Hadoop Streaming 实战: bash脚本
2011-10-10 17:53
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streaming支持使用脚本作为map、reduce程序。以下介绍一个实现分布式的计算所有文件的总行数的程序
1. 待检索的数据放入hdfs
$ hadoop fs -put localfile /user/hadoop/hadoopfile
2. 编写map、reduce脚本,记得给脚本加可执行权限。
mapper.sh
view
plain
#!/bin/sh
wc –l
reducer.sh
view
plain
#!/bin/sh
sum=0
while read i
do
sum=$((sum+i))
done
echo $sum
3. 运行:
hadoop jar /home/hadoop/hadoop/contrib/streaming/hadoop-0.20.2-streaming.jar -input data/pg4300.txt -output out13 -mapper ./mapper.sh -reducer ./reducer.sh -file mapper.sh -file reducer.sh -jobconf mapre.job.name="grep-test" -jobconf stream.non.zero.exit.is.failure=false
-jobconf mapred.reduce.tasks=1
说明:
-input /user/hadoop/hadoopfile : 待处理文件目录
-output /user/hadoop/result :处理结果存放目录
-file :分发mapper.sh和reducer.sh到hdfs中
-jobconf mapred.reduce.tasks=1 : reduce任务数
3. 查看结果:
$ hadoop fs –cat /user/hadoop/result/part-00000
1. 待检索的数据放入hdfs
$ hadoop fs -put localfile /user/hadoop/hadoopfile
2. 编写map、reduce脚本,记得给脚本加可执行权限。
mapper.sh
view
plain
#!/bin/sh
wc –l
reducer.sh
view
plain
#!/bin/sh
sum=0
while read i
do
sum=$((sum+i))
done
echo $sum
3. 运行:
hadoop jar /home/hadoop/hadoop/contrib/streaming/hadoop-0.20.2-streaming.jar -input data/pg4300.txt -output out13 -mapper ./mapper.sh -reducer ./reducer.sh -file mapper.sh -file reducer.sh -jobconf mapre.job.name="grep-test" -jobconf stream.non.zero.exit.is.failure=false
-jobconf mapred.reduce.tasks=1
说明:
-input /user/hadoop/hadoopfile : 待处理文件目录
-output /user/hadoop/result :处理结果存放目录
-file :分发mapper.sh和reducer.sh到hdfs中
-jobconf mapred.reduce.tasks=1 : reduce任务数
3. 查看结果:
$ hadoop fs –cat /user/hadoop/result/part-00000
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