| /** |
| * 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.mapred; |
| |
| import java.io.IOException; |
| import java.util.concurrent.ConcurrentHashMap; |
| import java.util.concurrent.LinkedBlockingQueue; |
| import java.util.concurrent.atomic.AtomicInteger; |
| |
| import org.apache.commons.logging.Log; |
| import org.apache.commons.logging.LogFactory; |
| import org.apache.hadoop.fs.Path; |
| import org.apache.hadoop.mapreduce.server.tasktracker.TTConfig; |
| |
| class IndexCache { |
| |
| private final JobConf conf; |
| private final int totalMemoryAllowed; |
| private AtomicInteger totalMemoryUsed = new AtomicInteger(); |
| private static final Log LOG = LogFactory.getLog(IndexCache.class); |
| |
| private final ConcurrentHashMap<String,IndexInformation> cache = |
| new ConcurrentHashMap<String,IndexInformation>(); |
| |
| private final LinkedBlockingQueue<String> queue = |
| new LinkedBlockingQueue<String>(); |
| |
| public IndexCache(JobConf conf) { |
| this.conf = conf; |
| totalMemoryAllowed = |
| conf.getInt(TTConfig.TT_INDEX_CACHE, 10) * 1024 * 1024; |
| LOG.info("IndexCache created with max memory = " + totalMemoryAllowed); |
| } |
| |
| /** |
| * This method gets the index information for the given mapId and reduce. |
| * It reads the index file into cache if it is not already present. |
| * @param mapId |
| * @param reduce |
| * @param fileName The file to read the index information from if it is not |
| * already present in the cache |
| * @return The Index Information |
| * @throws IOException |
| */ |
| public IndexRecord getIndexInformation(String mapId, int reduce, |
| Path fileName) throws IOException { |
| |
| IndexInformation info = cache.get(mapId); |
| |
| if (info == null) { |
| info = readIndexFileToCache(fileName, mapId); |
| } else { |
| synchronized (info) { |
| while (null == info.mapSpillRecord) { |
| try { |
| info.wait(); |
| } catch (InterruptedException e) { |
| throw new IOException("Interrupted waiting for construction", e); |
| } |
| } |
| } |
| LOG.debug("IndexCache HIT: MapId " + mapId + " found"); |
| } |
| |
| if (info.mapSpillRecord.size() == 0 || |
| info.mapSpillRecord.size() < reduce) { |
| throw new IOException("Invalid request " + |
| " Map Id = " + mapId + " Reducer = " + reduce + |
| " Index Info Length = " + info.mapSpillRecord.size()); |
| } |
| return info.mapSpillRecord.getIndex(reduce); |
| } |
| |
| private IndexInformation readIndexFileToCache(Path indexFileName, |
| String mapId) throws IOException { |
| IndexInformation info; |
| IndexInformation newInd = new IndexInformation(); |
| if ((info = cache.putIfAbsent(mapId, newInd)) != null) { |
| synchronized (info) { |
| while (null == info.mapSpillRecord) { |
| try { |
| info.wait(); |
| } catch (InterruptedException e) { |
| throw new IOException("Interrupted waiting for construction", e); |
| } |
| } |
| } |
| LOG.debug("IndexCache HIT: MapId " + mapId + " found"); |
| return info; |
| } |
| LOG.debug("IndexCache MISS: MapId " + mapId + " not found") ; |
| SpillRecord tmp = null; |
| try { |
| tmp = new SpillRecord(indexFileName, conf); |
| } catch (Throwable e) { |
| tmp = new SpillRecord(0); |
| cache.remove(mapId); |
| throw new IOException("Error Reading IndexFile", e); |
| } finally { |
| synchronized (newInd) { |
| newInd.mapSpillRecord = tmp; |
| newInd.notifyAll(); |
| } |
| } |
| queue.add(mapId); |
| |
| if (totalMemoryUsed.addAndGet(newInd.getSize()) > totalMemoryAllowed) { |
| freeIndexInformation(); |
| } |
| return newInd; |
| } |
| |
| /** |
| * This method removes the map from the cache. It should be called when |
| * a map output on this tracker is discarded. |
| * @param mapId The taskID of this map. |
| */ |
| public void removeMap(String mapId) { |
| IndexInformation info = cache.remove(mapId); |
| if (info != null) { |
| totalMemoryUsed.addAndGet(-info.getSize()); |
| if (!queue.remove(mapId)) { |
| LOG.warn("Map ID" + mapId + " not found in queue!!"); |
| } |
| } else { |
| LOG.info("Map ID " + mapId + " not found in cache"); |
| } |
| } |
| |
| /** |
| * Bring memory usage below totalMemoryAllowed. |
| */ |
| private synchronized void freeIndexInformation() { |
| while (totalMemoryUsed.get() > totalMemoryAllowed) { |
| String s = queue.remove(); |
| IndexInformation info = cache.remove(s); |
| if (info != null) { |
| totalMemoryUsed.addAndGet(-info.getSize()); |
| } |
| } |
| } |
| |
| private static class IndexInformation { |
| SpillRecord mapSpillRecord; |
| |
| int getSize() { |
| return mapSpillRecord == null |
| ? 0 |
| : mapSpillRecord.size() * MapTask.MAP_OUTPUT_INDEX_RECORD_LENGTH; |
| } |
| } |
| } |