Java tutorial
/* * Cloud9: A Hadoop toolkit for working with big data * * Licensed 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. */ import java.util.Arrays; import org.apache.commons.cli.CommandLine; import org.apache.commons.cli.CommandLineParser; import org.apache.commons.cli.GnuParser; import org.apache.commons.cli.HelpFormatter; import org.apache.commons.cli.Option; import org.apache.commons.cli.OptionBuilder; import org.apache.commons.cli.Options; import org.apache.commons.cli.ParseException; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.conf.Configured; import org.apache.hadoop.fs.FileSystem; import org.apache.hadoop.fs.Path; import org.apache.hadoop.io.IntWritable; import org.apache.hadoop.mapreduce.Job; import org.apache.hadoop.mapreduce.lib.input.FileInputFormat; import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat; import org.apache.hadoop.mapreduce.lib.output.SequenceFileOutputFormat; import org.apache.hadoop.util.Tool; import org.apache.hadoop.util.ToolRunner; import org.apache.log4j.Logger; import edu.umd.cloud9.mapreduce.lib.input.NonSplitableSequenceFileInputFormat; import pagerank.PageRankNodeMultiSrc; /** * <p>Driver program for partitioning the graph.</p> * * @author Jimmy Lin * @author Michael Schatz */ public class PartitionGraph extends Configured implements Tool { private static final Logger LOG = Logger.getLogger(PartitionGraph.class); public static void main(String[] args) throws Exception { ToolRunner.run(new PartitionGraph(), args); } public PartitionGraph() { } private static final String INPUT = "input"; private static final String OUTPUT = "output"; private static final String NUM_NODES = "numNodes"; private static final String NUM_PARTITIONS = "numPartitions"; private static final String RANGE = "range"; /** * Runs this tool. */ @SuppressWarnings({ "static-access" }) public int run(String[] args) throws Exception { Options options = new Options(); options.addOption(new Option(RANGE, "use range partitioner")); options.addOption(OptionBuilder.withArgName("path").hasArg().withDescription("input path").create(INPUT)); options.addOption(OptionBuilder.withArgName("path").hasArg().withDescription("output path").create(OUTPUT)); options.addOption( OptionBuilder.withArgName("num").hasArg().withDescription("number of nodes").create(NUM_NODES)); options.addOption(OptionBuilder.withArgName("num").hasArg().withDescription("number of partitions") .create(NUM_PARTITIONS)); CommandLine cmdline; CommandLineParser parser = new GnuParser(); try { cmdline = parser.parse(options, args); } catch (ParseException exp) { System.err.println("Error parsing command line: " + exp.getMessage()); return -1; } if (!cmdline.hasOption(INPUT) || !cmdline.hasOption(OUTPUT) || !cmdline.hasOption(NUM_NODES) || !cmdline.hasOption(NUM_PARTITIONS)) { System.out.println("args: " + Arrays.toString(args)); HelpFormatter formatter = new HelpFormatter(); formatter.setWidth(120); formatter.printHelp(this.getClass().getName(), options); ToolRunner.printGenericCommandUsage(System.out); return -1; } String inPath = cmdline.getOptionValue(INPUT); String outPath = cmdline.getOptionValue(OUTPUT); int nodeCount = Integer.parseInt(cmdline.getOptionValue(NUM_NODES)); int numParts = Integer.parseInt(cmdline.getOptionValue(NUM_PARTITIONS)); boolean useRange = cmdline.hasOption(RANGE); LOG.info("Tool name: " + PartitionGraph.class.getSimpleName()); LOG.info(" - input dir: " + inPath); LOG.info(" - output dir: " + outPath); LOG.info(" - num partitions: " + numParts); LOG.info(" - node cnt: " + nodeCount); LOG.info(" - use range partitioner: " + useRange); Configuration conf = getConf(); conf.setInt("NodeCount", nodeCount); Job job = Job.getInstance(conf); job.setJobName(PartitionGraph.class.getSimpleName() + ":" + inPath); job.setJarByClass(PartitionGraph.class); job.setNumReduceTasks(numParts); FileInputFormat.setInputPaths(job, new Path(inPath)); FileOutputFormat.setOutputPath(job, new Path(outPath)); job.setInputFormatClass(NonSplitableSequenceFileInputFormat.class); job.setOutputFormatClass(SequenceFileOutputFormat.class); job.setMapOutputKeyClass(IntWritable.class); job.setMapOutputValueClass(PageRankNodeMultiSrc.class); job.setOutputKeyClass(IntWritable.class); job.setOutputValueClass(PageRankNodeMultiSrc.class); if (useRange) { job.setPartitionerClass(RangePartitioner.class); } FileSystem.get(conf).delete(new Path(outPath), true); job.waitForCompletion(true); return 0; } }