An issue in MapReduce Tutorial

[Gino Gu01 <Gi...@infosys.com>]

There is one bug in WordCount v2.0 which is part of MapReduce Tutorial.
How to reproduce:

Run the application:

$ bin/hadoop jar wc.jar WordCount2 /user/joe/wordcount/input /user/joe/wordcount/output
It will throw Null Pointer Exception during map phase.

Reason:
Below highlighted line set the default value of wordcount.skip.patterns to true.
But in the arguments we didn't pass the any patterns file, so the line for (URI patternsURI : patternsURIs) throws exception.
    public void setup(Context context) throws IOException,
        InterruptedException {
      conf = context.getConfiguration();
      caseSensitive = conf.getBoolean("wordcount.case.sensitive", true);
      if (conf.getBoolean("wordcount.skip.patterns", true)) {
        URI[] patternsURIs = Job.getInstance(conf).getCacheFiles();
        for (URI patternsURI : patternsURIs) {
          Path patternsPath = new Path(patternsURI.getPath());
          String patternsFileName = patternsPath.getName().toString();
          parseSkipFile(patternsFileName);
        }
      }
}

How to fix it:
Change above highlighted line to
conf.getBoolean("wordcount.skip.patterns", false))


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