agrawaldevesh commented on a change in pull request #28708: URL: https://github.com/apache/spark/pull/28708#discussion_r439197120
########## File path: core/src/main/scala/org/apache/spark/storage/BlockManagerDecommissioner.scala ########## @@ -0,0 +1,265 @@ +/* + * 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 +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) + + private class ShuffleMigrationRunnable(peer: BlockManagerId) extends Runnable { + @volatile var running = true + override def run(): Unit = { + var migrating: Option[(Int, Long)] = 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 => + logInfo("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((shuffleId, mapId)) => + logInfo(s"Trying to migrate shuffle ${shuffleId},${mapId} to ${peer}") + val blocks = + bm.migratableResolver.getMigrationBlocks(shuffleId, mapId) + 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 + logInfo(s"Migrated sub block ${blockId}") + } + logInfo(s"Migrated ${shuffleId},${mapId} 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[(Int, Long)]() + + // Shuffles which are queued for migration + private[storage] val shufflesToMigrate = + new java.util.concurrent.ConcurrentLinkedQueue[(Int, Long)]() + + @volatile private var stopped = false + + private val migrationPeers = + mutable.HashMap[BlockManagerId, (ShuffleMigrationRunnable, ExecutorService)]() + + 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 = { + var failures = 0 + while (!stopped && !Thread.interrupted() && failures < 20) { + 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") + } + 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" + + "spark.storage.decommission.shuffle_blocks\n" + + "spark.storage.decommission.rdd_blocks") + } + 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) => + failures += 1 + logError("Error occurred while trying to replicate cached RDD blocks" + + s" for block manager decommissioning (failure count: $failures)", e) + } + } + } + } + + /** + * 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() + val newShufflesToMigrate = localShuffles.&~(migratingShuffles).toSeq + shufflesToMigrate.addAll(newShufflesToMigrate.asJava) + migratingShuffles ++= newShufflesToMigrate + + // Update the threads doing migrations + // TODO: Sort & only start as many threads as min(||blocks||, ||targets||) using location pref + val livePeerSet = bm.getPeers(false).toSet + val currentPeerSet = migrationPeers.keys.toSet + val deadPeers = currentPeerSet.&~(livePeerSet) + val newPeers = livePeerSet.&~(currentPeerSet) + migrationPeers ++= newPeers.map { peer => + logDebug(s"Starting thread to migrate shuffle blocks to ${peer}") + val executor = ThreadUtils.newDaemonSingleThreadExecutor(s"migrate-shuffle-to-${peer}") + val runnable = new ShuffleMigrationRunnable(peer) Review comment: This code tries to copy the shuffled blocks to one other peer (ie offloads to another live peer), by virtue of the fact that `shufflesToMigrate` is polled. This should be documented :-) Its quite subtle as it currently reads. Second, can we dedup this logic with the `replicate` codepath used for replicating `cached` blocks. The only semantic difference is wrt to you want to copy the block to one peer vs N peers (for replicate). The rest of the machinery should be shareable. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: reviews-unsubscr...@spark.apache.org For additional commands, e-mail: reviews-h...@spark.apache.org
