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{{{
#!text
以下練習，請連線至 hdp01.3du.me 操作。底下的 userXX 等於您的用戶名稱。
以下練習，請連線至 hdp02.3du.me 操作。底下的 userXX 等於您的用戶名稱。
以下練習，請連線至 hdp03.3du.me 操作。底下的 userXX 等於您的用戶名稱。
以下練習，請連線至 hdp04.3du.me 操作。底下的 userXX 等於您的用戶名稱。
}}}

= 實作八 Lab 8 =

{{{
#!html
<div style="text-align: center;"><big style="font-weight: bold;"><big>HDFS、MapReduce 與 Hadoop Streaming 觀念驗證<br/>Running Hadoop Streaming with HDFS and MapReduce</big></big></div>
}}}

== 準備輸入資料集 Input Dataset ==

 * 首先準備輸入，包含兩部份：(1) 供 Velvet 計算的 *.fa 檔案，這裡為了方便示範起見，採用 test_long.fa 當範本，並複製 99 份不同檔名，當輸入 (2) 供 Mapper 運算的輸入檔案（內含 HDFS 的檔名路徑）
{{{
~$ echo "test" > test_long.fa
~$ for ((i=1;i<100;i++)); do hadoop fs -put test_long.fa input-$i.fa; done
~$ for ((i=1;i<20;i++)); do echo /user/$(whoami)/input-$i.fa; done > split-01.txt
~$ for ((i=20;i<40;i++)); do echo /user/$(whoami)/input-$i.fa; done > split-02.txt
~$ for ((i=40;i<60;i++)); do echo /user/$(whoami)/input-$i.fa; done > split-03.txt
~$ for ((i=60;i<80;i++)); do echo /user/$(whoami)/input-$i.fa; done > split-04.txt
~$ for ((i=80;i<100;i++)); do echo /user/$(whoami)/input-$i.fa; done > split-05.txt
~$ hadoop fs -mkdir lab10_input
~$ hadoop fs -put split-0* lab10_input
}}}
 * 檢查輸入檔案
{{{
~$ hadoop fs -ls
~$ hadoop fs -ls lab10_input
}}}

== 觀察 Hadoop Streaming 執行身份與工作目錄 ==

 * 撰寫 testmapper.sh
{{{
#!sh
#!/bin/bash

id="h998"
mkdir -p /tmp/$id
host=`hostname`
pwd=`pwd`
uid=`whoami`

while read line; do 
  input=$line
  filename=`basename $input`
  echo "$uid@$host:$pwd> hadoop fs -get $input /tmp/$id/$filename"
  echo "$uid@$host:$pwd> velveth output-$filename 17 -fasta -short /tmp/$id/$filename"
  echo "$uid@$host:$pwd> hadoop fs -put output-$filename ."
done
rm -rf /tmp/$id
}}}
 * 接著，讓我們在本地端先驗證一下 testmapper.sh 的運作
{{{
~$ head -n 2 split-01.txt > split-00.txt
~$ cat > testmapper.sh << EOF
#!/bin/bash

id="`whoami`"
mkdir -p /tmp/\$id
host=\`hostname\`
pwd=\`pwd\`
uid=\`whoami\`

while read line; do 
  input=\$line
  filename=\`basename \$input\`
  echo "\$uid@\$host:\$pwd> hadoop fs -get \$input /tmp/\$id/\$filename"
  echo "\$uid@\$host:\$pwd> velveth output-\$filename 17 -fasta -short /tmp/\$id/\$filename"
  echo "\$uid@\$host:\$pwd> hadoop fs -put output-\$filename ."
done
rm -rf /tmp/\$id
EOF
~$ chmod a+x testmapper.sh
~$ cat split-00.txt | ./testmapper.sh 
user00@hdp01.3du.me:/home/user00> hadoop fs -get /user/user00/input-1.fa /tmp/user00/input-1.fa
user00@hdp01.3du.me:/home/user00> velveth output-input-1.fa 17 -fasta -short /tmp/user00/input-1.fa
user00@hdp01.3du.me:/home/user00> hadoop fs -put output-input-1.fa .
user00@hdp01.3du.me:/home/user00> hadoop fs -get /user/user00/input-2.fa /tmp/user00/input-2.fa
user00@hdp01.3du.me:/home/user00> velveth output-input-2.fa 17 -fasta -short /tmp/user00/input-2.fa
user00@hdp01.3du.me:/home/user00> hadoop fs -put output-input-2.fa .
}}}
 * 讓我們用 Hadoop Streaming 的方式來執行 testmapper.sh
{{{
~$ hadoop jar hadoop-streaming.jar -input lab10_input -output lab10_out1 -mapper testmapper.sh -file testmapper.sh -numReduceTasks 0
}}}
 * 觀察 lab10_out1 的結果，看與本機執行有何不同呢？
{{{
~$ hadoop fs -cat /user/$(whoami)/lab10_out1/part-00000 | head
root@hdp05.3du.me:/opt/hadoop/var/hadoop-root/mapred/local/taskTracker/user00/jobcache/job_201411281523_0038/attempt_201411281523_0038_m_000000_0/work> hadoop fs -get /user/user00/input-20.fa /tmp/user00/input-20.fa
root@hdp05.3du.me:/opt/hadoop/var/hadoop-root/mapred/local/taskTracker/user00/jobcache/job_201411281523_0038/attempt_201411281523_0038_m_000000_0/work> velveth output-input-20.fa 17 -fasta -short /tmp/user00/input-20.fa
root@hdp05.3du.me:/opt/hadoop/var/hadoop-root/mapred/local/taskTracker/user00/jobcache/job_201411281523_0038/attempt_201411281523_0038_m_000000_0/work> hadoop fs -put output-input-20.fa .
root@hdp05.3du.me:/opt/hadoop/var/hadoop-root/mapred/local/taskTracker/user00/jobcache/job_201411281523_0038/attempt_201411281523_0038_m_000000_0/work> hadoop fs -get /user/user00/input-21.fa /tmp/user00/input-21.fa
root@hdp05.3du.me:/opt/hadoop/var/hadoop-root/mapred/local/taskTracker/user00/jobcache/job_201411281523_0038/attempt_201411281523_0038_m_000000_0/work> velveth output-input-21.fa 17 -fasta -short /tmp/user00/input-21.fa
root@hdp05.3du.me:/opt/hadoop/var/hadoop-root/mapred/local/taskTracker/user00/jobcache/job_201411281523_0038/attempt_201411281523_0038_m_000000_0/work> hadoop fs -put output-input-21.fa .
root@hdp05.3du.me:/opt/hadoop/var/hadoop-root/mapred/local/taskTracker/user00/jobcache/job_201411281523_0038/attempt_201411281523_0038_m_000000_0/work> hadoop fs -get /user/user00/input-22.fa /tmp/user00/input-22.fa
root@hdp05.3du.me:/opt/hadoop/var/hadoop-root/mapred/local/taskTracker/user00/jobcache/job_201411281523_0038/attempt_201411281523_0038_m_000000_0/work> velveth output-input-22.fa 17 -fasta -short /tmp/user00/input-22.fa
root@hdp05.3du.me:/opt/hadoop/var/hadoop-root/mapred/local/taskTracker/user00/jobcache/job_201411281523_0038/attempt_201411281523_0038_m_000000_0/work> hadoop fs -put output-input-22.fa .
}}}

== 實作透過 Hadoop Streaming 執行 99 組 velvet 運算 ==

 * 撰寫 mapper.sh
{{{
#!sh
#!/bin/bash

id="h998"
mkdir -p /tmp/$id
host=`hostname`
pwd=`pwd`
uid=`whoami`

while read line; do 
  input=$line
  filename=`basename $input`
  echo "$uid@$host> hadoop fs -get $input /tmp/$id/$filename"
  hadoop fs -get $input /tmp/$id/$filename
  echo "$uid@$host> velveth output-$filename 17 -fasta -short /tmp/$id/$filename"
  velveth output-$filename 17 -fasta -short /tmp/$id/$filename
  echo "$uid@$host> hadoop fs -put output-$filename /user/$id/."
  hadoop fs -put output-$filename /user/$id/.
  hadoop fs -chown $id /user/$id/output-$filename
done
rm -rf /tmp/$id
}}}
 * 於本機測試 mapper.sh
{{{
~$ cat > mapper.sh << EOF
#!/bin/bash

id="`whoami`"
mkdir -p /tmp/\$id
host=\`hostname\`
pwd=\`pwd\`
uid=\`whoami\`

while read line; do 
  input=\$line
  filename=\`basename \$input\`
  echo "\$uid@\$host> hadoop fs -get \$input /tmp/\$id/\$filename"
  hadoop fs -get \$input /tmp/\$id/\$filename
  echo "\$uid@\$host> velveth output-\$filename 17 -fasta -short /tmp/\$id/\$filename"
  velveth output-\$filename 17 -fasta -short /tmp/\$id/\$filename
  echo "\$uid@\$host> hadoop fs -put output-\$filename /user/\$id/."
  hadoop fs -put output-\$filename /user/\$id/.
  hadoop fs -chown \$id /user/\$id/output-\$filename
done
rm -rf /tmp/\$id
EOF
~$ chmod a+x mapper.sh
~$ cat split-00.txt | ./mapper.sh 
~$ hadoop fs -rmr output-*
~$ rm -rf output-sample-*
}}}
 * 接著用 hadoop streaming 來執行
{{{
~$ hadoop jar hadoop-streaming.jar -input lab10_input -output lab10_out2 -mapper mapper.sh -file mapper.sh -numReduceTasks 0
}}}