spark--actions算子--collect

import org.apache.spark.{SparkConf, SparkContext}/**  * Created by liupeng on 2017/6/16.  */object A_collect {  System.setProperty("hadoop.home.dir","F:\\hadoop-2.6.5")  def main(args: Array[String]): Unit = {    val conf = new SparkConf().setAppName("collect_test").setMaster("local")    val sc = new SparkContext(conf)    //准备一下数据    val nameList : List[Int] = List(1,2,3,4,5)    val numbers = sc.parallelize(nameList)      .map(_ * 2)    //将RDD序列化到driver端    //建议用foreach action操作；collect在远程集群上遍历RDD的元素，将分布式的在远程集群里面的数据拉取到本地，如果数据量大，会走大量的网络传输，甚至有可能OOM内存溢出    val doubleNumbers : Array[Int] = numbers.collect()    for (num <- doubleNumbers)      {        println(num)      }  }}

运行结果：

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