我一直在ClouderaVM4.7中使用Hadoop2.0。我正试着打印出这本书中最神秘的5个单词 cleanup 文档中描述如何使用的方法。但根本没人打电话。

public static class Reduce extends MapReduceBase implements
        Reducer<Text, IntWritable, Text, IntWritable> {

    private java.util.Map<String, Integer> top5 = new HashMap<String, Integer>(5);

    public void reduce(Text key, Iterator<IntWritable> values,
            OutputCollector<Text, IntWritable> output, Reporter reporter)
            throws IOException {
        int sum = 0;
        while (values.hasNext()) {
            sum += values.next().get();
        }
        reporter.getCounter(statistics.UNIQUE_TERMS).increment(1);
        if (sum < 5) {
            reporter.getCounter(statistics.LT5_TERM).increment(1);
        }

        if (this.top5.size() < 5) {
            top5.put(key.toString(), sum);
        } else {
            for (Entry<String, Integer> e : this.top5.entrySet()) {
                if (sum > e.getValue()) {
                    this.top5.remove(e.getKey());
                    this.top5.put(key.toString(), sum);
                    break;
                }
            }
        }

        output.collect(key, new IntWritable(sum));
    }

    protected void cleanup(org.apache.hadoop.mapreduce.Reducer.Context context) throws IOException, InterruptedException {
        System.out.println(this.top5);
    }
}

如何使方法按预期方式运行？
编辑：此问题也适用于 setup 方法和Map器中的。