I have created a map method that reads the map output of the wordcount example [1]. This example is away from using the IdentityMapper.class
that MapReduce offers, but this is the only way that I have found to make a working IdentityMapper
for the Wordcount. The only problem is that this Mapper is taking much more time than I wanted. I am starting to think that maybe I am doing some redundant stuff. Any help to improve my WordCountIdentityMapper
code?
[1] Identity mapper
public class WordCountIdentityMapper extends MyMapper<LongWritable, Text, Text, IntWritable> {
private Text word = new Text();
public void map(LongWritable key, Text value, Context context
) throws IOException, InterruptedException {
StringTokenizer itr = new StringTokenizer(value.toString());
word.set(itr.nextToken());
Integer val = Integer.valueOf(itr.nextToken());
context.write(word, new IntWritable(val));
}
public void run(Context context) throws IOException, InterruptedException {
while (context.nextKeyValue()) {
map(context.getCurrentKey(), context.getCurrentValue(), context);
}
}
}
[2] Map class that generated the mapoutput
public static class MyMap extends Mapper<LongWritable, Text, Text, IntWritable> {
private final static IntWritable one = new IntWritable(1);
private Text word = new Text();
public void map(LongWritable key, Text value, Context context
) throws IOException, InterruptedException {
StringTokenizer itr = new StringTokenizer(value.toString());
while (itr.hasMoreTokens()) {
word.set(itr.nextToken());
context.write(word, one);
}
}
public void run(Context context) throws IOException, InterruptedException {
try {
while (context.nextKeyValue()) {
map(context.getCurrentKey(), context.getCurrentValue(), context);
}
} finally {
cleanup(context);
}
}
}
Thanks,
The solution to this is replace the StringTokenizer
by the indexOf()
method. It works much better. I get better performance.