本期内容：
1、在线动态计算分类最热门商品案例回顾与演示
2、基于案例贯通Spark Streaming的运行源码
第一部分案例：
OnlineTheTop3ItemForEachCategory2DB.scala
package com.dt.spark.sparkstreaming
import com.robinspark.utils.ConnectionPool
import org.apache.spark.SparkConf
import org.apache.spark.sql.Row
import org.apache.spark.sql.hive.HiveContext
import org.apache.spark.sql.types.{IntegerType, StringType, StructField, StructType}
import org.apache.spark.streaming.{Seconds, StreamingContext}
/**
* 使用Spark Streaming+Spark SQL来在线动态计算电商中不同类别中最热门的商品排名，例如手机这个类别下面最热门的三种手机、电视这个类别
* 下最热门的三种电视，该实例在实际生产环境下具有非常重大的意义；
*
* @author DT大数据梦工厂
* 新浪微博：http://weibo.com/ilovepains/
*
*
* 实现技术：Spark Streaming+Spark SQL，之所以Spark Streaming能够使用ML、sql、graphx等功能是因为有foreachRDD和Transform
* 等接口，这些接口中其实是基于RDD进行操作，所以以RDD为基石，就可以直接使用Spark其它所有的功能，就像直接调用API一样简单。
* 假设说这里的数据的格式：user item category，例如Rocky Samsung Android
*/
object OnlineTheTop3ItemForEachCategory2DB {
def main(args: Array[String]){
/**
* 第1步：创建Spark的配置对象SparkConf，设置Spark程序的运行时的配置信息，
* 例如说通过setMaster来设置程序要链接的Spark集群的Master的URL,如果设置
* 为local，则代表Spark程序在本地运行，特别适合于机器配置条件非常差（例如
* 只有1G的内存）的初学者 *
*/
val conf = new SparkConf() //创建SparkConf对象
conf.setAppName("OnlineTheTop3ItemForEachCategory2DB") //设置应用程序的名称，在程序运行的监控界面可以看到名称
conf.setMaster("spark://Master:7077") //此时，程序在Spark集群
//conf.setMaster("local[2]")
//设置batchDuration时间间隔来控制Job生成的频率并且创建Spark Streaming执行的入口
val ssc = new StreamingContext(conf, Seconds(5))
ssc.checkpoint("/root/Documents/SparkApps/checkpoint")
val userClickLogsDStream = ssc.socketTextStream("Master", 9999)
val formattedUserClickLogsDStream = userClickLogsDStream.map(clickLog =>
(clickLog.split(" ")(2) + "_" + clickLog.split(" ")(1), 1))
// val categoryUserClickLogsDStream = formattedUserClickLogsDStream.reduceByKeyAndWindow((v1:Int, v2: Int) => v1 + v2,
// (v1:Int, v2: Int) => v1 - v2, Seconds(60), Seconds(20))
val categoryUserClickLogsDStream = formattedUserClickLogsDStream.reduceByKeyAndWindow(_+_,
_-_, Seconds(60), Seconds(20))
categoryUserClickLogsDStream.foreachRDD { rdd => {
if (rdd.isEmpty()) {
println("No data inputted!!!")
} else {
val categoryItemRow = rdd.map(reducedItem => {
val category = reducedItem._1.split("_")(0)
val item = reducedItem._1.split("_")(1)
val click_count = reducedItem._2
Row(category, item, click_count)
})
val structType = StructType(Array(
StructField("category", StringType, true),
StructField("item", StringType, true),
StructField("click_count", IntegerType, true)
))
val hiveContext = new HiveContext(rdd.context)
val categoryItemDF = hiveContext.createDataFrame(categoryItemRow, structType)
categoryItemDF.registerTempTable("categoryItemTable")
val reseltDataFram = hiveContext.sql("SELECT category,item,click_count FROM (SELECT category,item,click_count,row_number()" +
" OVER (PARTITION BY category ORDER BY click_count DESC) rank FROM categoryItemTable) subquery " +
" WHERE rank <= 3")
reseltDataFram.show()
val resultRowRDD = reseltDataFram.rdd
resultRowRDD.foreachPartition { partitionOfRecords => {
if (partitionOfRecords.isEmpty){
println("This RDD is not null but partition is null")
} else {
// ConnectionPool is a static, lazily initialized pool of connections
val connection = ConnectionPool.getConnection()
partitionOfRecords.foreach(record => {
val sql = "insert into categorytop3(category,item,client_count) values('" + record.getAs("category") + "','" +
record.getAs("item") + "'," + record.getAs("click_count") + ")"
val stmt = connection.createStatement();
stmt.executeUpdate(sql);
})
ConnectionPool.returnConnection(connection) // return to the pool for future reuse
}
}
}
}
}
}
/**
* 在StreamingContext调用start方法的内部其实是会启动JobScheduler的Start方法，进行消息循环，在JobScheduler
* 的start内部会构造JobGenerator和ReceiverTacker，并且调用JobGenerator和ReceiverTacker的start方法：
* 1，JobGenerator启动后会不断的根据batchDuration生成一个个的Job
* 2，ReceiverTracker启动后首先在Spark Cluster中启动Receiver（其实是在Executor中先启动ReceiverSupervisor），在Receiver收到
* 数据后会通过ReceiverSupervisor存储到Executor并且把数据的Metadata信息发送给Driver中的ReceiverTracker，在ReceiverTracker
* 内部会通过ReceivedBlockTracker来管理接受到的元数据信息
* 每个BatchInterval会产生一个具体的Job，其实这里的Job不是Spark Core中所指的Job，它只是基于DStreamGraph而生成的RDD
* 的DAG而已，从Java角度讲，相当于Runnable接口实例，此时要想运行Job需要提交给JobScheduler，在JobScheduler中通过线程池的方式找到一个
* 单独的线程来提交Job到集群运行（其实是在线程中基于RDD的Action触发真正的作业的运行），为什么使用线程池呢？
* 1，作业不断生成，所以为了提升效率，我们需要线程池；这和在Executor中通过线程池执行Task有异曲同工之妙；
* 2，有可能设置了Job的FAIR公平调度的方式，这个时候也需要多线程的支持；
*
*/
ssc.start()
ssc.awaitTermination()
}
}
第二部分源码解析：
1、构建StreamingContext时传递SparkConf参数（或者自己Configuration）在内部创建SparkContext
def this(conf: SparkConf, batchDuration: Duration) = {
this(StreamingContext.createNewSparkContext(conf), null, batchDuration)
}
2、事实说明SparkStreaming就是SparkCore上的一个应用程序
private[streaming] def createNewSparkContext(conf: SparkConf): SparkContext = {
new SparkContext(conf)
}
3、创建Socket输入流
def socketTextStream(
hostname: String,
port: Int,
storageLevel: StorageLevel = StorageLevel.MEMORY_AND_DISK_SER_2
): ReceiverInputDStream[String] = withNamedScope("socket text stream") {
socketStream[String](hostname, port, SocketReceiver.bytesToLines, storageLevel)
}
4、创建SocketInputDStream
def socketStream[T: ClassTag](
hostname: String,
port: Int,
converter: (InputStream) => Iterator[T],
storageLevel: StorageLevel
): ReceiverInputDStream[T] = {
new SocketInputDStream[T](this, hostname, port, converter, storageLevel)
}
5、SocketInputDstream继承ReceiverInputDStream，通过构建Receiver来接收数据
private[streaming]
class SocketInputDStream[T: ClassTag](
ssc_ : StreamingContext,
host: String,
port: Int,
bytesToObjects: InputStream => Iterator[T],
storageLevel: StorageLevel
) extends ReceiverInputDStream[T](ssc_) {
def getReceiver(): Receiver[T] = {
new SocketReceiver(host, port, bytesToObjects, storageLevel)
}
}
5.1、ReceiverInputDStream
abstract class ReceiverInputDStream[T: ClassTag](ssc_ : StreamingContext)
extends InputDStream[T](ssc_) {
abstract class InputDStream[T: ClassTag] (ssc_ : StreamingContext)
extends DStream[T](ssc_) {
5.2、DStream
/*
* DStreams internally is characterized by a few basic properties:
* - A list of other DStreams that the DStream depends on
* - A time interval at which the DStream generates an RDD
* - A function that is used to generate an RDD after each time interval
*/
1）、依赖于其他DStream
2）、什么时候依据DStream，依赖关系的模板，构成RDD之间的依赖
3）、基于DStream它有一个Function，Function 基于Batch Interval（time Interval）生成RDD，这个和定时器有关系
abstract class DStream[T: ClassTag] (
@transient private[streaming] var ssc: StreamingContext
) extends Serializable with Logging {
6、SocketReceiver对象在onStart中创建Thread启动run方法调用执行receive接收数据。
def onStart() {
// Start the thread that receives data over a connection
new Thread("Socket Receiver") {
setDaemon(true)
override def run() { receive() }
}.start()
}
7、创建一个Socket connection连接接收数据
/** Create a socket connection and receive data until receiver is stopped */ defreceive() { var socket: Socket = null try { logInfo("Connecting to " + host + ":" + port) socket = new Socket(host, port) logInfo("Connected to " + host + ":" + port) val iterator = bytesToObjects(socket.getInputStream()) while(!isStopped && iterator.hasNext) { store(iterator.next) } if (!isStopped()) { restart("Socket data stream had no more data") } else { logInfo("Stopped receiving") } } catch { case e: java.net.ConnectException => restart("Error connecting to " + host + ":" + port, e) case NonFatal(e) => logWarning("Error receiving data", e) restart("Error receiving data", e) } finally { if (socket != null) { socket.close() logInfo("Closed socket to " + host + ":" + port) } } }
8、总体流程：在StreamingContext调用start方法的内部其实是会启动JobScheduler的Start方法，进行消息循环，在JobScheduler的start内部会构造JobGenerator和ReceiverTacker，并且调用JobGenerator和ReceiverTacker的start方法：
1）、JobGenerator启动后会不断的根据batchDuration生成一个个的Job
2）、ReceiverTracker启动后首先在Spark Cluster中启动Receiver（其实是在Executor中先启动ReceiverSupervisor），
在Receiver收到数据后会通过ReceiverSupervisor存储到Executor并且把数据的Metadata信息发送给Driver中的ReceiverTracker，
在ReceiverTracker 内部会通过ReceivedBlockTracker来管理接受到的元数据信息每个BatchInterval会产生一个具体的Job（这里的Job主要是封装了业务逻辑例如上面实例中的代码），其实这里的Job不是Spark Core中所指的Job，它只是基于DStreamGraph而生成的RDD 的DAG而已，
从Java角度讲，相当于Runnable接口实例，此时要想运行Job需要提交给JobScheduler，在JobScheduler中通过线程池的方式找到一个单独的线程来提交Job到集群运行（其实是在线程中基于RDD的Action触发真正的作业的运行）,
为什么使用线程池呢？
a）、作业不断生成，所以为了提升效率，我们需要线程池；这和在Executor中通过线程池执行Task有异曲同工之妙；
b）、有可能设置了Job的FAIR公平调度的方式，这个时候也需要多线程的支持；
8.1、StreamingContext.start
// Start the streaming scheduler in a new thread, so that thread local properties
// like call sites and job groups can be reset without affecting those of the
// current thread.
ThreadUtils.runInNewThread("streaming-start") {
sparkContext.setCallSite(startSite.get)
sparkContext.clearJobGroup()
sparkContext.setLocalProperty(SparkContext.SPARK_JOB_INTERRUPT_ON_CANCEL, "false")
scheduler.start()
}
补充：线程本地存储，线程ThreadLocal每个线程有自己的私有属性，设置线程的私有属性不会影响当前线程或其他线程
9、JobScheduler.start 创建EventLoop消息线程并启动
def start(): Unit = synchronized {
if (eventLoop != null) return // scheduler has already been started
logDebug("Starting JobScheduler")
eventLoop = new EventLoop[JobSchedulerEvent]("JobScheduler") {
override protected def onReceive(event: JobSchedulerEvent): Unit = processEvent(event)
override protected def onError(e: Throwable): Unit = reportError("Error in job scheduler", e)
}
eventLoop.start()
9.1、EventLoop中创建Thread线程接收和发送消息，调用JobScheduler中的processEvent方法
private[spark] abstract class EventLoop[E](name: String) extends Logging {
private val eventQueue: BlockingQueue[E] = new LinkedBlockingDeque[E]()
private val stopped = new AtomicBoolean(false)
private val eventThread = new Thread(name) {
setDaemon(true)
override def run(): Unit = {
try {
while (!stopped.get) {
val event = eventQueue.take()
try {
onReceive(event)
} catch {
case NonFatal(e) => {
try {
onError(e)
} catch {
case NonFatal(e) => logError("Unexpected error in " + name, e)
}
}
}
}
} catch {
case ie: InterruptedException => // exit even if eventQueue is not empty
case NonFatal(e) => logError("Unexpected error in " + name, e)
}
}
}
9.2、会接受不同的任务，JobScheduler是整个Job的调度器，它本身用了一个线程循环，去监听不同的Job启动、Job完成、Job失败等任务（消息驱动系统）
private def processEvent(event: JobSchedulerEvent) {
try {
event match {
case JobStarted(job, startTime) => handleJobStart(job, startTime)
case JobCompleted(job, completedTime) => handleJobCompletion(job, completedTime)
case ErrorReported(m, e) => handleError(m, e)
}
} catch {
case e: Throwable =>
reportError("Error in job scheduler", e)
}
}
private def handleJobStart(job: Job, startTime: Long) {
val jobSet = jobSets.get(job.time)
val isFirstJobOfJobSet = !jobSet.hasStarted
jobSet.handleJobStart(job)
if (isFirstJobOfJobSet) {
// "StreamingListenerBatchStarted" should be posted after calling "handleJobStart" to get the
// correct "jobSet.processingStartTime".
listenerBus.post(StreamingListenerBatchStarted(jobSet.toBatchInfo))
}
job.setStartTime(startTime)
listenerBus.post(StreamingListenerOutputOperationStarted(job.toOutputOperationInfo))
logInfo("Starting job " + job.id + " from job set of time " + jobSet.time)
}
10、JobScheduler.start方法下
// attach rate controllers of input streams to receive batch completion updates
for {
inputDStream <- ssc.graph.getInputStreams
rateController <- inputDStream.rateController //可以控制输入
} ssc.addStreamingListener(rateController)
10.1、多个InputStream
inputDStream <- ssc.graph.getInputStreams
10.2、RateController控制输入的速度
// Keep track of the freshest rate for this stream using the rateEstimator
protected[streaming] val rateController: Option[RateController] = None
11、JobScheduler.start方法下
listenerBus.start(ssc.sparkContext) // listenerBus监听系统
receiverTracker = new ReceiverTracker(ssc)
inputInfoTracker = new InputInfoTracker(ssc)
receiverTracker.start()
jobGenerator.start()
logInfo("Started JobScheduler")
val listenerBus = new StreamingListenerBus()
11.1、StreamingListenerBus
override def onPostEvent(listener: StreamingListener, event: StreamingListenerEvent): Unit = {
event match {
case receiverStarted: StreamingListenerReceiverStarted =>
listener.onReceiverStarted(receiverStarted)
case receiverError: StreamingListenerReceiverError =>
listener.onReceiverError(receiverError)
case receiverStopped: StreamingListenerReceiverStopped =>
listener.onReceiverStopped(receiverStopped)
case batchSubmitted: StreamingListenerBatchSubmitted =>
listener.onBatchSubmitted(batchSubmitted)
case batchStarted: StreamingListenerBatchStarted =>
listener.onBatchStarted(batchStarted)
case batchCompleted: StreamingListenerBatchCompleted =>
listener.onBatchCompleted(batchCompleted)
case outputOperationStarted: StreamingListenerOutputOperationStarted =>
listener.onOutputOperationStarted(outputOperationStarted)
case outputOperationCompleted: StreamingListenerOutputOperationCompleted =>
listener.onOutputOperationCompleted(outputOperationCompleted)
case _ =>
}
11.2、receiverTracker.start()，ReceiveTracker是通过发Job的方式到集群的Executor上启动Receiver
/**
* Track all receivers' information. The key is the receiver id, the value is the receiver info.
* It's only accessed in ReceiverTrackerEndpoint.
*/
private val receiverTrackingInfos = new HashMap[Int, ReceiverTrackingInfo]
/**
* Store all preferred locations for all receivers. We need this information to schedule
* receivers. It's only accessed in ReceiverTrackerEndpoint.
*/
private val receiverPreferredLocations = new HashMap[Int, Option[String]]
/** Start the endpoint and receiver execution thread. */
def start(): Unit = synchronized {
if (isTrackerStarted) {
throw new SparkException("ReceiverTracker already started")
}
if (!receiverInputStreams.isEmpty) {
endpoint = ssc.env.rpcEnv.setupEndpoint(
"ReceiverTracker", new ReceiverTrackerEndpoint(ssc.env.rpcEnv))
if (!skipReceiverLaunch) launchReceivers()
logInfo("ReceiverTracker started")
trackerState = Started
}
}
11.2.1、创建一个ReceiverTrackerEndpoint消息通信体
/** RpcEndpoint to receive messages from the receivers. */
private class ReceiverTrackerEndpoint(override val rpcEnv: RpcEnv) extends ThreadSafeRpcEndpoint {
// TODO Remove this thread pool after https://github.com/apache/spark/issues/7385 is merged
private val submitJobThreadPool = ExecutionContext.fromExecutorService(
ThreadUtils.newDaemonCachedThreadPool("submit-job-thread-pool"))
private val walBatchingThreadPool = ExecutionContext.fromExecutorService(
ThreadUtils.newDaemonCachedThreadPool("wal-batching-thread-pool"))
@volatile private var active: Boolean = true
override def receive: PartialFunction[Any, Unit] = {
// Local messages
case StartAllReceivers(receivers) =>
val scheduledLocations = schedulingPolicy.scheduleReceivers(receivers, getExecutors)
for (receiver <- receivers) {
val executors = scheduledLocations(receiver.streamId)
updateReceiverScheduledExecutors(receiver.streamId, executors)
receiverPreferredLocations(receiver.streamId) = receiver.preferredLocation
startReceiver(receiver, executors)
}
case RestartReceiver(receiver) =>
// Old scheduled executors minus the ones that are not active any more
val oldScheduledExecutors = getStoredScheduledExecutors(receiver.streamId)
val scheduledLocations = if (oldScheduledExecutors.nonEmpty) {
// Try global scheduling again
oldScheduledExecutors
} else {
val oldReceiverInfo = receiverTrackingInfos(receiver.streamId)
// Clear "scheduledLocations" to indicate we are going to do local scheduling
val newReceiverInfo = oldReceiverInfo.copy(
state = ReceiverState.INACTIVE, scheduledLocations = None)
receiverTrackingInfos(receiver.streamId) = newReceiverInfo
schedulingPolicy.rescheduleReceiver(
receiver.streamId,
receiver.preferredLocation,
receiverTrackingInfos,
getExecutors)
}
// Assume there is one receiver restarting at one time, so we don't need to update
// receiverTrackingInfos
startReceiver(receiver, scheduledLocations)
case c: CleanupOldBlocks =>
receiverTrackingInfos.values.flatMap(_.endpoint).foreach(_.send(c))
case UpdateReceiverRateLimit(streamUID, newRate) =>
for (info <- receiverTrackingInfos.get(streamUID); eP <- info.endpoint) {
eP.send(UpdateRateLimit(newRate))
}
// Remote messages
case ReportError(streamId, message, error) =>
reportError(streamId, message, error)
}
11.2.1.1、ReceiverSchedulingPolicy.scheduleReceivers，从下面的代码中可以看出来在那些Executor上启动Receiver,以及怎么具体在Executor上启动Receiver
def scheduleReceivers(
receivers: Seq[Receiver[_]],
executors: Seq[ExecutorCacheTaskLocation]): Map[Int, Seq[TaskLocation]] = {
if (receivers.isEmpty) {
return Map.empty
}
if (executors.isEmpty) {
return receivers.map(_.streamId -> Seq.empty).toMap
}
val hostToExecutors = executors.groupBy(_.host)
val scheduledLocations = Array.fill(receivers.length)(new mutable.ArrayBuffer[TaskLocation])
val numReceiversOnExecutor = mutable.HashMap[ExecutorCacheTaskLocation, Int]()
// Set the initial value to 0
executors.foreach(e => numReceiversOnExecutor(e) = 0)
// Firstly, we need to respect "preferredLocation". So if a receiver has "preferredLocation",
// we need to make sure the "preferredLocation" is in the candidate scheduled executor list.
for (i <- 0 until receivers.length) {
// Note: preferredLocation is host but executors are host_executorId
receivers(i).preferredLocation.foreach { host =>
hostToExecutors.get(host) match {
case Some(executorsOnHost) =>
// preferredLocation is a known host. Select an executor that has the least receivers in
// this host
val leastScheduledExecutor =
executorsOnHost.minBy(executor => numReceiversOnExecutor(executor))
scheduledLocations(i) += leastScheduledExecutor
numReceiversOnExecutor(leastScheduledExecutor) =
numReceiversOnExecutor(leastScheduledExecutor) + 1
case None =>
// preferredLocation is an unknown host.
// Note: There are two cases:
// 1. This executor is not up. But it may be up later.
// 2. This executor is dead, or it's not a host in the cluster.
// Currently, simply add host to the scheduled executors.
// Note: host could be `HDFSCacheTaskLocation`, so use `TaskLocation.apply` to handle
// this case
scheduledLocations(i) += TaskLocation(host)
}
}
}
// For those receivers that don't have preferredLocation, make sure we assign at least one
// executor to them.
for (scheduledLocationsForOneReceiver <- scheduledLocations.filter(_.isEmpty)) {
// Select the executor that has the least receivers
val (leastScheduledExecutor, numReceivers) = numReceiversOnExecutor.minBy(_._2)
scheduledLocationsForOneReceiver += leastScheduledExecutor
numReceiversOnExecutor(leastScheduledExecutor) = numReceivers + 1
}
// Assign idle executors to receivers that have less executors
val idleExecutors = numReceiversOnExecutor.filter(_._2 == 0).map(_._1)
for (executor <- idleExecutors) {
// Assign an idle executor to the receiver that has least candidate executors.
val leastScheduledExecutors = scheduledLocations.minBy(_.size)
leastScheduledExecutors += executor
}
receivers.map(_.streamId).zip(scheduledLocations).toMap
}
补充：ReceiverTracker本身不直接监管Receiver，它是Driver级别的可间接地，用ReceiverSupervisor监控那台机器上Executor中的Receiver。
11.2.2、if (!skipReceiverLaunch) launchReceivers()
private def launchReceivers(): Unit = {
val receivers = receiverInputStreams.map(nis => {
val rcvr = nis.getReceiver()
rcvr.setReceiverId(nis.id)
rcvr
})
runDummySparkJob()
logInfo("Starting " + receivers.length + " receivers")
endpoint.send(StartAllReceivers(receivers))
}
11.2.2.1运行了一个Dummy的作业，确保所有的Slaves正常工作，保证所有的Receiver都在一台机器上
/**
* Run the dummy Spark job to ensure that all slaves have registered. This avoids all the
* receivers to be scheduled on the same node.
*
* TODO Should poll the executor number and wait for executors according to
* "spark.scheduler.minRegisteredResourcesRatio" and
* "spark.scheduler.maxRegisteredResourcesWaitingTime" rather than running a dummy job.
*/
private def runDummySparkJob(): Unit = {
if (!ssc.sparkContext.isLocal) {
ssc.sparkContext.makeRDD(1 to 50, 50).map(x => (x, 1)).reduceByKey(_ + _, 20).collect()
}
assert(getExecutors.nonEmpty)
}
11.2.2.2、endpoint.send(StartAllReceivers(receivers)
// endpoint is created when generator starts.
// This not being null means the tracker has been started and not stopped
private var endpoint: RpcEndpointRef = null
if (!receiverInputStreams.isEmpty) {
endpoint = ssc.env.rpcEnv.setupEndpoint(
"ReceiverTracker", new ReceiverTrackerEndpoint(ssc.env.rpcEnv))
if (!skipReceiverLaunch) launchReceivers()
logInfo("ReceiverTracker started")
trackerState = Started
}
ReceiverTrackerEndpoint
/** RpcEndpoint to receive messages from the receivers. */
private class ReceiverTrackerEndpoint(override val rpcEnv: RpcEnv) extends ThreadSafeRpcEndpoint {
// TODO Remove this thread pool after https://github.com/apache/spark/issues/7385 is merged
private val submitJobThreadPool = ExecutionContext.fromExecutorService(
ThreadUtils.newDaemonCachedThreadPool("submit-job-thread-pool"))
private val walBatchingThreadPool = ExecutionContext.fromExecutorService(
ThreadUtils.newDaemonCachedThreadPool("wal-batching-thread-pool"))
@volatile private var active: Boolean = true
override def receive: PartialFunction[Any, Unit] = {
// Local messages
case StartAllReceivers(receivers) =>
val scheduledLocations = schedulingPolicy.scheduleReceivers(receivers, getExecutors)
for (receiver <- receivers) {
val executors = scheduledLocations(receiver.streamId)
updateReceiverScheduledExecutors(receiver.streamId, executors)
receiverPreferredLocations(receiver.streamId) = receiver.preferredLocation
startReceiver(receiver, executors)
}
case RestartReceiver(receiver) =>
// Old scheduled executors minus the ones that are not active any more
val oldScheduledExecutors = getStoredScheduledExecutors(receiver.streamId)
val scheduledLocations = if (oldScheduledExecutors.nonEmpty) {
// Try global scheduling again
oldScheduledExecutors
} else {
val oldReceiverInfo = receiverTrackingInfos(receiver.streamId)
// Clear "scheduledLocations" to indicate we are going to do local scheduling
val newReceiverInfo = oldReceiverInfo.copy(
state = ReceiverState.INACTIVE, scheduledLocations = None)
receiverTrackingInfos(receiver.streamId) = newReceiverInfo
schedulingPolicy.rescheduleReceiver(
receiver.streamId,
receiver.preferredLocation,
receiverTrackingInfos,
getExecutors)
}
// Assume there is one receiver restarting at one time, so we don't need to update
// receiverTrackingInfos
startReceiver(receiver, scheduledLocations)
case c: CleanupOldBlocks =>
receiverTrackingInfos.values.flatMap(_.endpoint).foreach(_.send(c))
case UpdateReceiverRateLimit(streamUID, newRate) =>
for (info <- receiverTrackingInfos.get(streamUID); eP <- info.endpoint) {
eP.send(UpdateRateLimit(newRate))
}
// Remote messages
case ReportError(streamId, message, error) =>
reportError(streamId, message, error)
}
startReceiver
private def startReceiver(
receiver: Receiver[_],
scheduledLocations: Seq[TaskLocation]): Unit = {
def shouldStartReceiver: Boolean = {
// It's okay to start when trackerState is Initialized or Started
!(isTrackerStopping || isTrackerStopped)
}
val receiverId = receiver.streamId
if (!shouldStartReceiver) {
onReceiverJobFinish(receiverId)
return
}
val checkpointDirOption = Option(ssc.checkpointDir)
val serializableHadoopConf =
new SerializableConfiguration(ssc.sparkContext.hadoopConfiguration)
// Function to start the receiver on the worker node
val startReceiverFunc: Iterator[Receiver[_]] => Unit =
(iterator: Iterator[Receiver[_]]) => {
if (!iterator.hasNext) {
throw new SparkException(
"Could not start receiver as object not found.")
}
if (TaskContext.get().attemptNumber() == 0) {
val receiver = iterator.next()
assert(iterator.hasNext == false)
val supervisor = new ReceiverSupervisorImpl(
receiver, SparkEnv.get, serializableHadoopConf.value, checkpointDirOption)
supervisor.start()
supervisor.awaitTermination()
} else {
// It's restarted by TaskScheduler, but we want to reschedule it again. So exit it.
}
}
逆天的设计啊
// Create the RDD using the scheduledLocations to run the receiver in a Spark job val receiverRDD: RDD[Receiver[_]] = if (scheduledLocations.isEmpty) { ssc.sc.makeRDD(Seq(receiver), 1) } else { val preferredLocations = scheduledLocations.map(_.toString).distinct ssc.sc.makeRDD(Seq(receiver -> preferredLocations)) } receiverRDD.setName(s"Receiver $receiverId") ssc.sparkContext.setJobDescription(s"Streaming job running receiver $receiverId") ssc.sparkContext.setCallSite(Option(ssc.getStartSite()).getOrElse(Utils.getCallSite())) val future = ssc.sparkContext.submitJob[Receiver[_], Unit, Unit]( receiverRDD, startReceiverFunc, Seq(0), (_, _) => Unit, ()) // We will keep restarting the receiver job until ReceiverTracker is stopped future.onComplete { case Success(_) => if (!shouldStartReceiver) { onReceiverJobFinish(receiverId) } else { logInfo(s"Restarting Receiver $receiverId") self.send(RestartReceiver(receiver)) } case Failure(e) => if (!shouldStartReceiver) { onReceiverJobFinish(receiverId) } else { logError("Receiver has been stopped. Try to restart it.", e) logInfo(s"Restarting Receiver $receiverId") self.send(RestartReceiver(receiver)) } }(submitJobThreadPool) logInfo(s"Receiver ${receiver.streamId} started") }
ReceiverSupervisor.startReceiver
/** Start the supervisor */
def start() {
onStart()
startReceiver()
}
/** Start receiver */
def startReceiver(): Unit = synchronized {
try {
if (onReceiverStart()) {
logInfo("Starting receiver")
receiverState = Started
receiver.onStart()
logInfo("Called receiver onStart")
} else {
// The driver refused us
stop("Registered unsuccessfully because Driver refused to start receiver " + streamId, None)
}
} catch {
case NonFatal(t) =>
stop("Error starting receiver " + streamId, Some(t))
}
}
ReceiverSupervisorImpl类
override protected def onReceiverStart(): Boolean = {
val msg = RegisterReceiver(
streamId, receiver.getClass.getSimpleName, host, executorId, endpoint)
trackerEndpoint.askWithRetry[Boolean](msg)
}
/** Remote RpcEndpointRef for the ReceiverTracker */
private val trackerEndpoint = RpcUtils.makeDriverRef("ReceiverTracker", env.conf, env.rpcEnv)
11.3、JobScheduler.start jobGenerator.start()
/** Start generation of jobs */
def start(): Unit = synchronized {
if (eventLoop != null) return // generator has already been started
// Call checkpointWriter here to initialize it before eventLoop uses it to avoid a deadlock.
// See SPARK-10125
checkpointWriter
eventLoop = new EventLoop[JobGeneratorEvent]("JobGenerator") {
override protected def onReceive(event: JobGeneratorEvent): Unit = processEvent(event)
override protected def onError(e: Throwable): Unit = {
jobScheduler.reportError("Error in job generator", e)
}
}
eventLoop.start()
if (ssc.isCheckpointPresent) {
restart()
} else {
startFirstTime()
}
}
根据时间间隔不断发送消息
/** Processes all events */
private def processEvent(event: JobGeneratorEvent) {
logDebug("Got event " + event)
event match {
case GenerateJobs(time) => generateJobs(time)
case ClearMetadata(time) => clearMetadata(time)
case DoCheckpoint(time, clearCheckpointDataLater) =>
doCheckpoint(time, clearCheckpointDataLater)
case ClearCheckpointData(time) => clearCheckpointData(time)
}
}
/** Generate jobs and perform checkpoint for the given `time`. */
private def generateJobs(time: Time) {
// Set the SparkEnv in this thread, so that job generation code can access the environment
// Example: BlockRDDs are created in this thread, and it needs to access BlockManager
// Update: This is probably redundant after threadlocal stuff in SparkEnv has been removed.
SparkEnv.set(ssc.env)
Try {
jobScheduler.receiverTracker.allocateBlocksToBatch(time) // allocate received blocks to batch
graph.generateJobs(time) // generate jobs using allocated block
} match {
case Success(jobs) =>
val streamIdToInputInfos = jobScheduler.inputInfoTracker.getInfo(time)
jobScheduler.submitJobSet(JobSet(time, jobs, streamIdToInputInfos))
case Failure(e) =>
jobScheduler.reportError("Error generating jobs for time " + time, e)
}
eventLoop.post(DoCheckpoint(time, clearCheckpointDataLater = false))
}
def submitJobSet(jobSet: JobSet) {
if (jobSet.jobs.isEmpty) {
logInfo("No jobs added for time " + jobSet.time)
} else {
listenerBus.post(StreamingListenerBatchSubmitted(jobSet.toBatchInfo))
jobSets.put(jobSet.time, jobSet)
jobSet.jobs.foreach(job => jobExecutor.execute(new JobHandler(job)))
logInfo("Added jobs for time " + jobSet.time)
}
}
public void execute(Runnable command) {
if (command == null)
throw new NullPointerException();
/*
* Proceed in 3 steps:
*
* 1. If fewer than corePoolSize threads are running, try to
* start a new thread with the given command as its first
* task. The call to addWorker atomically checks runState and
* workerCount, and so prevents false alarms that would add
* threads when it shouldn't, by returning false.
*
* 2. If a task can be successfully queued, then we still need
* to double-check whether we should have added a thread
* (because existing ones died since last checking) or that
* the pool shut down since entry into this method. So we
* recheck state and if necessary roll back the enqueuing if
* stopped, or start a new thread if there are none.
*
* 3. If we cannot queue task, then we try to add a new
* thread. If it fails, we know we are shut down or saturated
* and so reject the task.
*/
int c = ctl.get();
if (workerCountOf(c) < corePoolSize) {
if (addWorker(command, true))
return;
c = ctl.get();
}
if (isRunning(c) && workQueue.offer(command)) {
int recheck = ctl.get();
if (! isRunning(recheck) && remove(command))
reject(command);
else if (workerCountOf(recheck) == 0)
addWorker(null, false);
}
else if (!addWorker(command, false))
reject(command);
}
private class JobHandler(job: Job) extends Runnable with Logging {
import JobScheduler._
def run() {
try {
val formattedTime = UIUtils.formatBatchTime(
job.time.milliseconds, ssc.graph.batchDuration.milliseconds, showYYYYMMSS = false)
val batchUrl = s"/streaming/batch/?id=${job.time.milliseconds}"
val batchLinkText = s"[output operation ${job.outputOpId}, batch time ${formattedTime}]"
ssc.sc.setJobDescription(
s"""Streaming job from <a href="$batchUrl">$batchLinkText</a>""")
ssc.sc.setLocalProperty(BATCH_TIME_PROPERTY_KEY, job.time.milliseconds.toString)
ssc.sc.setLocalProperty(OUTPUT_OP_ID_PROPERTY_KEY, job.outputOpId.toString)
// We need to assign `eventLoop` to a temp variable. Otherwise, because
// `JobScheduler.stop(false)` may set `eventLoop` to null when this method is running, then
// it's possible that when `post` is called, `eventLoop` happens to null.
var _eventLoop = eventLoop
if (_eventLoop != null) {
_eventLoop.post(JobStarted(job, clock.getTimeMillis()))
// Disable checks for existing output directories in jobs launched by the streaming
// scheduler, since we may need to write output to an existing directory during checkpoint
// recovery; see SPARK-4835 for more details.
PairRDDFunctions.disableOutputSpecValidation.withValue(true) {
job.run()
}
_eventLoop = eventLoop
if (_eventLoop != null) {
_eventLoop.post(JobCompleted(job, clock.getTimeMillis()))
}
} else {
// JobScheduler has been stopped.
}
} finally {
ssc.sc.setLocalProperty(JobScheduler.BATCH_TIME_PROPERTY_KEY, null)
ssc.sc.setLocalProperty(JobScheduler.OUTPUT_OP_ID_PROPERTY_KEY, null)
}
}
}
}
博主：罗白莲
资料来源于：王家林（Spark版本定制班课程）
新浪微博：http://www.weibo.com/ilovepains
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