一、BroadcastState 的介紹
廣播狀態(Broadcast State)是 Operator State 的一種特殊類型。如果我們需要將配置 、規則等低吞吐事件流廣播到下游所有 Task 時,就可以使用 BroadcastState。下游的 Task 接收這些配置、規則并保存為 BroadcastState,所有Task 中的狀態保持一致,作用于另一個數據流的計算中。
簡單理解:一個低吞吐量流包含一組規則,我們想對來自另一個流的所有元素基于此規則進行評估。
場景:動態更新計算規則。
廣播狀態與其他操作符狀態的區別在于:
- 它有一個 map 格式,用于定義存儲結構
- 它僅對具有廣播流和非廣播流輸入的特定操作符可用
- 這樣的操作符可以具有不同名稱的多個廣播狀態
二、BroadcastState 操作流程
三、案例實現
- 從端口讀取Json數據作為事件流
- 從Mysql讀取數據作為廣播流
- 關聯廣播流和事件流
- 匹配對應的用戶信息
package cn.kgc.broadcast import java.sql.{Connection, DriverManager, PreparedStatement} import com.alibaba.fastjson.JSON import org.apache.flink.api.common.state.{BroadcastState, MapStateDescriptor} import org.apache.flink.configuration.Configuration import org.apache.flink.streaming.api.datastream.BroadcastStream import org.apache.flink.streaming.api.functions.co.BroadcastProcessFunction import org.apache.flink.streaming.api.functions.source.{RichParallelSourceFunction, SourceFunction} import org.apache.flink.streaming.api.scala._ import org.apache.flink.util.Collector // (001,"tom",18,"北京",15830010002) // 定義樣例類 接受 MySQL的用戶數據 case class BaseUserInfo(id:Long,name:String,age:Int,city:String,phone:Long) // user_id、user_name、user_addrss、behaviour、url // 輸出數據類型 case class UserVisitInfo(id:Long,name:String,city:String,behaviour:String,url:String) // 實現廣播ProcessFunction class MyBroadcastFunc extends BroadcastProcessFunction[String,(Long, BaseUserInfo),UserVisitInfo]{ lazy val mapStateDes = new MapStateDescriptor[Long, BaseUserInfo]("mapState",classOf[Long],classOf[BaseUserInfo]) // 處理的是日志流中的每條數據 override def processElement(value: String, ctx: BroadcastProcessFunction[String, (Long, BaseUserInfo), UserVisitInfo]#ReadOnlyContext, out: Collector[UserVisitInfo]): Unit = { // {"user_id":"001","ts":"2021-07-10 11:10:05","behaviour":"browse","url":"https://www.tb1.com/1.html"} val user_id = JSON.parseObject(value).getLong("user_id") val behaviour = JSON.parseObject(value).getString("behaviour") val url = JSON.parseObject(value).getString("url") val mapState = ctx.getBroadcastState(mapStateDes) val userInfo = mapState.get(user_id) out.collect(UserVisitInfo(user_id,userInfo.name,userInfo.city,behaviour,url)) } // 處理的是廣播流的每個值 override def processBroadcastElement(value: (Long, BaseUserInfo), ctx: BroadcastProcessFunction[String, (Long, BaseUserInfo), UserVisitInfo]#Context, out: Collector[UserVisitInfo]): Unit = { val mapState: BroadcastState[Long, BaseUserInfo] = ctx.getBroadcastState(mapStateDes) mapState.put(value._1,value._2) } } class UserSourceFunc extends RichParallelSourceFunction[BaseUserInfo]{ var conn:Connection = _ var statement: PreparedStatement = _ var flag:Boolean = true override def open(parameters: Configuration): Unit = { conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/test?characterEncoding=utf-8&serverTimezone=UTC","root","liu911223") statement = conn.prepareStatement("select * from base_user") } override def run(ctx: SourceFunction.SourceContext[BaseUserInfo]): Unit = { while (flag){ Thread.sleep(5000) val resultSet = statement.executeQuery() while (resultSet.next()){ val id = resultSet.getLong(1) val name = resultSet.getString(2) val age = resultSet.getInt(3) val city = resultSet.getString(4) val phone = resultSet.getLong(5) ctx.collect(BaseUserInfo(id,name,age,city,phone)) } } } override def cancel(): Unit = { flag = false } override def close(): Unit = { if (statement != null) statement.close() if (conn != null) conn.close() } } object BroadcastDemo01 { def main(args: Array[String]): Unit = { val env = StreamExecutionEnvironment.getExecutionEnvironment env.setParallelism(1) // 定義為KV,一方面是為了廣播的時候定義為map,另一方面是為了做關聯操作 val userBaseDS: DataStream[(Long, BaseUserInfo)] = env.addSource(new UserSourceFunc) .map(user => (user.id, user)) val mapStateDes = new MapStateDescriptor[Long, BaseUserInfo]("mapState",classOf[Long],classOf[BaseUserInfo]) val broadCastStream: BroadcastStream[(Long, BaseUserInfo)] = userBaseDS.broadcast(mapStateDes) // 日志JSON數據 val dataInfoDS: DataStream[String] = env.socketTextStream("master",1314) dataInfoDS.connect(broadCastStream) .process(new MyBroadcastFunc) .print() env.execute() } }
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原文鏈接:https://blog.csdn.net/sweet19920711/article/details/120027690