Ngone51 commented on a change in pull request #30312:
URL: https://github.com/apache/spark/pull/30312#discussion_r522212744
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File path: core/src/main/scala/org/apache/spark/shuffle/ShuffleWriter.scala
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@@ -17,18 +17,466 @@
package org.apache.spark.shuffle
-import java.io.IOException
+import java.io.{File, IOException}
+import java.net.ConnectException
+import java.nio.ByteBuffer
+import java.util.concurrent.ExecutorService
+import scala.collection.mutable.{ArrayBuffer, HashMap, HashSet, Queue}
+
+import com.google.common.base.Throwables
+
+import org.apache.spark.{ShuffleDependency, SparkConf, SparkEnv}
+import org.apache.spark.annotation.Since
+import org.apache.spark.internal.Logging
+import org.apache.spark.internal.config._
+import org.apache.spark.launcher.SparkLauncher
+import org.apache.spark.network.buffer.{FileSegmentManagedBuffer,
ManagedBuffer, NioManagedBuffer}
+import org.apache.spark.network.netty.SparkTransportConf
+import org.apache.spark.network.shuffle.{BlockFetchingListener,
BlockStoreClient}
+import org.apache.spark.network.shuffle.ErrorHandler.BlockPushErrorHandler
+import org.apache.spark.network.util.TransportConf
import org.apache.spark.scheduler.MapStatus
+import org.apache.spark.shuffle.ShuffleWriter._
+import org.apache.spark.storage.{BlockId, BlockManagerId, ShufflePushBlockId}
+import org.apache.spark.util.{ThreadUtils, Utils}
/**
- * Obtained inside a map task to write out records to the shuffle system.
+ * Obtained inside a map task to write out records to the shuffle system, and
optionally
+ * initiate the block push process to remote shuffle services if push based
shuffle is enabled.
*/
-private[spark] abstract class ShuffleWriter[K, V] {
+private[spark] abstract class ShuffleWriter[K, V] extends Logging {
+ private[this] var maxBytesInFlight = 0L
+ private[this] var maxReqsInFlight = 0
+ private[this] var maxBlocksInFlightPerAddress = 0
+ private[this] var bytesInFlight = 0L
+ private[this] var reqsInFlight = 0
+ private[this] val numBlocksInFlightPerAddress = new HashMap[BlockManagerId,
Int]()
+ private[this] val deferredPushRequests = new HashMap[BlockManagerId,
Queue[PushRequest]]()
+ private[this] val pushRequests = new Queue[PushRequest]
+ private[this] val errorHandler = createErrorHandler()
+ private[this] val unreachableBlockMgrs = new HashSet[BlockManagerId]()
+
/** Write a sequence of records to this task's output */
@throws[IOException]
def write(records: Iterator[Product2[K, V]]): Unit
/** Close this writer, passing along whether the map completed */
def stop(success: Boolean): Option[MapStatus]
+
+ def getPartitionLengths(): Array[Long]
+
+ // VisibleForTesting
+ private[shuffle] def createErrorHandler(): BlockPushErrorHandler = {
+ new BlockPushErrorHandler() {
+ // For a connection exception against a particular host, we will stop
pushing any
+ // blocks to just that host and continue push blocks to other hosts. So,
here push of
+ // all blocks will only stop when it is "Too Late". Also see
updateStateAndCheckIfPushMore.
+ override def shouldRetryError(t: Throwable): Boolean = {
+ // If the block is too late, there is no need to retry it
+
!Throwables.getStackTraceAsString(t).contains(BlockPushErrorHandler.TOO_LATE_MESSAGE_SUFFIX)
+ }
+ }
+ }
+
+ /**
+ * Initiate the block push process. This will be invoked after the shuffle
writer
+ * finishes writing the shuffle file if push based shuffle is enabled.
+ *
+ * @param resolver block resolver used to locate mapper generated
shuffle file
+ * @param partitionLengths array of shuffle block size so we can tell
shuffle block
+ * boundaries within the shuffle file
+ * @param dep shuffle dependency to get shuffle ID and the
location of remote shuffle
+ * services to push local shuffle blocks
+ * @param partitionId map index of the shuffle map task
+ * @param mapId mapId of the shuffle map task
+ * @param conf spark configuration
+ */
+ def initiateBlockPush(
+ resolver: IndexShuffleBlockResolver,
+ partitionLengths: Array[Long],
+ dep: ShuffleDependency[_, _, _],
+ partitionId: Int,
+ mapId: Long,
+ conf: SparkConf): Unit = {
+ val numPartitions = dep.partitioner.numPartitions
+ val dataFile = resolver.getDataFile(dep.shuffleId, mapId)
+ val transportConf = SparkTransportConf.fromSparkConf(conf, "shuffle")
+
+ val maxBlockSizeToPush = conf.get(PUSH_SHUFFLE_MAX_BLOCK_SIZE_TO_PUSH) *
1024
+ val maxBlockBatchSize = conf.get(PUSH_SHUFFLE_MAX_BLOCK_BATCH_SIZE) * 1024
* 1024
+ val mergerLocs = dep.getMergerLocs.map(loc =>
+ BlockManagerId("", loc.host, loc.port))
+
+ maxBytesInFlight = conf.getSizeAsMb("spark.reducer.maxSizeInFlight",
"48m") * 1024 * 1024
+ maxReqsInFlight = conf.getInt("spark.reducer.maxReqsInFlight",
Int.MaxValue)
+ maxBlocksInFlightPerAddress =
conf.get(REDUCER_MAX_BLOCKS_IN_FLIGHT_PER_ADDRESS)
+
+ val requests = prepareBlockPushRequests(numPartitions, partitionId,
dep.shuffleId, dataFile,
+ partitionLengths, mergerLocs, transportConf, maxBlockSizeToPush,
maxBlockBatchSize)
+ // Randomize the orders of the PushRequest, so different mappers pushing
blocks at the same
+ // time won't be pushing the same ranges of shuffle partitions.
+ pushRequests ++= Utils.randomize(requests)
+
+ val shuffleClient = SparkEnv.get.blockManager.blockStoreClient
+ submitTask(() => {
+ pushUpToMax(shuffleClient)
+ })
+ }
+
+ /**
+ * Triggers the push. It's a separate method for testing.
+ * VisibleForTesting
+ */
+ protected def submitTask(task: Runnable): Unit = {
+ if (BLOCK_PUSHER_POOL != null) {
+ BLOCK_PUSHER_POOL.execute(task)
+ }
+ }
+
+ /**
+ * Since multiple netty client threads could potentially be calling
pushUpToMax for the same
+ * mapper, we synchronize access to this method so that only one thread can
push blocks for
+ * a given mapper. This helps to simplify access to the shared states. The
down side of this
+ * is that we could unnecessarily block other mappers' block pushes if all
netty client threads
+ * are occupied by block pushes from the same mapper.
+ *
+ * This code is similar to ShuffleBlockFetcherIterator#fetchUpToMaxBytes in
how it throttles
+ * the data transfer between shuffle client/server.
+ */
+ private def pushUpToMax(shuffleClient: BlockStoreClient): Unit =
synchronized {
+ // Process any outstanding deferred push requests if possible.
+ if (deferredPushRequests.nonEmpty) {
+ for ((remoteAddress, defReqQueue) <- deferredPushRequests) {
+ while (isRemoteBlockPushable(defReqQueue) &&
+ !isRemoteAddressMaxedOut(remoteAddress, defReqQueue.front)) {
+ val request = defReqQueue.dequeue()
+ logDebug(s"Processing deferred push request for $remoteAddress with "
+ + s"${request.blocks.length} blocks")
+ sendRequest(request, shuffleClient)
+ if (defReqQueue.isEmpty) {
+ deferredPushRequests -= remoteAddress
+ }
+ }
+ }
+ }
+
+ // Process any regular push requests if possible.
+ while (isRemoteBlockPushable(pushRequests)) {
+ val request = pushRequests.dequeue()
+ val remoteAddress = request.address
+ if (isRemoteAddressMaxedOut(remoteAddress, request)) {
+ logDebug(s"Deferring push request for $remoteAddress with
${request.blocks.size} blocks")
+ val defReqQueue = deferredPushRequests.getOrElse(remoteAddress, new
Queue[PushRequest]())
+ defReqQueue.enqueue(request)
+ deferredPushRequests(remoteAddress) = defReqQueue
+ } else {
+ sendRequest(request, shuffleClient)
+ }
+ }
+
+ def isRemoteBlockPushable(pushReqQueue: Queue[PushRequest]): Boolean = {
+ pushReqQueue.nonEmpty &&
+ (bytesInFlight == 0 ||
+ (reqsInFlight + 1 <= maxReqsInFlight &&
+ bytesInFlight + pushReqQueue.front.size <= maxBytesInFlight))
+ }
+
+ // Checks if sending a new push request will exceed the max no. of blocks
being pushed to a
+ // given remote address.
+ def isRemoteAddressMaxedOut(remoteAddress: BlockManagerId, request:
PushRequest): Boolean = {
+ (numBlocksInFlightPerAddress.getOrElse(remoteAddress, 0)
+ + request.blocks.size) > maxBlocksInFlightPerAddress
+ }
+ }
+
+ /**
+ * Push blocks to remote shuffle server. The callback listener will invoke
#pushUpToMax again
+ * to trigger pushing the next batch of blocks once some block transfer is
done in the current
+ * batch. This way, we decouple the map task from the block push process,
since it is netty
+ * client thread instead of task execution thread which takes care of
majority of the block
+ * pushes.
+ */
+ private def sendRequest(request: PushRequest, shuffleClient:
BlockStoreClient): Unit = {
+ bytesInFlight = bytesInFlight + request.size
+ reqsInFlight = reqsInFlight + 1
+ numBlocksInFlightPerAddress(request.address) =
numBlocksInFlightPerAddress.getOrElseUpdate(
+ request.address, 0) + request.blocks.length
+
+ val sizeMap = request.blocks.map { case (blockId, size) =>
(blockId.toString, size) }.toMap
+ val address = request.address
+ val blockIds = request.blocks.map(_._1.toString)
+ val remainingBlocks = new HashSet[String]() ++= blockIds
+
+ val blockPushListener = new BlockFetchingListener {
+ // Initiating a connection and pushing blocks to a remote shuffle
service is always handled by
+ // the block-push-threads. We should not initiate the connection
creation in the
+ // blockPushListener callbacks which are invoked by the netty eventloop
because:
+ // 1. TrasportClient.createConnection(...) blocks for connection to be
established and it's
+ // recommended to avoid any blocking operations in the eventloop;
+ // 2. The actual connection creation is a task that gets added to the
task queue of another
+ // eventloop which could have eventloops eventually blocking each other.
+ // Once the blockPushListener is notified of the block push success or
failure, we
+ // just delegate it to block-push-threads.
+ def handleResult(result: PushResult): Unit = {
+ submitTask(() => {
+ if (updateStateAndCheckIfPushMore(
+ sizeMap(result.blockId), address, remainingBlocks, result)) {
+ pushUpToMax(SparkEnv.get.blockManager.blockStoreClient)
+ }
+ })
+ }
+
+ override def onBlockFetchSuccess(blockId: String, data: ManagedBuffer):
Unit = {
+ logTrace(s"Push for block $blockId to $address successful.")
+ handleResult(PushResult(blockId, null))
+ }
+
+ override def onBlockFetchFailure(blockId: String, exception: Throwable):
Unit = {
+ // check the message or it's cause to see it needs to be logged.
+ if (!errorHandler.shouldLogError(exception)) {
+ logTrace(s"Pushing block $blockId to $address failed.", exception)
+ } else {
+ logWarning(s"Pushing block $blockId to $address failed.", exception)
+ }
+ handleResult(PushResult(blockId, exception))
+ }
+ }
+ shuffleClient.pushBlocks(address.host, address.port, blockIds.toArray,
+ sliceReqBufferIntoBlockBuffers(request.reqBuffer,
request.blocks.map(_._2)),
+ blockPushListener)
+ }
+
+ /**
+ * Given the ManagedBuffer representing all the continuous blocks inside the
shuffle data file
+ * for a PushRequest and an array of individual block sizes, load the buffer
from disk into
+ * memory and slice it into multiple smaller buffers representing each block.
+ *
+ * With nio ByteBuffer, the individual block buffers share data with the
initial in memory
+ * buffer loaded from disk. Thus only one copy of the block data is kept in
memory.
+ * @param reqBuffer A {{FileSegmentManagedBuffer}} representing all the
continuous blocks in
+ * the shuffle data file for a PushRequest
+ * @param blockSizes Array of block sizes
+ * @return Array of in memory buffer for each individual block
+ */
+ private def sliceReqBufferIntoBlockBuffers(
+ reqBuffer: ManagedBuffer,
+ blockSizes: Seq[Long]): Array[ManagedBuffer] = {
+ if (blockSizes.size == 1) {
+ Seq(reqBuffer).toArray
+ } else {
+ val inMemoryBuffer = reqBuffer.nioByteBuffer()
+ val blockOffsets = new Array[Long](blockSizes.size)
+ var offset = 0L
+ for (index <- blockSizes.indices) {
+ blockOffsets(index) = offset
+ offset += blockSizes(index)
+ }
+ blockOffsets.zip(blockSizes).map {
+ case (offset, size) =>
+ new NioManagedBuffer(inMemoryBuffer.duplicate()
Review comment:
Would it be better to use `FileSegmentManagedBuffer` here in terms of
memory usage?
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