gpt4 book ai didi

hadoop - MapReduce 旧 API - 将命令行参数传递给 map

转载 作者:可可西里 更新时间:2023-11-01 16:59:37 25 4
gpt4 key购买 nike

我正在编写一个 MapReduce 作业,用于使用旧 API 在存储在 HDFS 中的输入文件中查找搜索字符串(通过命令行参数传递)的出现。

下面是我的驱动类 -

public class StringSearchDriver
{

public static void main(String[] args) throws IOException
{
JobConf jc = new JobConf(StringSearchDriver.class);
jc.set("SearchWord", args[2]);
jc.setJobName("String Search");
FileInputFormat.addInputPath(jc, new Path(args[0]));
FileOutputFormat.setOutputPath(jc, new Path(args[1]));
jc.setMapperClass(StringSearchMap.class);
jc.setReducerClass(StringSearchReduce.class);
jc.setOutputKeyClass(Text.class);
jc.setOutputValueClass(IntWritable.class);
JobClient.runJob(jc);
}
}

下面是我的 Mapper 类 -

public class StringSearchMap extends MapReduceBase implements
Mapper<LongWritable, Text, Text, IntWritable>
{
String searchWord;

public void configure(JobConf jc)
{
searchWord = jc.get("SearchWord");

}



@Override
public void map(LongWritable key, Text value,
OutputCollector<Text, IntWritable> out, Reporter reporter)
throws IOException
{
String[] input = value.toString().split("");

for(String word:input)
{
if (word.equalsIgnoreCase(searchWord))
out.collect(new Text(word), new IntWritable(1));
}
}

}

在运行作业时(传递的命令行字符串是“hi”),出现以下错误 -

14/09/21 22:35:41 INFO mapred.JobClient: Task Id : attempt_201409212134_0005_m_000001_2, Status : FAILED
java.lang.ClassCastException: interface javax.xml.soap.Text
at java.lang.Class.asSubclass(Class.java:3129)
at org.apache.hadoop.mapred.JobConf.getOutputKeyComparator(JobConf.java:795)
at org.apache.hadoop.mapred.MapTask$MapOutputBuffer.<init>(MapTask.java:964)
at org.apache.hadoop.mapred.MapTask.runOldMapper(MapTask.java:422)
at org.apache.hadoop.mapred.MapTask.run(MapTask.java:366)
at org.apache.hadoop.mapred.Child$4.run(Child.java:255)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:416)
at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1190)
at org.apache.hadoop.mapred.Child.main(Child.java:249)

请提出建议。

最佳答案

您自动导入了错误的导入。而不是 import org.apache.hadoop.io.Textimport javax.xml.soap.Text

您可以在此 blog 中找到示例错误导入.

一点,最好采用New API

编辑

我使用了新的 API

import java.io.IOException;
import java.util.StringTokenizer;

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;

/**
* @author Unmesha sreeveni
* @Date 23 sep 2014
*/
public class StringSearchDriver extends Configured implements Tool {
public static class Map extends
Mapper<LongWritable, Text, Text, IntWritable> {

private final static IntWritable one = new IntWritable(1);
private Text word = new Text();

public void map(LongWritable key, Text value, Context context)
throws IOException, InterruptedException {
Configuration conf = context.getConfiguration();
String line = value.toString();
String searchString = conf.get("word");
StringTokenizer tokenizer = new StringTokenizer(line);
while (tokenizer.hasMoreTokens()) {
String token = tokenizer.nextToken();
if(token.equals(searchString)){
word.set(token);
context.write(word, one);
}

}
}
}

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

public void reduce(Text key, Iterable<IntWritable> values,
Context context) throws IOException, InterruptedException {

int sum = 0;
for (IntWritable val : values) {
sum += val.get();
}
context.write(key, new IntWritable(sum));
}
}
public static void main(String[] args) throws Exception {
Configuration conf = new Configuration();
int res = ToolRunner.run(conf, new StringSearchDriver(), args);
System.exit(res);

}
@Override
public int run(String[] args) throws Exception {
// TODO Auto-generated method stub
if (args.length != 3) {
System.out
.printf("Usage: Search String <input dir> <output dir> <search word> \n");
System.exit(-1);
}

String source = args[0];
String dest = args[1];
String searchword = args[2];
Configuration conf = new Configuration();
conf.set("word", searchword);
Job job = new Job(conf, "Search String");
job.setJarByClass(StringSearchDriver.class);
FileSystem fs = FileSystem.get(conf);

Path in =new Path(source);
Path out =new Path(dest);
if (fs.exists(out)) {
fs.delete(out, true);
}

job.setMapOutputKeyClass(Text.class);
job.setMapOutputValueClass(IntWritable.class);
job.setOutputKeyClass(Text.class);
job.setOutputValueClass(IntWritable.class);
job.setMapperClass(Map.class);
job.setReducerClass(Reduce.class);
job.setInputFormatClass(TextInputFormat.class);
job.setOutputFormatClass(TextOutputFormat.class);
FileInputFormat.addInputPath(job, in);
FileOutputFormat.setOutputPath(job, out);
boolean sucess = job.waitForCompletion(true);
return (sucess ? 0 : 1);
}
}

这有效。

关于hadoop - MapReduce 旧 API - 将命令行参数传递给 map ,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/25962454/

25 4 0
Copyright 2021 - 2024 cfsdn All Rights Reserved 蜀ICP备2022000587号
广告合作:1813099741@qq.com 6ren.com