第11课：Spark Streaming源码解读之Driver中的ReceiverTracker架构设计以及具体实现彻底研究

本期内容：

1.ReceiverTracker的架构设计

2．消息循环系统

3．ReceiverTracker具体实现

 

启动Receiver的方式：

1．把每个Receiver都封装成为task,这个task是这个job中唯一的task,实质上讲ReceiverTracker启动Receiver的方式就是封装成一个一个的job，有多少个job就会启动多少Receiver。每个task就一条数据，就是Receiver的数据。

2.ReceiverTracker在启动Receiver的时候有一个ReceiverSupervisor, ReceiverSupervisorImp做为ReceiverSupervisor的实现，ReceiverSupervisor在启动的时候会启动Receiver，然后Receiver不断的接收数据，会通过blockGenerate把自己接收的数据变成一个一个的block,背后自己有个定时器，这个定时器会不断的存储数据。一种是直接通过blockGenerate存储，一种是先写日志WAL。ReceiverSupervisorImpl会把存储的元数据汇报给ReceiverTracker（实际上是ReceiverTracker中的RPC通信消息实体）。后面进行下一步的数据管理工作。

 

数据的大小一般从多少记录考虑，例如10亿级别的

源码

ReceivedBlockHandler

//写数据的时候是通过ReceivedBlockHandler
private val receivedBlockHandler: ReceivedBlockHandler = {
  if (WriteAheadLogUtils.enableReceiverLog(env.conf)) {
    if (checkpointDirOption.isEmpty) {
      throw new SparkException(
        "Cannot enable receiver write-ahead log without checkpoint directory set. "+
          "Please use streamingContext.checkpoint() to set the checkpoint directory. "+
          "See documentation for more details.")
    }
    new WriteAheadLogBasedBlockHandler(env.blockManager, receiver.streamId,
      receiver.storageLevel, env.conf, hadoopConf, checkpointDirOption.get)
  } else {
    new BlockManagerBasedBlockHandler(env.blockManager, receiver.storageLevel)
  }
}

pushAndReportBlock

//存储数据且把数据汇报给Driver
def pushAndReportBlock(
    receivedBlock: ReceivedBlock,
    metadataOption: Option[Any],
    blockIdOption: Option[StreamBlockId]
  ) {
  val blockId = blockIdOption.getOrElse(nextBlockId)
  val time = System.currentTimeMillis
  val blockStoreResult =receivedBlockHandler.storeBlock(blockId, receivedBlock)
  logDebug(s"Pushed block $blockId in${(System.currentTimeMillis- time)} ms")
  val numRecords = blockStoreResult.numRecords
  val blockInfo =ReceivedBlockInfo(streamId, numRecords, metadataOption, blockStoreResult)
  trackerEndpoint.askWithRetry[Boolean](AddBlock(blockInfo))
  logDebug(s"Reported block $blockId")
}

private[streaming]case class ReceivedBlockInfo(
    streamId: Int,
    numRecords: Option[Long],
    metadataOption: Option[Any],
    blockStoreResult: ReceivedBlockStoreResult
  ) {

 

/** Remote RpcEndpointRef for the ReceiverTracker */
private val trackerEndpoint= RpcUtils.makeDriverRef("ReceiverTracker", env.conf, env.rpcEnv)

 

 

ReceiverTracker是整个block管理的中心

//RPC消息循环体接收来自receiver的消息
private class ReceiverTrackerEndpoint(override valrpcEnv: RpcEnv) extendsThreadSafeRpcEndpoint {

 

//sealed说明所有的消息都在这里
private[streaming]sealed trait ReceiverTrackerMessage
private[streaming]case class RegisterReceiver(
    streamId: Int,
    typ: String,
    host: String,
    executorId: String,
    receiverEndpoint: RpcEndpointRef
  ) extends ReceiverTrackerMessage
private[streaming]case class AddBlock(receivedBlockInfo: ReceivedBlockInfo)
  extends ReceiverTrackerMessage
private[streaming]case class ReportError(streamId: Int, message:String, error:String)
private[streaming]case class DeregisterReceiver(streamId: Int, msg:String, error:String)
  extends ReceiverTrackerMessage

receiveAndReply

override defreceiveAndReply(context: RpcCallContext): PartialFunction[Any, Unit] = {
  // Remote messages
  case RegisterReceiver(streamId, typ, host, executorId, receiverEndpoint) =>
    val successful =
      registerReceiver(streamId, typ, host, executorId, receiverEndpoint, context.senderAddress)
    context.reply(successful)
  case AddBlock(receivedBlockInfo) =>
    if (WriteAheadLogUtils.isBatchingEnabled(ssc.conf, isDriver =true)) {
      walBatchingThreadPool.execute(newRunnable {
        override def run(): Unit = Utils.tryLogNonFatalError{
          if (active) {
            context.reply(addBlock(receivedBlockInfo))
          } else {
            throw new IllegalStateException("ReceiverTracker RpcEndpoint shut down.")
          }
        }
      })
    } else {
      context.reply(addBlock(receivedBlockInfo))
    }
  case DeregisterReceiver(streamId, message, error) =>
    deregisterReceiver(streamId, message, error)
    context.reply(true)
  // Local messages
  case AllReceiverIds =>
    context.reply(receiverTrackingInfos.filter(_._2.state != ReceiverState.INACTIVE).keys.toSeq)
  case StopAllReceivers =>
    assert(isTrackerStopping || isTrackerStopped)
    stopReceivers()
    context.reply(true)
}

addBlock

/** Add new blocks for the given stream */
private def addBlock(receivedBlockInfo: ReceivedBlockInfo): Boolean = {
  receivedBlockTracker.addBlock(receivedBlockInfo)
}

 

/** Add received block. This event will get written to the write ahead log (if enabled). */
def addBlock(receivedBlockInfo: ReceivedBlockInfo): Boolean = {
  try {
    val writeResult =writeToLog(BlockAdditionEvent(receivedBlockInfo))
    if (writeResult) {
      synchronized {
        getReceivedBlockQueue(receivedBlockInfo.streamId) += receivedBlockInfo
      }
      logDebug(s"Stream ${receivedBlockInfo.streamId} received "+
        s"block ${receivedBlockInfo.blockStoreResult.blockId}")
    } else {
      logDebug(s"Failed to acknowledge stream${receivedBlockInfo.streamId} receiving "+
        s"block ${receivedBlockInfo.blockStoreResult.blockId} in the Write Ahead Log.")
    }
    writeResult
  } catch {
    case NonFatal(e) =>
      logError(s"Error adding block $receivedBlockInfo", e)
      false
  }
}

/** Write an update to the tracker to the write ahead log */
private def writeToLog(record: ReceivedBlockTrackerLogEvent): Boolean = {
  if (isWriteAheadLogEnabled) {
    logTrace(s"Writing record: $record")
    try {
      writeAheadLogOption.get.write(ByteBuffer.wrap(Utils.serialize(record)),
        clock.getTimeMillis())
      true
    } catch{
      case NonFatal(e) =>
        logWarning(s"Exception thrown while writing record:$record to the WriteAheadLog.", e)
        false
    }
  } else {
    true
  }
}

/** Get the queue of received blocks belonging to a particular stream */
private def getReceivedBlockQueue(streamId: Int):ReceivedBlockQueue = {
  streamIdToUnallocatedBlockQueues.getOrElseUpdate(streamId,new ReceivedBlockQueue)
}

//没有被分配,只是做记录
  private val streamIdToUnallocatedBlockQueues= newmutable.HashMap[Int, ReceivedBlockQueue]
 

/** Allocate all unallocated blocks to the given batch. */
def allocateBlocksToBatch(batchTime: Time): Unit = {
  if (receiverInputStreams.nonEmpty) {
    receivedBlockTracker.allocateBlocksToBatch(batchTime)
  }
}

def allocateBlocksToBatch(batchTime: Time): Unit = synchronized {
  if (lastAllocatedBatchTime== null|| batchTime > lastAllocatedBatchTime) {
    val streamIdToBlocks = streamIds.map { streamId =>
        (streamId, getReceivedBlockQueue(streamId).dequeueAll(x =>true))
    }.toMap
    val allocatedBlocks =AllocatedBlocks(streamIdToBlocks)
    if (writeToLog(BatchAllocationEvent(batchTime, allocatedBlocks))) {
      timeToAllocatedBlocks.put(batchTime, allocatedBlocks)
      lastAllocatedBatchTime = batchTime
    } else {
      logInfo(s"Possibly processed batch$batchTime need to be processed again in WAL recovery")
    }
  } else {
    // This situation occurs when:
    // 1. WAL is ended with BatchAllocationEvent, but without BatchCleanupEvent,
    // possibly processed batch job or half-processed batch job need to be processed again,
    // so the batchTime will be equal to lastAllocatedBatchTime.
    // 2. Slow checkpointing makes recovered batch time older than WAL recovered
    // lastAllocatedBatchTime.
    // This situation will only occurs in recovery time.
    logInfo(s"Possibly processed batch$batchTime need to be processed again in WAL recovery")
  }
}

ReceiverSupervisorImpl.scala

 

private valendpoint = env.rpcEnv.setupEndpoint(
  "Receiver-" +streamId +"-" + System.currentTimeMillis(),new ThreadSafeRpcEndpoint {
    override val rpcEnv: RpcEnv = env.rpcEnv

receive

override defreceive: PartialFunction[Any, Unit] = {
  case StopReceiver =>
    logInfo("Received stop signal")
    ReceiverSupervisorImpl.this.stop("Stopped by driver", None)
  case CleanupOldBlocks(threshTime) =>
    logDebug("Received delete old batch signal")
    cleanupOldBlocks(threshTime)
  case UpdateRateLimit(eps) =>
    logInfo(s"Received a new rate limit:$eps.")
    registeredBlockGenerators.foreach { bg =>
      bg.updateRate(eps)
    }
}

private[receiver]def updateRate(newRate: Long): Unit =
  if (newRate >0) {
    if (maxRateLimit> 0) {

//限制每个记录流进的速度
      rateLimiter.setRate(newRate.min(maxRateLimit))
    } else {
      rateLimiter.setRate(newRate)
    }
  }

public final voidsetRate(doublepermitsPerSecond) {
    Preconditions.checkArgument(permitsPerSecond > 0.0D && !Double.isNaN(permitsPerSecond), "rate must be positive");
    Object var3 = this.mutex;
    synchronized(this.mutex) {
        this.resync(this.readSafeMicros());
        double stableIntervalMicros = (double)TimeUnit.SECONDS.toMicros(1L) / permitsPerSecond;
        this.stableIntervalMicros = stableIntervalMicros;
        this.doSetRate(permitsPerSecond, stableIntervalMicros);
    }
}

ReceiverSupervisorI

/** Mark the supervisor and the receiver for stopping */
def stop(message:String, error: Option[Throwable]) {
  stoppingError = error.orNull
  stopReceiver(message, error)
  onStop(message, error)
  futureExecutionContext.shutdownNow()
  stopLatch.countDown()
}

 

/** Stop receiver */
def stopReceiver(message:String, error: Option[Throwable]): Unit = synchronized {
  try {
    logInfo("Stopping receiver with message: "+ message + ": "+ error.getOrElse(""))
    receiverState match{
      case Initialized=>
        logWarning("Skip stopping receiver because it has not yet stared")
      case Started=>
        receiverState =Stopped
        receiver.onStop()
        logInfo("Called receiver onStop")
        onReceiverStop(message, error)
      case Stopped=>
        logWarning("Receiver has been stopped")
    }
  } catch {
    case NonFatal(t) =>
      logError("Error stopping receiver "+ streamId+ t.getStackTraceString)
  }
}

子类实现

override protected defonReceiverStop(message: String, error: Option[Throwable]) {
  logInfo("Deregistering receiver " + streamId)
  val errorString = error.map(Throwables.getStackTraceAsString).getOrElse("")
  trackerEndpoint.askWithRetry[Boolean](DeregisterReceiver(streamId, message, errorString))
  logInfo("Stopped receiver " +streamId)
}