1. 启动脚本
sbin/
1. # Launch the slaves
2. if [ "$SPARK_WORKER_INSTANCES" = "" ]; then
3. exec "$sbin/" cd "$SPARK_HOME" \; "$sbin/" 1 "spark://$SPARK_MASTER_IP:$SPARK_MASTER_PORT"
4. else
5. if [ "$SPARK_WORKER_WEBUI_PORT" = "" ]; then
6. SPARK_WORKER_WEBUI_PORT=8081
7. fi
8. for ((i=0; i<$SPARK_WORKER_INSTANCES; i++)); do
9. "$sbin/" cd "$SPARK_HOME" \; "$sbin/" $(( $i + 1 )) "spark://$SPARK_MASTER_IP:$SPARK_MASTER_PORT" --webui-port $(( $SPARK_WORKER_WEBUI_PORT + $i ))
10. done
11. fi
假设每个节点启动一个Worker。
具体执行:
1. exec "$sbin/" cd "$SPARK_HOME" \; "$sbin/" 1 "spark://$SPARK_MASTER_IP:$SPARK_MASTER_PORT"
该语句分为两部分:
(1)
1. exec "$sbin/" cd "$SPARK_HOME"
登录到worker服务器并cd到SPARK_HOME目录。
(2)
1. "$sbin/" 1 "spark://$SPARK_MASTER_IP:$SPARK_MASTER_PORT"
在worker服务器执行sbin/脚本。
参数“1”代码worker的编号,用来区分不同worker实例的日志文件。如:
1. spark-xxx-org.apache.spark.deploy.worker.Worker-1-CentOS-02.out
2. spark-xxx-org.apache.spark.deploy.worker.Worker-1.pid
其中“Worker-1”中的“1”就代表worker编号。
这个参数并不会传入Worker类。传入Worker类的参数为:
spark://$SPARK_MASTER_IP:$SPARK_MASTER_PORT。
2. Worker.main
1. def main(argStrings: Array[String]) {
2. SignalLogger.register(log)
3. val conf = new SparkConf
4. val args = new WorkerArguments(argStrings, conf)
5. val (actorSystem, _) = startSystemAndActor(args.host, args.port, args.webUiPort, args.cores,
6. args.memory, args.masters, args.workDir)
7. actorSystem.awaitTermination()
8. }
main函数的职责:
(1)创建WorkerArguments对象并初始化其成员;
(2)调用startSystemAndActor方法,创建ActorSystem对象并启动Worker actor;
2.1. WorkerArguments
1. var cores = inferDefaultCores()
2. var memory = inferDefaultMemory()
(1)计算默认核数
(2)计算默认内存大小
1. parse(args.toList)
2.
3. // This mutates the SparkConf, so all accesses to it must be made after this line
4. propertiesFile = Utils.loadDefaultSparkProperties(conf, propertiesFile)
(1)parse方法负责解析启动脚本所带的命令行参数;
(2)loadDefaultSparkProperties负责从配置文件中加载spark运行属性,默认而配置文件为spark-defaults.conf;
2.2. startSystemAndActor
1. val (actorSystem, boundPort) = AkkaUtils.createActorSystem(systemName, host, port,
2. conf = conf, securityManager = securityMgr)
3. val masterAkkaUrls = masterUrls.map(Master.toAkkaUrl(_, AkkaUtils.protocol(actorSystem)))
4. actorSystem.actorOf(Props(classOf[Worker], host, boundPort, webUiPort, cores, memory,
5. masterAkkaUrls, systemName, actorName, workDir, conf, securityMgr), name = actorName)
(1)通过AkkaUtils.createActorSystem创建ActorSystem对象
(2)创建Worker actor并启动
3. Worker Actor
3.1. 重要数据成员
1. val executors = new HashMap[String, ExecutorRunner]
2. val finishedExecutors = new HashMap[String, ExecutorRunner]
3. val drivers = new HashMap[String, DriverRunner]
4. val finishedDrivers = new HashMap[String, DriverRunner]
5. val appDirectories = new HashMap[String, Seq[String]]
6. val finishedApps = new HashSet[String]
3.2. Worker.preStart
1. createWorkDir()
2. context.system.eventStream.subscribe(self, classOf[RemotingLifecycleEvent])
3. shuffleService.startIfEnabled()
4. webUi = new WorkerWebUI(this, workDir, webUiPort)
5. webUi.bind()
6. registerWithMaster()
(1)创建Worker节点工作目录;
(2)监听RemotingLifecycleEvent事件,它一个trait:
1. sealed trait RemotingLifecycleEvent extends Serializable {
2. def logLevel: Logging.LogLevel
3. }
Worker只处理了DisassociatedEvent消息。
(3)创建并启动WorkerWebUI
(4)向Master进行注册,registerWithMaster将调用tryRegisterAllMasters方法向Master节点发送注册消息
3.3. Worker.registerWithMaster
1. registrationRetryTimer match {
2. case None =>
3. registered = false
4. tryRegisterAllMasters()
5. connectionAttemptCount = 0
6. registrationRetryTimer = Some {
7. context.system.scheduler.schedule(INITIAL_REGISTRATION_RETRY_INTERVAL,
8. INITIAL_REGISTRATION_RETRY_INTERVAL, self, ReregisterWithMaster)
9. }
10. case Some(_) =>
11. logInfo("Not spawning another attempt to register with the master, since there is an" +
12. " attempt scheduled already.")
13. }
(1)调用tryRegisterAllMasters方法向Master发起注册消息;
(2)创建注册重试定时器,通过向自己(Worker Actor)发送ReregisterWithMaster消息;
3.3.1. Worker.tryRegisterAllMasters
1. for (masterAkkaUrl <- masterAkkaUrls) {
2. logInfo("Connecting to master " + masterAkkaUrl + "...")
3. val actor = context.actorSelection(masterAkkaUrl)
4. actor ! RegisterWorker(workerId, host, port, cores, memory, webUi.boundPort, publicAddress)
5. }
(1)创建Master Actor远程引用;
(2)向Master发送RegisterWorker消息;如果注册成功,Master将向Worker发送RegisteredWorker消息。
workerId是一个字符串,定义:
1. val workerId = generateWorkerId()
2. ...
3. def generateWorkerId(): String = {
4. "worker-%s-%s-%d".format(createDateFormat.format(new Date), host, port)
5. }
格式:worker-时间-主机名-端口
3.4. Worker消息处理
3.4.1. RegisteredWorker消息
此消息表示Worker向Master注册成功消息;该消息处理的主要目的是启动心跳发送定时器。
1. case RegisteredWorker(masterUrl, masterWebUiUrl) =>
2. logInfo("Successfully registered with master " + masterUrl)
3. registered = true
4. changeMaster(masterUrl, masterWebUiUrl)
5. context.system.scheduler.schedule(0 millis, HEARTBEAT_MILLIS millis, self, SendHeartbeat)
6. if (CLEANUP_ENABLED) {
7. logInfo(s"Worker cleanup enabled; old application directories will be deleted in: $workDir")
8. context.system.scheduler.schedule(CLEANUP_INTERVAL_MILLIS millis,
9. CLEANUP_INTERVAL_MILLIS millis, self, WorkDirCleanup)
10. }
(1)设置注册状态;
(2)调用changeMaster方法
(3)创建心跳发送定时器,向自己(Worker Actor)发送SendHeartbeat消息;
3.4.1.1. Worker.changeMaster
1. // activeMasterUrl it's a valid Spark url since we receive it from master.
2. activeMasterUrl = url
3. activeMasterWebUiUrl = uiUrl
4. master = context.actorSelection(
5. Master.toAkkaUrl(activeMasterUrl, AkkaUtils.protocol(context.system)))
6. masterAddress = Master.toAkkaAddress(activeMasterUrl, AkkaUtils.protocol(context.system))
7. connected = true
8. // Cancel any outstanding re-registration attempts because we found a new master
9. registrationRetryTimer.foreach(_.cancel())
10. registrationRetryTimer = None
职责:
(1)创建Master远程引用并赋值给master;
(2)将连接状态设置为true;
(3)取消registrationRetryTimer定时器;
3.4.2. SendHeartbeat消息
1. case SendHeartbeat =>
2. if (connected) { master ! Heartbeat(workerId) }
向master发送Heartbeat消息。
3.4.3. ReregisterWithMaster消息
1. case ReregisterWithMaster =>
2. reregisterWithMaster()
reregisterWithMaster方法职责:
(1)如果已经注册成功,取消registrationRetryTimer定时器;
(2)如果注册失败,从新向master发送RegisterWorker消息;初始默认重连次数为6,最大重连次数为16。
1. // The first six attempts to reconnect are in shorter intervals (between 5 and 15 seconds)
2. // Afterwards, the next 10 attempts are between 30 and 90 seconds.
3. // A bit of randomness is introduced so that not all of the workers attempt to reconnect at
4. // the same time.
5. val INITIAL_REGISTRATION_RETRIES = 6
6. val TOTAL_REGISTRATION_RETRIES = INITIAL_REGISTRATION_RETRIES + 10
前6次和后10次采用不同的周期。
4. 启动结束
到此,Worker节点就启动完成,它定时向Master节点发送心跳。在SparkSubmit提交Application时,将接收Master发送的启动Executor消息,由Executor和Driver进行消息通信。