holdenk commented on a change in pull request #28708: URL: https://github.com/apache/spark/pull/28708#discussion_r445073751
########## File path: core/src/main/scala/org/apache/spark/storage/BlockManagerDecommissioner.scala ########## @@ -0,0 +1,280 @@ +/* + * 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.storage + +import java.util.concurrent.ExecutorService + +import scala.collection.JavaConverters._ +import scala.collection.mutable +import scala.util.control.NonFatal + +import org.apache.spark._ +import org.apache.spark.internal.Logging +import org.apache.spark.internal.config +import org.apache.spark.shuffle.{MigratableResolver, ShuffleBlockInfo} +import org.apache.spark.storage.BlockManagerMessages.ReplicateBlock +import org.apache.spark.util.ThreadUtils + +/** + * Class to handle block manager decommissioning retries. + * It creates a Thread to retry offloading all RDD cache and Shuffle blocks + */ +private[storage] class BlockManagerDecommissioner( + conf: SparkConf, + bm: BlockManager) extends Logging { + + private val maxReplicationFailuresForDecommission = + conf.get(config.STORAGE_DECOMMISSION_MAX_REPLICATION_FAILURE_PER_BLOCK) + + /** + * This runnable consumes any shuffle blocks in the queue for migration. This part of a + * producer/consumer where the main migration loop updates the queue of blocks to be migrated + * periodically. On migration failure, the current thread will reinsert the block for another + * thread to consume. Each thread migrates blocks to a different particular executor to avoid + * distribute the blocks as quickly as possible without overwhelming any particular executor. + * + * There is no preference for which peer a given block is migrated to. + * This is notable different than the RDD cache block migration (further down in this file) + * which uses the existing priority mechanism for determining where to replicate blocks to. + * Generally speaking cache blocks are less impactful as they normally represent narrow + * transformations and we normally have less cache present than shuffle data. + * + * The producer/consumer model is chosen for shuffle block migration to maximize + * the chance of migrating all shuffle blocks before the executor is forced to exit. + */ + private class ShuffleMigrationRunnable(peer: BlockManagerId) extends Runnable { + @volatile var running = true + override def run(): Unit = { + var migrating: Option[ShuffleBlockInfo] = None + logInfo(s"Starting migration thread for ${peer}") + // Once a block fails to transfer to an executor stop trying to transfer more blocks + try { + while (running && !Thread.interrupted()) { + val migrating = Option(shufflesToMigrate.poll()) + migrating match { + case None => + logDebug("Nothing to migrate") + // Nothing to do right now, but maybe a transfer will fail or a new block + // will finish being committed. + val SLEEP_TIME_SECS = 1 + Thread.sleep(SLEEP_TIME_SECS * 1000L) + case Some(shuffleBlockInfo) => + logInfo(s"Trying to migrate shuffle ${shuffleBlockInfo} to ${peer}") + val blocks = + bm.migratableResolver.getMigrationBlocks(shuffleBlockInfo) + logInfo(s"Got migration sub-blocks ${blocks}") + blocks.foreach { case (blockId, buffer) => + logInfo(s"Migrating sub-block ${blockId}") + bm.blockTransferService.uploadBlockSync( + peer.host, + peer.port, + peer.executorId, + blockId, + buffer, + StorageLevel.DISK_ONLY, + null)// class tag, we don't need for shuffle + logDebug(s"Migrated sub block ${blockId}") + } + logInfo(s"Migrated ${shuffleBlockInfo} to ${peer}") + } + } + // This catch is intentionally outside of the while running block. + // if we encounter errors migrating to an executor we want to stop. + } catch { + case e: Exception => + migrating match { + case Some(shuffleMap) => + logError(s"Error ${e} during migration, adding ${shuffleMap} back to migration queue") + shufflesToMigrate.add(shuffleMap) + case None => + logError(s"Error ${e} while waiting for block to migrate") + } + } + } + } + + // Shuffles which are either in queue for migrations or migrated + private val migratingShuffles = mutable.HashSet[ShuffleBlockInfo]() + + // Shuffles which are queued for migration + private[storage] val shufflesToMigrate = + new java.util.concurrent.ConcurrentLinkedQueue[ShuffleBlockInfo]() + + @volatile private var stopped = false + + private val migrationPeers = + mutable.HashMap[BlockManagerId, ShuffleMigrationRunnable]() + + private lazy val blockMigrationExecutor = + ThreadUtils.newDaemonSingleThreadExecutor("block-manager-decommission") + + private val blockMigrationRunnable = new Runnable { + val sleepInterval = conf.get(config.STORAGE_DECOMMISSION_REPLICATION_REATTEMPT_INTERVAL) + + override def run(): Unit = { + if (!conf.get(config.STORAGE_RDD_DECOMMISSION_ENABLED) && + !conf.get(config.STORAGE_SHUFFLE_DECOMMISSION_ENABLED)) { + logWarning("Decommissioning, but no task configured set one or both:\n" + + s"${config.STORAGE_RDD_DECOMMISSION_ENABLED.key}\n" + + s"${config.STORAGE_SHUFFLE_DECOMMISSION_ENABLED.key}") + stopped = true + } + while (!stopped && !Thread.interrupted()) { + logInfo("Iterating on migrating from the block manager.") + try { + // If enabled we migrate shuffle blocks first as they are more expensive. + if (conf.get(config.STORAGE_SHUFFLE_DECOMMISSION_ENABLED)) { + logDebug("Attempting to replicate all shuffle blocks") + offloadShuffleBlocks() + logInfo("Done starting workers to migrate shuffle blocks") + } + if (conf.get(config.STORAGE_RDD_DECOMMISSION_ENABLED)) { + logDebug("Attempting to replicate all cached RDD blocks") + decommissionRddCacheBlocks() + logInfo("Attempt to replicate all cached blocks done") + } + logInfo(s"Waiting for ${sleepInterval} before refreshing migrations.") + Thread.sleep(sleepInterval) + } catch { + case e: InterruptedException => + logInfo("Interrupted during migration, will not refresh migrations.") + stopped = true + case NonFatal(e) => + logError("Error occurred while trying to replicate for block manager decommissioning.", + e) + stopped = true + } + } + } + } + + lazy val shuffleMigrationPool = ThreadUtils.newDaemonCachedThreadPool( + "migrate-shuffles", + conf.get(config.STORAGE_SHUFFLE_DECOMMISSION_MAX_THREADS)) + /** + * Tries to offload all shuffle blocks that are registered with the shuffle service locally. + * Note: this does not delete the shuffle files in-case there is an in-progress fetch + * but rather shadows them. + * Requires an Indexed based shuffle resolver. + * Note: if called in testing please call stopOffloadingShuffleBlocks to avoid thread leakage. + */ + private[storage] def offloadShuffleBlocks(): Unit = { + // Update the queue of shuffles to be migrated + logInfo("Offloading shuffle blocks") + val localShuffles = bm.migratableResolver.getStoredShuffles() Review comment: Also to clarify: this race condition is OK here in this PR as well since we just re-run it until the executor is killed so no worries about missing files. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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