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Windows远程调试Hadoop

Posted on 2014-06-03 21:09 tangtb 阅读(1728) 评论(0)  编辑  收藏 所属分类: Hadoop

前置条件

成功安装配置Hadoop集群

成功编译安装Hadoop Eclipse插件

本地有和服务器相同版本的Hadoop安装包,并已解压(本例使用hadoop-1.1.2

启动Hadoop集群

配置hadoop installation directory

Eclipse选择WindowàPreferens,弹出Preferens窗口,选择左侧Hadoop Map/Reduce选项,右侧配置Hadoop installation directory

配置Map/Reduce Locations

Eclipse选择WindowàOpen PerspectiveàMap/Reduce,打开Map/Reduce视图。

点击上图右上角蓝色小象,弹出Hadoop Location新增配置窗口,如下图:

Location name:自定义Location名称

Map/Reduce Mastermapred-site.xmlmapred.job.tracker属性值

DFS Mastercore-site.xmlfs.default.name属性值

User name:服务器端连接hdfs的用户名

连接成功,如上图左侧所示,列出了当前HDFS中的目录。

新建MapReduce Project

NCDC求年最高气温为例,将气温数据放在/user/hadoop/ncdc/input目录下,如图所示:

创建测试类MaxTempTest代码如下:

package com.hadoop.test;

 

import java.io.IOException;

 

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.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.Reducer;

import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;

import org.apache.hadoop.mapreduce.lib.input.TextInputFormat;

import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;

import org.apache.hadoop.mapreduce.lib.output.TextOutputFormat;

import org.apache.hadoop.util.Tool;

import org.apache.hadoop.util.ToolRunner;

 

public class MaxTempTest extends Configured implements Tool {

   

    public static class MaxTempMapper extends Mapper<LongWritable, Text, Text, IntWritable> {

      

       private static final int MISSING = 9999;

 

       protected void map(LongWritable key, Text value, Context context)

              throws IOException, InterruptedException {

           //从输入文本中解析出年和气温

           String line = value.toString();

           String year = line.substring(15, 19);

           int airTemp = 0;

           if (line.length() > 87) {

              if (line.charAt(87) == '+') {

                  airTemp = Integer.parseInt(line.substring(88, 92));

              } else {

                  airTemp = Integer.parseInt(line.substring(87, 92));

              }

              String quality = line.substring(92, 93);

              if (airTemp != MISSING && quality.matches("[01459]")) {

                  context.write(new Text(year), new IntWritable(airTemp));

              }

           } else {

              System.out.println("year: " + year + ", " + context.getInputSplit().toString());

              context.write(new Text(year), new IntWritable(airTemp));

           }

       }

    }

   

    public static class MaxTempReducer extends Reducer<Text, IntWritable, Text, IntWritable> {

      

       protected void reduce(Text key, java.lang.Iterable<IntWritable> values, Context context) throws IOException ,InterruptedException {

           //计算最大值

           int maxValue = Integer.MIN_VALUE;

           for (IntWritable value : values) {

              maxValue = Math.max(maxValue, value.get());

           }

           context.write(key, new IntWritable(maxValue));

       }

    }

   

    /**

     * @param args

     */

    public static void main(String[] args) {

       // TODO Auto-generated method stub

       try {

           int exitCode = ToolRunner.run(new MaxTempTest(), args);

           System.exit(exitCode);

       } catch (Exception e) {

           // TODO Auto-generated catch block

           e.printStackTrace();

       }

    }

   

    @Override

    public int run(String[] args) throws Exception {

       // TODO Auto-generated method stub

      

       if (args.length != 2) {

           System.out.println("Usage: MaxTempTest <input path> <output path>");

           System.exit(-1);

       }

      

       Configuration config = new Configuration();

       try {

           FileSystem hdfs = FileSystem.get(config);

           Job job = new Job(config, "Max TempTest");

           //设置输出KeyValue的类型

           job.setOutputKeyClass(Text.class);

           job.setOutputValueClass(IntWritable.class);     

          

           job.setJarByClass(MaxTempTest.class);

           job.setMapperClass(MaxTempMapper.class); //设置Mapper

           job.setReducerClass(MaxTempReducer.class);    //设置Reducer

           //设置输入输出格式

           job.setInputFormatClass(TextInputFormat.class);

           job.setOutputFormatClass(TextOutputFormat.class);

          

           Path inputDir = new Path(args[0]);

           Path outputDir = new Path(args[1]);

           //如果输出目录已经存在,删除该目录

           if (hdfs.exists(outputDir)) {

              hdfs.delete(outputDir, true);

           }

           //设置输入输出路径

           FileInputFormat.setInputPaths(job, inputDir);

           FileOutputFormat.setOutputPath(job, outputDir);

           //提交作业

           job.waitForCompletion(true);

       } catch (IOException e) {

           e.printStackTrace();

       } catch (ClassNotFoundException e) {

           // TODO Auto-generated catch block

           e.printStackTrace();

       } catch (InterruptedException e) {

           // TODO Auto-generated catch block

           e.printStackTrace();

       }

       return 0;

    }

}

运行测试项目

在测试类MaxTempTest右键àRun AsàRun Configurations弹出Run Configurations窗口,右键Java ApplicationàNew,新建名为MaxTempTest,如下图所示:

点右侧Arguments配置运行参数,在Program arguments中输入:

hdfs://10.120.10.11:9090/user/hadoop/ncdc/input hdfs://10.120.10.11:9090/user/hadoop/ncdc/output

在测试类MaxTempTest右键àRun AsàRun on Hadoop弹出Select Hadoop location窗口,如下图所示:

选择“Choose an existing server from the list below”,点击“Finish”,提交作业。

运行错误一

解决方法:

hadoop-1.1.2\src\core\org\apache\hadoop\fs目录找到FileUtil.java,将该文件复制到自己的测试项目中,包名与FileUtil中的package定义相同,注释掉类中checkReturnValue方法中的代码,如下图所示:

运行错误二

解决方法:

在服务器端修改目录权限,执行hadoop fs -chmod -R 777 ./ncdc命令

运行结果

如上图所示,作业运行成功。Eclipse左侧“DFS Locations”右键刷新”ncdc”目录,双击打开part-r-00000查看运行结果,如下图所示:

 

 

 


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