
}}}

{{{
$ bin/hadoop jar wordcount2.jar WordCount2 -Dwordcount.case.sensitive=false lab4_input lab4_out3 -skip pattern.txt
$ bin/hadoop fs -cat lab4_out3/part-00000
}}}

 * lab4_out3 執行結果
{{{
#!text
and	1
cloud	2
course	3
enjoy	1
i	2
like	2
nchc	2
this	1
we	1
}}}

= Hadoop 運算時出錯 = 

 * 可到 /opt/hadoop/logs 內看日誌檔
 * 用瀏覽器打開 [http://localhost:50070/logs/ ] 或 [http://localhost:50030/logs/] 皆可

日誌名稱的格式為
 ||hadoop||-||使用者||-||工作身份||-||主機||.||副檔名|| 
因此，
 * 運作於 pc121 主機上的 namenode 的日誌為 
   * hadoop-hadooper-namenode-pc121.log 
 * 運作於 pc122 主機上的 datanode 的日誌為 
   * hadoop-hadooper-datanode-pc122.log 
 * 運作於 pc123 主機上的 jobtracker 的日誌為 
   * hadoop-hadooper-jobtracker-pc123.log 
 * 運作於 pc124 主機上的 tasktracker 的日誌為 
   * hadoop-hadooper-tasktracker-pc124.log