相关疑难解决方法(0)

在http://spark.apache.org/docs/0.8.0/cluster-overview.html上阅读了一些文档后,我得到了一些我想澄清的问题.

以Spark为例:

JavaSparkContext spark = new JavaSparkContext(
  new SparkConf().setJars("...").setSparkHome....);
JavaRDD<String> file = spark.textFile("hdfs://...");

// step1
JavaRDD<String> words =
  file.flatMap(new FlatMapFunction<String, String>() {
    public Iterable<String> call(String s) {
      return Arrays.asList(s.split(" "));
    }
  });

// step2
JavaPairRDD<String, Integer> pairs =
  words.map(new PairFunction<String, String, Integer>() {
    public Tuple2<String, Integer> call(String s) {
      return new Tuple2<String, Integer>(s, 1);
    }
  });

// step3
JavaPairRDD<String, Integer> counts =
  pairs.reduceByKey(new Function2<Integer, Integer>() {
    public Integer call(Integer a, Integer b) {
      return a + b;
    } …