FMX commented on code in PR #1830: URL: https://github.com/apache/incubator-celeborn/pull/1830#discussion_r1318000082
########## client-mr/mr/src/main/java/org/apache/hadoop/mapreduce/task/reduce/CelebornShuffleFetcher.java: ########## @@ -0,0 +1,224 @@ +/* + * 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.hadoop.mapreduce.task.reduce; + +import java.io.IOException; +import java.lang.reflect.Field; + +import org.apache.hadoop.io.compress.CodecPool; +import org.apache.hadoop.io.compress.Decompressor; +import org.apache.hadoop.mapred.Counters; +import org.apache.hadoop.mapred.Reporter; +import org.apache.hadoop.mapred.TaskStatus; +import org.apache.hadoop.mapreduce.TaskAttemptID; +import org.apache.hadoop.mapreduce.TaskID; +import org.apache.hadoop.mapreduce.TaskType; +import org.apache.hadoop.util.Progress; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import org.apache.celeborn.client.read.CelebornInputStream; +import org.apache.celeborn.common.exception.CelebornIOException; +import org.apache.celeborn.common.unsafe.Platform; + +public class CelebornShuffleFetcher<K, V> { + private static final Logger logger = LoggerFactory.getLogger(CelebornShuffleFetcher.class); + private final TaskAttemptID reduceId; + private final Reporter reporter; + private final TaskStatus status; + private final MergeManager<K, V> merger; + private final Progress progress; + private final ShuffleClientMetrics metrics; + private final CelebornInputStream celebornInputStream; + private volatile boolean stopped = false; + private int uniqueMapId = 0; + private final Counters.Counter ioErrs; + private boolean hasPendingData = false; + private long inputShuffleSize; + private byte[] shuffleData; + + public CelebornShuffleFetcher( + TaskAttemptID reduceId, + TaskStatus status, + MergeManager<K, V> merger, + Progress progress, + Reporter reporter, + ShuffleClientMetrics metrics, + CelebornInputStream input) { + this.reduceId = reduceId; + this.reporter = reporter; + this.status = status; + this.merger = merger; + this.progress = progress; + this.metrics = metrics; + this.celebornInputStream = input; + + ioErrs = reporter.getCounter("Shuffle Errors", "IO_ERROR"); + } + + // fetch all push data and merge + public void fetchAndMerge() { + while (!stopped) { + try { + // If merge is on, block + merger.waitForResource(); + // Do shuffle + metrics.threadBusy(); + // read blocks + fetchToLocalAndMerge(); + } catch (Exception e) { + logger.error("Celeborn shuffle fetcher fetch data failed.", e); + } finally { + metrics.threadFree(); + } + } + } + + private byte[] getShuffleBlock() throws IOException { + // get len + byte[] header = new byte[4]; + int count = celebornInputStream.read(header); + if (count == -1) { + stopped = true; + return null; + } + while (count != header.length) { + count += celebornInputStream.read(header, count, 4 - count); + } + + // get data + int blockLen = Platform.getInt(header, Platform.BYTE_ARRAY_OFFSET); + inputShuffleSize += blockLen; + byte[] shuffleData = new byte[blockLen]; + count = 0; + count = celebornInputStream.read(shuffleData); + while (count != shuffleData.length) { + count += celebornInputStream.read(shuffleData, count, blockLen - count); + if (count == -1) { + // read shuffle is done. + stopped = true; + throw new CelebornIOException("Read mr shuffle failed."); + } + } + return shuffleData; + } + + private void fetchToLocalAndMerge() throws IOException { + if (!hasPendingData) { + shuffleData = getShuffleBlock(); + } + + if (shuffleData != null) { + // start to merge + if (wrapMapOutput(shuffleData)) { + hasPendingData = false; + } else { + return; + } + + updateStatus(); + reporter.progress(); + } else { + celebornInputStream.close(); + metrics.inputBytes(inputShuffleSize); + logger.info("reduce task {} read {} bytes", reduceId, inputShuffleSize); + stopped = true; + } + } + + private boolean wrapMapOutput(byte[] shuffleData) throws IOException { + // treat push data as mapoutput + TaskAttemptID mapId = + new TaskAttemptID(new TaskID(reduceId.getJobID(), TaskType.MAP, uniqueMapId++), 0); + MapOutput<K, V> mapOutput = null; + try { + mapOutput = merger.reserve(mapId, shuffleData.length, 0); + } catch (IOException ioe) { + ioErrs.increment(1); + throw ioe; + } + if (mapOutput == null) { + logger.info( + "Celeborn fetcher returned status wait because reserve buffer for shuffle get null"); + hasPendingData = true; + return false; + } + + // write data to mapOutput + try { + writeShuffle(mapOutput, shuffleData); + // let the merger knows this block is ready for merging + mapOutput.commit(); + } catch (Throwable t) { + ioErrs.increment(1); + mapOutput.abort(); + throw new CelebornIOException( + "Reduce: {} " + + reduceId + + " fetch failed to {} " + + mapOutput.getClass().getSimpleName() + + " due to: {} " + + t.getClass().getName()); + } + return true; + } + + private Decompressor getDecompressor(InMemoryMapOutput inMemoryMapOutput) + throws CelebornIOException { + try { + Class clazz = Class.forName(InMemoryMapOutput.class.getName()); + Field deCompressorField = clazz.getDeclaredField("decompressor"); + deCompressorField.setAccessible(true); + return (Decompressor) deCompressorField.get(inMemoryMapOutput); + } catch (Exception e) { + throw new CelebornIOException("Get Decompressor fail " + e.getMessage()); + } + } + + private void writeShuffle(MapOutput mapOutput, byte[] shuffle) throws CelebornIOException { + if (mapOutput instanceof InMemoryMapOutput) { + InMemoryMapOutput inMemoryMapOutput = (InMemoryMapOutput) mapOutput; + CodecPool.returnDecompressor(getDecompressor(inMemoryMapOutput)); + byte[] memory = inMemoryMapOutput.getMemory(); + System.arraycopy(shuffle, 0, memory, 0, shuffle.length); + } else if (mapOutput instanceof OnDiskMapOutput) { Review Comment: Reduce will spill shuffle to local disks and do out-of-memory merge sort. -- This is an automated message from the Apache Git Service. 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