Github user rxin commented on a diff in the pull request: https://github.com/apache/spark/pull/2931#discussion_r19454541 --- Diff: streaming/src/test/scala/org/apache/spark/streaming/rdd/HDFSBackedBlockRDDSuite.scala --- @@ -0,0 +1,163 @@ +/* + * 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.streaming.rdd + +import java.io.File +import java.util.concurrent.atomic.AtomicInteger + +import org.apache.spark.{SparkConf, SparkContext} + +import scala.collection.mutable.ArrayBuffer +import org.scalatest.{BeforeAndAfterAll, BeforeAndAfter, FunSuite} + +import com.google.common.io.Files +import org.apache.hadoop.conf.Configuration + +import org.apache.spark.storage.{BlockManager, BlockId, StorageLevel, StreamBlockId} +import org.apache.spark.streaming.util.{WriteAheadLogFileSegment, WriteAheadLogWriter} + +class HDFSBackedBlockRDDSuite extends FunSuite with BeforeAndAfter with BeforeAndAfterAll { + val conf = new SparkConf() + .setMaster("local[2]") + .setAppName(this.getClass.getSimpleName) + val hadoopConf = new Configuration() + // Since the same BM is reused in all tests, use an atomic int to generate ids + val idGenerator = new AtomicInteger(0) + + var sparkContext: SparkContext = null + var blockManager: BlockManager = null + var file: File = null + var dir: File = null + + before { + blockManager = sparkContext.env.blockManager + dir = Files.createTempDir() + file = new File(dir, "BlockManagerWrite") + } + + after { + file.delete() + dir.delete() + } + + override def beforeAll(): Unit = { + sparkContext = new SparkContext(conf) + } + + override def afterAll(): Unit = { + // Copied from LocalSparkContext which can't be imported since spark-core test-jar does not + // get imported properly by sbt even if it is created. + sparkContext.stop() + System.clearProperty("spark.driver.port") + } + + test("Data available in BM and HDFS") { + testHDFSBackedRDD(5, 5, 20, 5) + } + + test("Data available in in BM but not in HDFS") { + testHDFSBackedRDD(5, 0, 20, 5) + } + + test("Data available in in HDFS and not in BM") { + testHDFSBackedRDD(0, 5, 20, 5) + } + + test("Data partially available in BM, and the rest in HDFS") { + testHDFSBackedRDD(3, 2, 20, 5) + } + + /** + * Write a bunch of events into the HDFS Block RDD. Put a part of all of them to the + * BlockManager, so all reads need not happen from HDFS. + * @param total Total number of Strings to write + * @param blockCount Number of blocks to write (therefore, total # of events per block = + * total/blockCount + */ + private def testHDFSBackedRDD( + writeToBMCount: Int, + writeToHDFSCount: Int, + total: Int, + blockCount: Int + ) { + val countPerBlock = total / blockCount + val blockIds = (0 until blockCount).map { i => + StreamBlockId(idGenerator.incrementAndGet(), idGenerator.incrementAndGet()) + } + + val writtenStrings = generateData(total, countPerBlock) + + if (writeToBMCount != 0) { + (0 until writeToBMCount).foreach { i => + blockManager + .putIterator(blockIds(i), writtenStrings(i).iterator, StorageLevel.MEMORY_ONLY_SER) + } + } + + val segments = { + if (writeToHDFSCount != 0) { + // Generate some fake segments for the blocks in BM so the RDD does not complain + generateFakeSegments(writeToBMCount) ++ + writeDataToHDFS(writtenStrings.slice(writeToBMCount, blockCount), + blockIds.slice(writeToBMCount, blockCount)) + } else { + generateFakeSegments(blockCount) + } + } + + val rdd = new HDFSBackedBlockRDD[String](sparkContext, hadoopConf, blockIds.toArray, + segments.toArray, false, StorageLevel.MEMORY_ONLY) + + val dataFromRDD = rdd.collect() + // verify each partition is equal to the data pulled out + assert(writtenStrings.flatten === dataFromRDD) + } + + /** + * Write data to HDFS and get a list of Seq of Seqs in which each Seq represents the data that + * went into one block. + * @param count Number of Strings to write + * @param countPerBlock Number of Strings per block + * @return Seq of Seqs, each of these Seqs is one block + */ + private def generateData( + count: Int, + countPerBlock: Int + ): Seq[Seq[String]] = { + val strings = (0 until count).map { _ => scala.util.Random.nextString(50)} + strings.grouped(countPerBlock).toSeq + } + + private def writeDataToHDFS( + blockData: Seq[Seq[String]], + blockIds: Seq[BlockId] + ): Seq[WriteAheadLogFileSegment] = { + assert(blockData.size === blockIds.size) + val segments = new ArrayBuffer[WriteAheadLogFileSegment]() + val writer = new WriteAheadLogWriter(file.toString, hadoopConf) + blockData.zip(blockIds).foreach { + case (data, id) => + segments += writer.write(blockManager.dataSerialize(id, data.iterator)) + } + writer.close() + segments + } + + private def generateFakeSegments(count: Int): Seq[WriteAheadLogFileSegment] = { + (0 until count).map { _ => new WriteAheadLogFileSegment("random", 0l, 0) } --- End diff -- Seq.fill
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