问map()函数的调用次数与MR作业中发出的map任务数之间的关系

EN

    public static class Map extends MapReduceBase implements Mapper<LongWritable, Text, Text, LongWritable> {

            private final static Text  INCIRCLE             = new Text("INCIRCLE");
            private final static LongWritable TimesInAMap   = new LongWritable(100000000);
            private static Random random = new Random();

            public  class MyPoint {
                    private double  x = 0.0;
                    private double  y = 0.0;

                    MyPoint(double _x,double _y) {
                            this.x = _x;
                            this.y = _y;
                    }

                    public boolean inCircle() {
                            if ( ((x-0.5)*(x-0.5) + (y-0.5)*(y-0.5)) <= 0.25 )
                                    return true;
                            else
                                    return false;
                    }

                    public void setPoint(double _x,double _y) {
                            this.x = _x;
                            this.y = _y;
                    }
            }
            public void map(LongWritable key, Text value, OutputCollector<Text, LongWritable> output, Reporter reporter) throws IOException {
                            long i = 0;
                            long N = TimesInAMap.get();
                            MyPoint myPoint = new MyPoint(random.nextDouble(),random.nextDouble());
                            long sum = 0;
                            while (i < N ) {
                            if (myPoint.inCircle()) {                                           
                                sum++;
                            }
                            myPoint.setPoint(random.nextDouble(),random.nextDouble());
                            i++;
                            }
                            output.collect(INCIRCLE, new LongWritable(sum));
                            }
            }


    public static class Reduce extends MapReduceBase implements Reducer<Text, LongWritable, Text, LongWritable> {
  public void reduce(Text key, Iterator<LongWritable> values, OutputCollector<Text, LongWritable> output, Reporter reporter) throws IOException {
      long sum = 0;
      while (values.hasNext()) {
        //sum += values.next().get();
        output.collect(key, values.next());
      }
      //output.collect(key, new LongWritable(sum));
  }
  }
    public static void main(String[] args) throws Exception {
  JobConf conf = new JobConf(PiEstimation.class);
  conf.setJobName("PiEstimation");

  conf.setOutputKeyClass(Text.class);
  conf.setOutputValueClass(LongWritable.class);

  conf.setMapperClass(Map.class);
  conf.setCombinerClass(Reduce.class);
  conf.setReducerClass(Reduce.class);

  conf.setInputFormat(TextInputFormat.class);
  conf.setOutputFormat(TextOutputFormat.class);
  conf.setNumMapTasks(10);
  conf.setNumReduceTasks(1);
  FileInputFormat.setInputPaths(conf, new Path(args[0]));
  FileOutputFormat.setOutputPath(conf, new Path(args[1]));

  JobClient.runJob(conf);
}