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package spark.scheduler
import java.io._
import java.util.{HashMap => JHashMap}
import java.util.zip.{GZIPInputStream, GZIPOutputStream}
import scala.collection.mutable.{ArrayBuffer, HashMap}
import scala.collection.JavaConversions._
import it.unimi.dsi.fastutil.io.FastBufferedOutputStream
import com.ning.compress.lzf.LZFInputStream
import com.ning.compress.lzf.LZFOutputStream
import spark._
import spark.storage._
private[spark] object ShuffleMapTask {
// A simple map between the stage id to the serialized byte array of a task.
// Served as a cache for task serialization because serialization can be
// expensive on the master node if it needs to launch thousands of tasks.
val serializedInfoCache = new JHashMap[Int, Array[Byte]]
def serializeInfo(stageId: Int, rdd: RDD[_], dep: ShuffleDependency[_,_]): Array[Byte] = {
synchronized {
val old = serializedInfoCache.get(stageId)
if (old != null) {
return old
} else {
val out = new ByteArrayOutputStream
val ser = SparkEnv.get.closureSerializer.newInstance
val objOut = ser.serializeStream(new GZIPOutputStream(out))
objOut.writeObject(rdd)
objOut.writeObject(dep)
objOut.close()
val bytes = out.toByteArray
serializedInfoCache.put(stageId, bytes)
return bytes
}
}
}
def deserializeInfo(stageId: Int, bytes: Array[Byte]): (RDD[_], ShuffleDependency[_,_]) = {
synchronized {
val loader = Thread.currentThread.getContextClassLoader
val in = new GZIPInputStream(new ByteArrayInputStream(bytes))
val ser = SparkEnv.get.closureSerializer.newInstance
val objIn = ser.deserializeStream(in)
val rdd = objIn.readObject().asInstanceOf[RDD[_]]
val dep = objIn.readObject().asInstanceOf[ShuffleDependency[_,_]]
return (rdd, dep)
}
}
// Since both the JarSet and FileSet have the same format this is used for both.
def deserializeFileSet(bytes: Array[Byte]) : HashMap[String, Long] = {
val in = new GZIPInputStream(new ByteArrayInputStream(bytes))
val objIn = new ObjectInputStream(in)
val set = objIn.readObject().asInstanceOf[Array[(String, Long)]].toMap
return (HashMap(set.toSeq: _*))
}
def clearCache() {
synchronized {
serializedInfoCache.clear()
}
}
}
private[spark] class ShuffleMapTask(
stageId: Int,
var rdd: RDD[_],
var dep: ShuffleDependency[_,_],
var partition: Int,
@transient var locs: Seq[String])
extends Task[MapStatus](stageId)
with Externalizable
with Logging {
def this() = this(0, null, null, 0, null)
var split = if (rdd == null) {
null
} else {
rdd.splits(partition)
}
override def writeExternal(out: ObjectOutput) {
out.writeInt(stageId)
val bytes = ShuffleMapTask.serializeInfo(stageId, rdd, dep)
out.writeInt(bytes.length)
out.write(bytes)
out.writeInt(partition)
out.writeLong(generation)
out.writeObject(split)
}
override def readExternal(in: ObjectInput) {
val stageId = in.readInt()
val numBytes = in.readInt()
val bytes = new Array[Byte](numBytes)
in.readFully(bytes)
val (rdd_, dep_) = ShuffleMapTask.deserializeInfo(stageId, bytes)
rdd = rdd_
dep = dep_
partition = in.readInt()
generation = in.readLong()
split = in.readObject().asInstanceOf[Split]
}
override def run(attemptId: Long): MapStatus = {
val numOutputSplits = dep.partitioner.numPartitions
val partitioner = dep.partitioner
val taskContext = new TaskContext(stageId, partition, attemptId)
// Partition the map output.
val buckets = Array.fill(numOutputSplits)(new ArrayBuffer[(Any, Any)])
for (elem <- rdd.iterator(split, taskContext)) {
val pair = elem.asInstanceOf[(Any, Any)]
val bucketId = partitioner.getPartition(pair._1)
buckets(bucketId) += pair
}
val bucketIterators = buckets.map(_.iterator)
val compressedSizes = new Array[Byte](numOutputSplits)
val blockManager = SparkEnv.get.blockManager
for (i <- 0 until numOutputSplits) {
val blockId = "shuffle_" + dep.shuffleId + "_" + partition + "_" + i
// Get a Scala iterator from Java map
val iter: Iterator[(Any, Any)] = bucketIterators(i)
val size = blockManager.put(blockId, iter, StorageLevel.DISK_ONLY, false)
compressedSizes(i) = MapOutputTracker.compressSize(size)
}
// Execute the callbacks on task completion.
taskContext.executeOnCompleteCallbacks()
return new MapStatus(blockManager.blockManagerId, compressedSizes)
}
override def preferredLocations: Seq[String] = locs
override def toString = "ShuffleMapTask(%d, %d)".format(stageId, partition)
}
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