DistSum.java 文件源码

/** {@inheritDoc} */
@Override
public void init(Job job) {
  // setup mapper
  job.setMapperClass(PartitionMapper.class);
  job.setMapOutputKeyClass(IntWritable.class);
  job.setMapOutputValueClass(SummationWritable.class);

  // setup partitioner
  job.setPartitionerClass(IndexPartitioner.class);

  // setup reducer
  job.setReducerClass(SummingReducer.class);
  job.setOutputKeyClass(NullWritable.class);
  job.setOutputValueClass(TaskResult.class);
  final Configuration conf = job.getConfiguration();
  final int nParts = conf.getInt(N_PARTS, 1);
  job.setNumReduceTasks(nParts);

  // setup input
  job.setInputFormatClass(SummationInputFormat.class);
}