Java tutorial
/** * Copyright 2012 - CommonCrawl Foundation * * This program is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation, either version 3 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program. If not, see <http://www.gnu.org/licenses/>. * **/ package org.commoncrawl.mapred.ec2.postprocess.linkCollector; import java.io.IOException; import java.net.URI; import java.util.ArrayList; import java.util.Set; import java.util.SortedSet; import java.util.concurrent.LinkedBlockingQueue; import java.util.concurrent.Semaphore; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.fs.FileStatus; import org.apache.hadoop.fs.FileSystem; import org.apache.hadoop.fs.Path; import org.apache.hadoop.io.SequenceFile.CompressionType; import org.apache.hadoop.io.compress.SnappyCodec; import org.apache.hadoop.mapred.JobClient; import org.apache.hadoop.mapred.JobConf; import org.apache.hadoop.mapred.SequenceFileInputFormat; import org.apache.hadoop.mapred.SequenceFileOutputFormat; import org.commoncrawl.crawl.common.internal.CrawlEnvironment; import org.commoncrawl.mapred.ec2.postprocess.linkCollector.LinkKey.LinkKeyComparator; import org.commoncrawl.mapred.ec2.postprocess.linkCollector.LinkKey.LinkKeyPartitioner; import org.commoncrawl.util.CCStringUtils; import org.commoncrawl.util.JobBuilder; import org.commoncrawl.util.TextBytes; import com.google.common.collect.ImmutableSet; import com.google.common.collect.Sets; /** * * @author rana * */ public class LinkGraphDataEmitterJob { static final Log LOG = LogFactory.getLog(LinkGraphDataEmitterJob.class); static final Path internalEC2SegmentPath = new Path("crawl/ec2Import/segment"); static final Path internalMergedSegmentPath = new Path("crawl/ec2Import/mergedSegment"); static final String S3N_BUCKET_PREFIX = "s3n://aws-publicdatasets"; static final String SEGMENTS_PATH = "/common-crawl/parse-output/segment/"; static final String MERGE_INTERMEDIATE_OUTPUT_PATH = "/common-crawl/graph-output/intermediate/"; static final String VALID_SEGMENTS_PATH = "/common-crawl/parse-output/valid_segments/"; static final String JOB_SUCCESS_FILE = "_SUCCESS"; static final int MAX_SIMULTANEOUS_JOBS = 3; LinkedBlockingQueue<QueueItem> _queue = new LinkedBlockingQueue<QueueItem>(); Semaphore jobThreadSemaphore = new Semaphore(-(MAX_SIMULTANEOUS_JOBS - 1)); public static void processSegmentEC2(FileSystem s3fs, Configuration conf, long segmentId) throws IOException { Path outputPath = new Path(S3N_BUCKET_PREFIX + MERGE_INTERMEDIATE_OUTPUT_PATH + Long.toString(segmentId)); LOG.info("Starting Intermedaite Merge of Segment:" + segmentId + " Output path is:" + outputPath); if (s3fs.exists(outputPath)) { LOG.warn("Output Path Already Exists for Segment:" + segmentId + ".Deleting!"); s3fs.delete(outputPath, true); } // ok collect merge files ArrayList<Path> pathList = new ArrayList<Path>(); for (FileStatus metadataFile : s3fs.globStatus(new Path(SEGMENTS_PATH, segmentId + "/metadata-*"))) { pathList.add(metadataFile.getPath().makeQualified(s3fs)); } LOG.info("Input Paths for Segment:" + segmentId + " are:" + pathList); JobConf jobConf = new JobBuilder("Intermediate merge for:" + segmentId, conf).inputs(pathList) .inputFormat(SequenceFileInputFormat.class).keyValue(TextBytes.class, TextBytes.class) .mapper(LinkGraphDataEmitter.class).maxMapAttempts(7).maxReduceAttempts(7).maxMapTaskFailures(1000) .reuseJVM(1000).reducer(LinkGraphDataEmitter.class, false).numReducers(500) .speculativeExecution(true).output(outputPath).outputFormat(SequenceFileOutputFormat.class) .compressMapOutput(true).compressor(CompressionType.BLOCK, SnappyCodec.class).build(); JobClient.runJob(jobConf); } public static void mergeSegmentInternal(FileSystem fs, Configuration conf, long segmentId, Path affinityPath) throws IOException { Path outputPath = JobBuilder.tempDir(conf, Long.toString(segmentId)); LOG.info("Starting Intermedaite Merge of Segment:" + segmentId + " Temp Output path is:" + outputPath); fs.delete(outputPath, true); Path inputPath = new Path(internalEC2SegmentPath, Long.toString(segmentId)); LOG.info("Input Path for Segment:" + segmentId + " is:" + inputPath); JobConf jobConf = new JobBuilder("Intermediate merge for:" + segmentId, conf).input(inputPath) .inputFormat(SequenceFileInputFormat.class).keyValue(TextBytes.class, TextBytes.class) .mapper(LinkDataResharder.class).maxMapTaskFailures(100).reducer(LinkDataResharder.class, true) .partition(LinkKeyPartitioner.class).sort(LinkKeyComparator.class) .numReducers(CrawlEnvironment.NUM_DB_SHARDS) .setAffinity(affinityPath, ImmutableSet.of("ccd001.commoncrawl.org")).speculativeMapExecution() .output(outputPath).outputFormat(SequenceFileOutputFormat.class) .compressMapOutput(true).compressor(CompressionType.BLOCK, SnappyCodec.class) .build(); JobClient.runJob(jobConf); Path finalOutputPath = new Path(internalMergedSegmentPath, Long.toString(segmentId)); LOG.info("Renaming tempoutput:" + outputPath + " to:" + finalOutputPath); fs.rename(outputPath, finalOutputPath); } private static SortedSet<Long> scanForValidSegments(FileSystem fs) throws IOException { SortedSet<Long> completeSegmentIds = Sets.newTreeSet(); for (FileStatus fileStatus : fs.globStatus(new Path(VALID_SEGMENTS_PATH + "[0-9]*"))) { completeSegmentIds.add(Long.parseLong(fileStatus.getPath().getName())); } return completeSegmentIds; } private static SortedSet<Long> scanForMergedSegments(FileSystem fs) throws IOException { SortedSet<Long> completeSegmentIds = Sets.newTreeSet(); for (FileStatus fileStatus : fs.globStatus(new Path(MERGE_INTERMEDIATE_OUTPUT_PATH + "[0-9]*"))) { // ok look for the SUCCESS file Path successPath = new Path(fileStatus.getPath(), JOB_SUCCESS_FILE); if (fs.exists(successPath)) { completeSegmentIds.add(Long.parseLong(fileStatus.getPath().getName())); } } return completeSegmentIds; } public LinkGraphDataEmitterJob(Configuration conf) throws Exception { FileSystem fs = FileSystem.get(new URI("s3n://aws-publicdatasets"), conf); LOG.info("FileSystem is:" + fs.getUri() + " Scanning for valid segments"); SortedSet<Long> validSegments = scanForValidSegments(fs); LOG.info("There are: " + validSegments.size() + " valid segments. Scanning for Merged Segments"); SortedSet<Long> mergedSegments = scanForMergedSegments(fs); LOG.info("There are: " + mergedSegments.size() + " merged Segments"); // calculate difference Set<Long> segmentsToProcess = Sets.difference(validSegments, mergedSegments); LOG.info("There are: " + segmentsToProcess.size() + " Segments that need to be merged"); // ok we are ready to go .. int iteration = 0; for (long segmentId : segmentsToProcess) { LOG.info("Queueing Segment:" + segmentId + " for Merge"); queue(fs, conf, segmentId); } // queue shutdown items for (int i = 0; i < MAX_SIMULTANEOUS_JOBS; ++i) { _queue.put(new QueueItem()); } } void run() { LOG.info("Starting Threads"); // startup threads .. for (int i = 0; i < MAX_SIMULTANEOUS_JOBS; ++i) { Thread thread = new Thread(new QueueTask()); thread.start(); } // ok wait for them to die LOG.info("Waiting for Queue Threads to Die"); jobThreadSemaphore.acquireUninterruptibly(); LOG.info("Queue Threads Dead. Exiting"); } public static void main(String[] args) throws Exception { if (args.length != 0 && args[0].equalsIgnoreCase("--runOnEC2")) { Configuration conf = new Configuration(); conf.addResource(new Path("/home/hadoop/conf/core-site.xml")); conf.addResource(new Path("/home/hadoop/conf/mapred-site.xml")); LinkGraphDataEmitterJob task = new LinkGraphDataEmitterJob(conf); task.run(); } else { Configuration conf = new Configuration(); FileSystem fs = FileSystem.get(conf); FileStatus segments[] = fs.globStatus(new Path(internalEC2SegmentPath, "[0-9]*")); // first find an affinity segment Path affinityTarget = null; for (FileStatus segment : segments) { long segmentId = Long.parseLong(segment.getPath().getName()); Path stage1Path = new Path(internalMergedSegmentPath, Long.toString(segmentId)); if (fs.exists(stage1Path)) { LOG.info("Found existing segment to build affinity against"); affinityTarget = stage1Path; } } for (FileStatus segment : segments) { long segmentId = Long.parseLong(segment.getPath().getName()); LOG.info("Segment Id:" + segmentId); Path stage1Path = new Path(internalMergedSegmentPath, Long.toString(segmentId)); if (!fs.exists(stage1Path)) { LOG.info("Need to run stage 1 for Segment:" + segmentId); try { mergeSegmentInternal(fs, conf, segmentId, affinityTarget); if (affinityTarget == null) { LOG.info("Adopting Successfully create merge output as affinity segment"); affinityTarget = stage1Path; } } catch (IOException e) { LOG.error("stage 1 for Segment:" + segmentId + " Failed with Exception:" + CCStringUtils.stringifyException(e)); } } } } } static class QueueItem { QueueItem() { segmentId = -1L; } QueueItem(FileSystem fs, Configuration conf, long segmentId) { this.conf = conf; this.fs = fs; this.segmentId = segmentId; } public Configuration conf; public FileSystem fs; public long segmentId; } class QueueTask implements Runnable { @Override public void run() { while (true) { LOG.info("Queue Thread:" + Thread.currentThread().getId() + " Running"); try { QueueItem item = _queue.take(); if (item.segmentId != -1L) { LOG.info("Queue Thread:" + Thread.currentThread().getId() + " got segment:" + item.segmentId); LOG.info("Queue Thread:" + Thread.currentThread().getId() + " Starting Job"); try { processSegmentEC2(item.fs, item.conf, item.segmentId); } catch (IOException e) { LOG.error("Queue Thread:" + Thread.currentThread().getId() + " threw exception:" + CCStringUtils.stringifyException(e)); } } else { LOG.info("Queue Thread:" + Thread.currentThread().getId() + " Got Shutdown Queue Item - EXITING"); break; } } catch (InterruptedException e) { } } LOG.info("Queue Thread:" + Thread.currentThread().getId() + " Released Semaphore"); jobThreadSemaphore.release(); } } private void queue(FileSystem fs, Configuration conf, long segmentId) { try { _queue.put(new QueueItem(fs, conf, segmentId)); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } } }