diff --git a/src/scala/spark/HttpBlockedLocalFileShuffle.scala b/src/scala/spark/HttpBlockedLocalFileShuffle.scala
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+++ b/src/scala/spark/HttpBlockedLocalFileShuffle.scala
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+package spark
+
+import java.io._
+import java.net._
+import java.util.{BitSet, Random, Timer, TimerTask, UUID}
+import java.util.concurrent.atomic.AtomicLong
+import java.util.concurrent.{Executors, ThreadPoolExecutor, ThreadFactory}
+
+import scala.collection.mutable.{ArrayBuffer, HashMap}
+
+
+/**
+ * An implementation of shuffle using local files served through HTTP where
+ * receivers create simultaneous connections to multiple servers by setting the
+ * 'spark.blockedLocalFileShuffle.maxConnections' config option.
+ *
+ * By controlling the 'spark.blockedLocalFileShuffle.blockSize' config option
+ * one can also control the largest block size to divide each map output into.
+ * Essentially, instead of creating one large output file for each reducer, maps
+ * create multiple smaller files to enable finer level of engagement.
+ *
+ * TODO: Add support for compression when spark.compress is set to true.
+ */
+@serializable
+class HttpBlockedLocalFileShuffle[K, V, C] extends Shuffle[K, V, C] with Logging {
+ @transient var totalSplits = 0
+ @transient var hasSplits = 0
+
+ @transient var blocksInSplit: Array[ArrayBuffer[Long]] = null
+ @transient var totalBlocksInSplit: Array[Int] = null
+ @transient var hasBlocksInSplit: Array[Int] = null
+
+ @transient var hasSplitsBitVector: BitSet = null
+ @transient var splitsInRequestBitVector: BitSet = null
+
+ @transient var combiners: HashMap[K,C] = null
+
+ override def compute(input: RDD[(K, V)],
+ numOutputSplits: Int,
+ createCombiner: V => C,
+ mergeValue: (C, V) => C,
+ mergeCombiners: (C, C) => C)
+ : RDD[(K, C)] =
+ {
+ val sc = input.sparkContext
+ val shuffleId = HttpBlockedLocalFileShuffle.newShuffleId()
+ logInfo("Shuffle ID: " + shuffleId)
+
+ val splitRdd = new NumberedSplitRDD(input)
+ val numInputSplits = splitRdd.splits.size
+
+ // Run a parallel map and collect to write the intermediate data files,
+ // returning a list of inputSplitId -> serverUri pairs
+ val outputLocs = splitRdd.map((pair: (Int, Iterator[(K, V)])) => {
+ val myIndex = pair._1
+ val myIterator = pair._2
+ val buckets = Array.tabulate(numOutputSplits)(_ => new HashMap[K, C])
+ for ((k, v) <- myIterator) {
+ var bucketId = k.hashCode % numOutputSplits
+ if (bucketId < 0) { // Fix bucket ID if hash code was negative
+ bucketId += numOutputSplits
+ }
+ val bucket = buckets(bucketId)
+ bucket(k) = bucket.get(k) match {
+ case Some(c) => mergeValue(c, v)
+ case None => createCombiner(v)
+ }
+ }
+
+ for (i <- 0 until numOutputSplits) {
+ // Open the INDEX file
+ var indexFile: File =
+ HttpBlockedLocalFileShuffle.getBlockIndexOutputFile(shuffleId, myIndex, i)
+ var indexOut = new ObjectOutputStream(new FileOutputStream(indexFile))
+ var indexDirty: Boolean = true
+ var alreadyWritten: Long = 0
+
+ // Open the actual file
+ var file: File =
+ HttpBlockedLocalFileShuffle.getOutputFile(shuffleId, myIndex, i)
+ val out = new ObjectOutputStream(new FileOutputStream(file))
+
+ val writeStartTime = System.currentTimeMillis
+ logInfo("BEGIN WRITE: " + file)
+
+ buckets(i).foreach(pair => {
+ out.writeObject(pair)
+ out.flush()
+ indexDirty = true
+
+ // Update the INDEX file if more than blockSize limit has been written
+ if (file.length - alreadyWritten > HttpBlockedLocalFileShuffle.BlockSize) {
+ indexOut.writeObject(file.length)
+ indexDirty = false
+ alreadyWritten = file.length
+ }
+ })
+
+ // Write down the last range if it was not written
+ if (indexDirty) {
+ indexOut.writeObject(file.length)
+ }
+
+ out.close()
+ indexOut.close()
+
+ logInfo("END WRITE: " + file)
+ val writeTime = (System.currentTimeMillis - writeStartTime)
+ logInfo("Writing " + file + " of size " + file.length + " bytes took " + writeTime + " millis.")
+ }
+
+ (myIndex, HttpBlockedLocalFileShuffle.serverUri)
+ }).collect()
+
+ // TODO: Could broadcast outputLocs
+
+ // Return an RDD that does each of the merges for a given partition
+ val indexes = sc.parallelize(0 until numOutputSplits, numOutputSplits)
+ return indexes.flatMap((myId: Int) => {
+ totalSplits = outputLocs.size
+ hasSplits = 0
+
+ blocksInSplit = Array.tabulate(totalSplits)(_ => new ArrayBuffer[Long])
+ totalBlocksInSplit = Array.tabulate(totalSplits)(_ => -1)
+ hasBlocksInSplit = Array.tabulate(totalSplits)(_ => 0)
+
+ hasSplitsBitVector = new BitSet(totalSplits)
+ splitsInRequestBitVector = new BitSet(totalSplits)
+
+ combiners = new HashMap[K, C]
+
+ var threadPool = HttpBlockedLocalFileShuffle.newDaemonFixedThreadPool(
+ HttpBlockedLocalFileShuffle.MaxConnections)
+
+ while (hasSplits < totalSplits) {
+ var numThreadsToCreate =
+ Math.min(totalSplits, HttpBlockedLocalFileShuffle.MaxConnections) -
+ threadPool.getActiveCount
+
+ while (hasSplits < totalSplits && numThreadsToCreate > 0) {
+ // Select a random split to pull
+ val splitIndex = selectRandomSplit
+
+ if (splitIndex != -1) {
+ val (inputId, serverUri) = outputLocs(splitIndex)
+
+ threadPool.execute(new ShuffleClient(serverUri, shuffleId.toInt,
+ inputId, myId, splitIndex, mergeCombiners))
+
+ // splitIndex is in transit. Will be unset in the ShuffleClient
+ splitsInRequestBitVector.synchronized {
+ splitsInRequestBitVector.set(splitIndex)
+ }
+ }
+
+ numThreadsToCreate = numThreadsToCreate - 1
+ }
+
+ // Sleep for a while before creating new threads
+ Thread.sleep(HttpBlockedLocalFileShuffle.MinKnockInterval)
+ }
+ combiners
+ })
+ }
+
+ def selectRandomSplit: Int = {
+ var requiredSplits = new ArrayBuffer[Int]
+
+ synchronized {
+ for (i <- 0 until totalSplits) {
+ if (!hasSplitsBitVector.get(i) && !splitsInRequestBitVector.get(i)) {
+ requiredSplits += i
+ }
+ }
+ }
+
+ if (requiredSplits.size > 0) {
+ requiredSplits(HttpBlockedLocalFileShuffle.ranGen.nextInt(
+ requiredSplits.size))
+ } else {
+ -1
+ }
+ }
+
+ class ShuffleClient(serverUri: String, shuffleId: Int,
+ inputId: Int, myId: Int, splitIndex: Int,
+ mergeCombiners: (C, C) => C)
+ extends Thread with Logging {
+ private var receptionSucceeded = false
+
+ override def run: Unit = {
+ try {
+ // First get the INDEX file if totalBlocksInSplit(inputId) is unknown
+ if (totalBlocksInSplit(inputId) == -1) {
+ val url = "%s/shuffle/%d/%d/INDEX-%d".format(serverUri, shuffleId,
+ inputId, myId)
+ val inputStream = new ObjectInputStream(new URL(url).openStream())
+
+ try {
+ while (true) {
+ blocksInSplit(inputId) +=
+ inputStream.readObject().asInstanceOf[Long]
+ }
+ } catch {
+ case e: EOFException => {}
+ }
+
+ totalBlocksInSplit(inputId) = blocksInSplit(inputId).size
+ inputStream.close()
+ }
+
+ val urlString =
+ "%s/shuffle/%d/%d/%d".format(serverUri, shuffleId, inputId, myId)
+ val url = new URL(urlString)
+ val httpConnection =
+ url.openConnection().asInstanceOf[HttpURLConnection]
+
+ // Set the range to download
+ val blockStartsAt = hasBlocksInSplit(inputId) match {
+ case 0 => 0
+ case _ => blocksInSplit(inputId)(hasBlocksInSplit(inputId) - 1) + 1
+ }
+ val blockEndsAt = blocksInSplit(inputId)(hasBlocksInSplit(inputId))
+ httpConnection.setRequestProperty("Range",
+ "bytes=" + blockStartsAt + "-" + blockEndsAt)
+
+ // Connect to the server
+ httpConnection.connect()
+
+ val urStringWithRange =
+ urlString + "[%d:%d]".format(blockStartsAt, blockEndsAt)
+ val readStartTime = System.currentTimeMillis
+ logInfo("BEGIN READ: " + urStringWithRange)
+
+ // Receive the block
+ val inputStream = new ObjectInputStream(httpConnection.getInputStream())
+ try {
+ while (true) {
+ val (k, c) = inputStream.readObject().asInstanceOf[(K, C)]
+ combiners.synchronized {
+ combiners(k) = combiners.get(k) match {
+ case Some(oldC) => mergeCombiners(oldC, c)
+ case None => c
+ }
+ }
+ }
+ } catch {
+ case e: EOFException => {}
+ }
+ inputStream.close()
+
+ logInfo("END READ: " + urStringWithRange)
+ val readTime = System.currentTimeMillis - readStartTime
+ logInfo("Reading " + urStringWithRange + " took " + readTime + " millis.")
+
+ // Disconnect
+ httpConnection.disconnect()
+
+ // Reception completed. Update stats.
+ hasBlocksInSplit(inputId) = hasBlocksInSplit(inputId) + 1
+
+ // Split has been received only if all the blocks have been received
+ if (hasBlocksInSplit(inputId) == totalBlocksInSplit(inputId)) {
+ hasSplitsBitVector.synchronized {
+ hasSplitsBitVector.set(splitIndex)
+ }
+ hasSplits += 1
+ }
+
+ // We have received splitIndex
+ splitsInRequestBitVector.synchronized {
+ splitsInRequestBitVector.set(splitIndex, false)
+ }
+
+ receptionSucceeded = true
+ } catch {
+ // EOFException is expected to happen because sender can break
+ // connection due to timeout
+ case eofe: java.io.EOFException => { }
+ case e: Exception => {
+ logInfo("ShuffleClient had a " + e)
+ }
+ } finally {
+ // If reception failed, unset for future retry
+ if (!receptionSucceeded) {
+ splitsInRequestBitVector.synchronized {
+ splitsInRequestBitVector.set(splitIndex, false)
+ }
+ }
+ }
+ }
+ }
+}
+
+object HttpBlockedLocalFileShuffle extends Logging {
+ // Used thoughout the code for small and large waits/timeouts
+ private var BlockSize_ = 1024 * 1024
+
+ private var MinKnockInterval_ = 1000
+ private var MaxKnockInterval_ = 5000
+
+ // Maximum number of connections
+ private var MaxConnections_ = 4
+
+ private var initialized = false
+ private var nextShuffleId = new AtomicLong(0)
+
+ // Variables initialized by initializeIfNeeded()
+ private var shuffleDir: File = null
+ private var server: HttpServer = null
+ private var serverUri: String = null
+
+ // Random number generator
+ var ranGen = new Random
+
+ private def initializeIfNeeded() = synchronized {
+ if (!initialized) {
+ // Load config parameters
+ BlockSize_ = System.getProperty(
+ "spark.blockedLocalFileShuffle.blockSize", "1024").toInt * 1024
+
+ MinKnockInterval_ = System.getProperty(
+ "spark.blockedLocalFileShuffle.minKnockInterval", "1000").toInt
+ MaxKnockInterval_ = System.getProperty(
+ "spark.blockedLocalFileShuffle.maxKnockInterval", "5000").toInt
+
+ MaxConnections_ = System.getProperty(
+ "spark.blockedLocalFileShuffle.maxConnections", "4").toInt
+
+ // TODO: localDir should be created by some mechanism common to Spark
+ // so that it can be shared among shuffle, broadcast, etc
+ val localDirRoot = System.getProperty("spark.local.dir", "/tmp")
+ var tries = 0
+ var foundLocalDir = false
+ var localDir: File = null
+ var localDirUuid: UUID = null
+ while (!foundLocalDir && tries < 10) {
+ tries += 1
+ try {
+ localDirUuid = UUID.randomUUID
+ localDir = new File(localDirRoot, "spark-local-" + localDirUuid)
+ if (!localDir.exists) {
+ localDir.mkdirs()
+ foundLocalDir = true
+ }
+ } catch {
+ case e: Exception =>
+ logWarning("Attempt " + tries + " to create local dir failed", e)
+ }
+ }
+ if (!foundLocalDir) {
+ logError("Failed 10 attempts to create local dir in " + localDirRoot)
+ System.exit(1)
+ }
+ shuffleDir = new File(localDir, "shuffle")
+ shuffleDir.mkdirs()
+ logInfo("Shuffle dir: " + shuffleDir)
+
+ val extServerPort = System.getProperty(
+ "spark.localFileShuffle.external.server.port", "-1").toInt
+ if (extServerPort != -1) {
+ // We're using an external HTTP server; set URI relative to its root
+ var extServerPath = System.getProperty(
+ "spark.localFileShuffle.external.server.path", "")
+ if (extServerPath != "" && !extServerPath.endsWith("/")) {
+ extServerPath += "/"
+ }
+ serverUri = "http://%s:%d/%s/spark-local-%s".format(
+ Utils.localIpAddress, extServerPort, extServerPath, localDirUuid)
+ } else {
+ // Create our own server
+ server = new HttpServer(localDir)
+ server.start()
+ serverUri = server.uri
+ }
+ initialized = true
+ logInfo("Local URI: " + serverUri)
+ }
+ }
+
+ def BlockSize = BlockSize_
+
+ def MinKnockInterval = MinKnockInterval_
+ def MaxKnockInterval = MaxKnockInterval_
+
+ def MaxConnections = MaxConnections_
+
+ def getOutputFile(shuffleId: Long, inputId: Int, outputId: Int): File = {
+ initializeIfNeeded()
+ val dir = new File(shuffleDir, shuffleId + "/" + inputId)
+ dir.mkdirs()
+ val file = new File(dir, "" + outputId)
+ return file
+ }
+
+ def getBlockIndexOutputFile(shuffleId: Long, inputId: Int,
+ outputId: Int): File = {
+ initializeIfNeeded()
+ val dir = new File(shuffleDir, shuffleId + "/" + inputId)
+ dir.mkdirs()
+ val file = new File(dir, "INDEX-" + outputId)
+ return file
+ }
+
+ def getServerUri(): String = {
+ initializeIfNeeded()
+ serverUri
+ }
+
+ def newShuffleId(): Long = {
+ nextShuffleId.getAndIncrement()
+ }
+
+ // Returns a standard ThreadFactory except all threads are daemons
+ private def newDaemonThreadFactory: ThreadFactory = {
+ new ThreadFactory {
+ def newThread(r: Runnable): Thread = {
+ var t = Executors.defaultThreadFactory.newThread(r)
+ t.setDaemon(true)
+ return t
+ }
+ }
+ }
+
+ // Wrapper over newFixedThreadPool
+ def newDaemonFixedThreadPool(nThreads: Int): ThreadPoolExecutor = {
+ var threadPool =
+ Executors.newFixedThreadPool(nThreads).asInstanceOf[ThreadPoolExecutor]
+
+ threadPool.setThreadFactory(newDaemonThreadFactory)
+
+ return threadPool
+ }
+}