code: private int run(String[] args) throws Exception {
      Configuration conf = new Configuration();
      String numMaps =  new GenericOptionsParser(conf, args).getRemainingArgs()[0];
      conf.set(MRJobConfig.NUM_MAPS, numMaps);
      createHdfsFilesystem(conf);
  
      Job job = Job.getInstance(conf, "MapReduceIntegrationChecker");
      job.setJarByClass(MapReduceIntegrationChecker.class);
      job.setMapperClass(CheckerMapper.class);
      job.setCombinerClass(CheckerReducer.class);
      job.setReducerClass(CheckerReducer.class);
      job.setOutputKeyClass(Text.class);
      job.setOutputValueClass(Text.class);
      job.setInputFormatClass(EmptyInputFormat.class);
      FileOutputFormat.setOutputPath(job, mOutputFilePath);
  
      try {
        if (!job.waitForCompletion(true)) {
          return 1;
        }
        Status resultStatus = generateReport();
        return resultStatus.equals(Status.SUCCESS) ? 0
            : (resultStatus.equals(Status.FAIL_TO_FIND_CLASS) ? 2 : 1);
      } finally {
        if (mFileSystem.exists(mOutputFilePath)) {
          mFileSystem.delete(mOutputFilePath, true);
        }
        mFileSystem.close();
      }
    }
docs: Implements MapReduce with Alluxio integration checker.
  
  @return 0 for success, 2 for unable to find Alluxio classes, 1 otherwise