Hi, I tried to modify the code here to parse the nutch content data... http://svn.apache.org/viewvc/nutch/trunk/src/java/org/apache/nutch/parse/ParseSegment.java?view=markup And in the end of this email is a prototype that I have written to run map reduce to calculate the HTML content length of each URL that I have scraped.
The mapper part runs perfectly fine as expected, however, the whole program stops after all the mappers finished and the reducer did not get a chance to run: (I am sure there are certain number of pages got scraped and in the Eclipse console, there are same number of Mapper.. so I assume all the mapper finished.) Can anyone, who is pretty into writing java map reduce job take a look at my code and see what the error might be... I am not a Java developer at all so any debug trick or common sense will be appreciated! (I heard that it is fairly hard to debug code written using hadoop API... is that true?) Many thanks! /usr/bin _____________________________________________________ Eclipse Console Info Starting Mapper ... Key: http://url1 Result: 134943 Starting Mapper ... Key: http://url2 Result: 258588 Exception in thread "main" java.io.IOException: Job failed! at org.apache.hadoop.mapred.JobClient.runJob(JobClient.java:784) at arrow.ParseMapred.run(ParseMapred.java:68) at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:70) at arrow.ParseMapred.main(ParseMapred.java:18) _____________________________________________________ // my code package example; import ...; public class ParseMapred extends Configured implements Tool, Mapper<WritableComparable<?>, Content, Text, IntWritable>, Reducer<Text, IntWritable, Text, IntWritable> { public static void main(String[] args) throws Exception { int res = ToolRunner.run(NutchConfiguration.create(), new ParseMapred(), args); System.exit(res); } public void configure(JobConf job) { setConf(job); } public void close() throws IOException {} public void reduce(Text key, Iterator<IntWritable> values, OutputCollector<Text, IntWritable> output, Reporter reporter) throws IOException { System.out.println("Starting Reducer ..."); System.out.println("Reducer: " + "key" + key); output.collect(key, values.next()); // collect first value } public void map(WritableComparable<?> key, Content content, OutputCollector<Text, IntWritable> output, Reporter reporter) throws IOException { Text url = new Text(); IntWritable result = new IntWritable(); url.set("fail"); result = new IntWritable(1); try { System.out.println("Starting Mapper ..."); url.set(key.toString()); result = new IntWritable(content.getContent().length); System.out.println("Key: " + url); System.out.println("Result: " + result); output.collect(url, result); } catch (Exception e) { // TODO Auto-generated catch block output.collect(url, result); } } public int run(String[] args) throws Exception { JobConf job = new NutchJob(getConf()); job.setJobName("ParseData"); FileInputFormat.addInputPath(job, new Path("/Users/.../data/")); FileOutputFormat.setOutputPath(job, new Path("/Users/.../result")); job.setInputFormat(SequenceFileInputFormat.class); job.setOutputFormat(TextOutputFormat.class); job.setOutputKeyClass(Text.class); job.setOutputValueClass(IntWritable.class); job.setMapperClass(ParseMapred.class); job.setReducerClass(ParseMapred.class); JobClient.runJob(job); return 0; } }
