hadoop mapreduce查看System.out的数据

本文介绍如何通过Hadoop作业追踪页面访问MapReduce任务的日志。具体步骤包括:打开http://localhost:50030/jobtracker.jsp,选择已完成的任务,点击Map或Reduce阶段,再点击对应任务编号,最后查看stdout日志。

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Actually stdout only shows the System.out.println() of the non map reduce classes. The System.out.println() for map and reduce phases can be seen in the logs. Easy way to access the logs is http://localhost:50030/jobtracker.jsp- >click on the completed job->click on map or reduce task->click on tasknumber->task logs->stdout logs.

package com.dajiangtai.hadoop.tv; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.conf.Configured; import org.apache.hadoop.fs.Path; import org.apache.hadoop.io.LongWritable; import org.apache.hadoop.io.Text; import org.apache.hadoop.mapreduce.Job; import org.apache.hadoop.mapreduce.Mapper; import org.apache.hadoop.mapreduce.lib.input.FileInputFormat; import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat; import org.apache.hadoop.util.GenericOptionsParser; import org.apache.hadoop.util.Tool; import org.apache.hadoop.util.ToolRunner; public class ParseAndFilterLog extends Configured implements Tool { public static class ExtractTVMsgLogMapper extends Mapper<LongWritable, Text, Text, Text, Text> { public void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException { DataUtil.transData(value.toString(), context); } } public int run(String[] args) throws Exception { Configuration conf = new Configuration(); String[] otherArgs = new GenericOptionsParser(conf, args).getRemainingArgs(); if (otherArgs.length < 2) { System.err.println("Usage: ParseAndFilterLog <in> <out>"); System.exit(2); } Job job = Job.getInstance(conf, "ParseAndFilterLog"); job.setJarByClass(ParseAndFilterLog.class); job.setMapperClass(ExtractTVMsgLogMapper.class); job.setOutputKeyClass(Text.class); job.setOutputValueClass(Text.class); FileInputFormat.addInputPath(job, new Path(otherArgs[0])); FileOutputFormat.setOutputPath(job, new Path(otherArgs[1])); job.getConfiguration().set("mapreduce.output.textoutputformat.separator", "@"); return job.waitForCompletion(true) ? 0 : 1; } public static void main(String[] args) throws Exception { int exitCode = ToolRunner.run(new Configuration(), new ParseAndFilterLog(), args); System.exit(exitCode); } }修改这段代码使其不报错
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