[GitHub] spark pull request #12154: [SPARK-12133][STREAMING] Streaming dynamic alloca...

[alunarbeach <gi...@git.apache.org>]

Github user alunarbeach commented on a diff in the pull request:

    https://github.com/apache/spark/pull/12154#discussion_r99911965
  
    --- Diff: streaming/src/main/scala/org/apache/spark/streaming/scheduler/ExecutorAllocationManager.scala ---
    @@ -0,0 +1,217 @@
    +/*
    + * Licensed to the Apache Software Foundation (ASF) under one or more
    + * contributor license agreements.  See the NOTICE file distributed with
    + * this work for additional information regarding copyright ownership.
    + * The ASF licenses this file to You under the Apache License, Version 2.0
    + * (the "License"); you may not use this file except in compliance with
    + * the License.  You may obtain a copy of the License at
    + *
    + *    http://www.apache.org/licenses/LICENSE-2.0
    + *
    + * Unless required by applicable law or agreed to in writing, software
    + * distributed under the License is distributed on an "AS IS" BASIS,
    + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    + * See the License for the specific language governing permissions and
    + * limitations under the License.
    + */
    +
    +
    +package org.apache.spark.streaming.scheduler
    +
    +import scala.util.Random
    +
    +import org.apache.spark.{ExecutorAllocationClient, SparkConf}
    +import org.apache.spark.internal.Logging
    +import org.apache.spark.streaming.util.RecurringTimer
    +import org.apache.spark.util.{Clock, Utils}
    +
    +/**
    + * Class that manages executor allocated to a StreamingContext, and dynamically request or kill
    + * executors based on the statistics of the streaming computation. At a high level, the policy is:
    + * - Use StreamingListener interface get batch processing times of completed batches
    + * - Periodically take the average batch completion times and compare with the batch interval
    + * - If (avg. proc. time / batch interval) >= scaling up ratio, then request more executors
    + * - If (avg. proc. time / batch interval) <= scaling down ratio, then try to kill a executor that
    + *   is not running a receiver
    + */
    +private[streaming] class ExecutorAllocationManager(
    +    client: ExecutorAllocationClient,
    +    receiverTracker: ReceiverTracker,
    +    conf: SparkConf,
    +    batchDurationMs: Long,
    +    clock: Clock) extends StreamingListener with Logging {
    +
    +  import ExecutorAllocationManager._
    +
    +  private val scalingIntervalSecs = conf.getTimeAsSeconds(
    +    SCALING_INTERVAL_KEY,
    +    s"${SCALING_INTERVAL_DEFAULT_SECS}s")
    +  private val scalingUpRatio = conf.getDouble(SCALING_UP_RATIO_KEY, SCALING_UP_RATIO_DEFAULT)
    +  private val scalingDownRatio = conf.getDouble(SCALING_DOWN_RATIO_KEY, SCALING_DOWN_RATIO_DEFAULT)
    +  private val minNumExecutors = conf.getInt(
    +    MIN_EXECUTORS_KEY,
    +    math.max(1, receiverTracker.numReceivers))
    +  private val maxNumExecutors = conf.getInt(MAX_EXECUTORS_KEY, Integer.MAX_VALUE)
    +  private val timer = new RecurringTimer(clock, scalingIntervalSecs * 1000,
    +    _ => manageAllocation(), "streaming-executor-allocation-manager")
    +
    +  @volatile private var batchProcTimeSum = 0L
    +  @volatile private var batchProcTimeCount = 0
    +
    +  validateSettings()
    +
    +  def start(): Unit = {
    +    timer.start()
    +    logInfo(s"ExecutorAllocationManager started with " +
    +      s"ratios = [$scalingUpRatio, $scalingDownRatio] and interval = $scalingIntervalSecs sec")
    +  }
    +
    +  def stop(): Unit = {
    +    timer.stop(interruptTimer = true)
    +    logInfo("ExecutorAllocationManager stopped")
    +  }
    +
    +  private def manageAllocation(): Unit = synchronized {
    +    logInfo(s"Managing executor allocation with ratios = [$scalingUpRatio, $scalingDownRatio]")
    +    if (batchProcTimeCount > 0) {
    +      val averageBatchProcTime = batchProcTimeSum / batchProcTimeCount
    +      val ratio = averageBatchProcTime.toDouble / batchDurationMs
    +      logInfo(s"Average: $averageBatchProcTime, ratio = $ratio" )
    +      if (ratio >= scalingUpRatio) {
    +        logDebug("Requesting executors")
    +        val numNewExecutors = math.max(math.round(ratio).toInt, 1)
    +        requestExecutors(numNewExecutors)
    +      } else if (ratio <= scalingDownRatio) {
    +        logDebug("Killing executors")
    +        killExecutor()
    +      }
    +    }
    +    batchProcTimeSum = 0
    +    batchProcTimeCount = 0
    +  }
    +
    +  private def requestExecutors(numNewExecutors: Int): Unit = {
    +    require(numNewExecutors >= 1)
    +    val allExecIds = client.getExecutorIds()
    +    logDebug(s"Executors (${allExecIds.size}) = ${allExecIds}")
    +    val targetTotalExecutors =
    +      math.max(math.min(maxNumExecutors, allExecIds.size + numNewExecutors), minNumExecutors)
    +    client.requestTotalExecutors(targetTotalExecutors, 0, Map.empty)
    +    logInfo(s"Requested total $targetTotalExecutors executors")
    +  }
    +
    +  private def killExecutor(): Unit = {
    +    val allExecIds = client.getExecutorIds()
    +    logDebug(s"Executors (${allExecIds.size}) = ${allExecIds}")
    +
    +    if (allExecIds.nonEmpty && allExecIds.size > minNumExecutors) {
    +      val execIdsWithReceivers = receiverTracker.getAllocatedExecutors.values.flatten.toSeq
    +      logInfo(s"Executors with receivers (${execIdsWithReceivers.size}): ${execIdsWithReceivers}")
    +
    +      val removableExecIds = allExecIds.diff(execIdsWithReceivers)
    +      logDebug(s"Removable executors (${removableExecIds.size}): ${removableExecIds}")
    +      if (removableExecIds.nonEmpty) {
    +        val execIdToRemove = removableExecIds(Random.nextInt(removableExecIds.size))
    +        client.killExecutor(execIdToRemove)
    +        logInfo(s"Requested to kill executor $execIdToRemove")
    +      } else {
    +        logInfo(s"No non-receiver executors to kill")
    +      }
    +    } else {
    +      logInfo("No available executor to kill")
    +    }
    +  }
    +
    +  private def addBatchProcTime(timeMs: Long): Unit = synchronized {
    +    batchProcTimeSum += timeMs
    +    batchProcTimeCount += 1
    +    logDebug(
    +      s"Added batch processing time $timeMs, sum = $batchProcTimeSum, count = $batchProcTimeCount")
    +  }
    +
    +  private def validateSettings(): Unit = {
    +    require(
    +      scalingIntervalSecs > 0,
    +      s"Config $SCALING_INTERVAL_KEY must be more than 0")
    +
    +    require(
    +      scalingUpRatio > 0,
    +      s"Config $SCALING_UP_RATIO_KEY must be more than 0")
    +
    +    require(
    +      scalingDownRatio > 0,
    +      s"Config $SCALING_DOWN_RATIO_KEY must be more than 0")
    +
    +    require(
    +      minNumExecutors > 0,
    +      s"Config $MIN_EXECUTORS_KEY must be more than 0")
    +
    +    require(
    +      maxNumExecutors > 0,
    +      s"$MAX_EXECUTORS_KEY must be more than 0")
    +
    +    require(
    +      scalingUpRatio > scalingDownRatio,
    +      s"Config $SCALING_UP_RATIO_KEY must be more than config $SCALING_DOWN_RATIO_KEY")
    +
    +    if (conf.contains(MIN_EXECUTORS_KEY) && conf.contains(MAX_EXECUTORS_KEY)) {
    +      require(
    +        maxNumExecutors >= minNumExecutors,
    +        s"Config $MAX_EXECUTORS_KEY must be more than config $MIN_EXECUTORS_KEY")
    +    }
    +  }
    +
    +  override def onBatchCompleted(batchCompleted: StreamingListenerBatchCompleted): Unit = {
    +    logDebug("onBatchCompleted called: " + batchCompleted)
    +    if (!batchCompleted.batchInfo.outputOperationInfos.values.exists(_.failureReason.nonEmpty)) {
    +      batchCompleted.batchInfo.processingDelay.foreach(addBatchProcTime)
    +    }
    +  }
    +}
    +
    +private[streaming] object ExecutorAllocationManager extends Logging {
    +  val ENABLED_KEY = "spark.streaming.dynamicAllocation.enabled"
    +
    +  val SCALING_INTERVAL_KEY = "spark.streaming.dynamicAllocation.scalingInterval"
    +  val SCALING_INTERVAL_DEFAULT_SECS = 60
    +
    +  val SCALING_UP_RATIO_KEY = "spark.streaming.dynamicAllocation.scalingUpRatio"
    +  val SCALING_UP_RATIO_DEFAULT = 0.9
    +
    +  val SCALING_DOWN_RATIO_KEY = "spark.streaming.dynamicAllocation.scalingDownRatio"
    +  val SCALING_DOWN_RATIO_DEFAULT = 0.3
    +
    +  val MIN_EXECUTORS_KEY = "spark.streaming.dynamicAllocation.minExecutors"
    +
    +  val MAX_EXECUTORS_KEY = "spark.streaming.dynamicAllocation.maxExecutors"
    --- End diff --
    
    @tdas Is there any particular reason, why initExecutors is not supported in streaming.dynamicAllocation?


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