怎么联合使用Spark Streaming、Broadcast、Accumulaor

蜗牛互联网技术资讯2021-12-162540

本篇内容介绍了“怎么联合使用Spark Streaming、Broadcast、Accumulaor”的有关知识，在实际案例的操作过程中，不少人都会遇到这样的困境，接下来就让小编带领大家学习一下如何处理这些情况吧！希望大家仔细阅读，能够学有所成！

广播可以自定义，通过Broadcast、Accumulator联合可以完成复杂的业务逻辑。

以下代码实现在本机9999端口监听，并向连接上的客户端发送单词，其中包含黑名单的单词Hadoop，Mahout和Hive。

package org.scala.opt

import java.io.{PrintWriter, IOException}
import java.net.{Socket, SocketException, ServerSocket}

case class ServerThread(socket : Socket) extends Thread("ServerThread") {
  override def run(): Unit = {
    val ptWriter = new PrintWriter(socket.getOutputStream)
    try {
      var count = 0
      var totalCount = 0
      var isThreadRunning : Boolean = true
      val batchCount = 1
      val words = List("Java Scala C C++ C# Python JavaScript",
      "Hadoop Spark Ngix MFC Net Mahout Hive")
      while (isThreadRunning) {
        words.foreach(ptWriter.println)
        count += 1
        if (count >= batchCount) {
          totalCount += count
          count = 0
          println("batch " + batchCount + " totalCount => " + totalCount)
          Thread.sleep(1000)
        }
        //out.println此类中的方法不会抛出 I/O 异常，尽管其某些构造方法可能抛出异常。客户端可能会查询调用 checkError() 是否出现错误。
        if(ptWriter.checkError()) {
          isThreadRunning = false
          println("ptWriter error then close socket")
        }
      }
    }
    catch {
      case e : SocketException =>
        println("SocketException : ", e)
      case e : IOException =>
        e.printStackTrace();
    } finally {
      if (ptWriter != null) ptWriter.close()
      println("Client " + socket.getInetAddress + " disconnected")
      if (socket != null) socket.close()
    }
    println(Thread.currentThread().getName + " Exit")
  }
}
object SocketServer {
  def main(args : Array[String]) : Unit = {
    try {
      val listener = new ServerSocket(9999)
      println("Server is started, waiting for client connect...")
      while (true) {
        val socket = listener.accept()
        println("Client : " + socket.getLocalAddress + " connected")
        new ServerThread(socket).start()
      }
      listener.close()
    }
    catch {
      case e: IOException =>
        System.err.println("Could not listen on port: 9999.")
        System.exit(-1)
    }
  }
}

以下代码实现接收本机9999端口发送的单词，统计黑名单出现的次数的功能。

package com.dt.spark.streaming_scala

import org.apache.spark.streaming.{Seconds, StreamingContext}
import org.apache.spark.{SparkConf, Accumulator}
import org.apache.spark.broadcast.Broadcast

/**
* 第103课：动手实战联合使用Spark Streaming、Broadcast、Accumulator实现在线黑名单过滤和计数
* 本期内容：
1，Spark Streaming与Broadcast、Accumulator联合
2，在线黑名单过滤和计算实战
*/
object _103SparkStreamingBroadcastAccumulator {

  @volatile private var broadcastList : Broadcast[List[String]] = null
  @volatile private var accumulator : Accumulator[Int] = null

  def main(args : Array[String]) : Unit = {
    val conf = new SparkConf().setMaster("local[5]").setAppName("_103SparkStreamingBroadcastAccumulator")
    val ssc = new StreamingContext(conf, Seconds(5))
    ssc.sparkContext.setLogLevel("WARN")

    /**
     * 使用Broadcast广播黑名单到每个Executor中
     */
    broadcastList = ssc.sparkContext.broadcast(Array("Hadoop", "Mahout", "Hive").toList)

    /**
     * 全局计数器，用于通知在线过滤了多少各黑名单
     */
    accumulator = ssc.sparkContext.accumulator(0, "OnlineBlackListCounter")

    ssc.socketTextStream("localhost", 9999).flatMap(_.split(" ")).map((_, 1)).reduceByKey(_+_).foreachRDD {rdd =>{
      if (!rdd.isEmpty()) {
        rdd.filter(wordPair => {
          if (broadcastList.value.contains(wordPair._1)) {

            println("BlackList word %s appeared".formatted(wordPair._1))
            accumulator.add(wordPair._2)
            false
          } else {
            true
          }
        }).collect()
        println("BlackList appeared : %d times".format(accumulator.value))
      }
    }}
    ssc.start()
    ssc.awaitTermination()
    ssc.stop()
  }
}