drozturk / hadoopwordcountsample

HadoopWordCountSample

Usage

Create 2 sample data files: echo "A long time ago in a galaxy far far away" > /home/cloudera/testfile1
echo "Another episode of Star Wars" > /home/cloudera/testfile2

Assuming username is cloudera for following commands: Create a directory on the HDFS file system hdfs dfs -mkdir /user/cloudera/input

Copy the files from local filesystem to the HDFS filesystem:

hdfs dfs -put /home/cloudera/testfile1 /user/cloudera/input

hdfs dfs -put /home/cloudera/testfile2 /user/cloudera/input

Run the Hadoop WordCount example with the input and output specified. (If your run failed first cleadn output: hdfs dfs -rmdir output_new)

hadoop jar /usr/lib/hadoop-mapreduce/hadoop-streaming.jar \
-input /user/cloudera/input \   
-output /user/cloudera/output_new \   
-mapper /home/cloudera/HadoopWordCountSample/wordcount_mapper.py \   
-reducer /home/cloudera/HadoopWordCountSample/wordcount_reducer.py

see output

hdfs dfs -cat /user/cloudera/output_new/part-00000

To see the result of mappers, assign 0 reducers:

hadoop jar /usr/lib/hadoop-mapreduce/hadoop-streaming.jar \
   -input /user/cloudera/input \
   -output /user/cloudera/output_new_0 \
   -mapper /home/cloudera/HadoopWordCountSample/wordcount_mapper.py \
   -reducer /home/cloudera/HadoopWordCountSample/wordcount_reducer.py \
   -numReduceTasks 0

hdfs dfs -getmerge /user/cloudera/output_new_0/* wordcount_num0_output.txt