Question

我想在hadoop-1.0.1上运行一个应用程序，我注意到应用程序没有进入map函数。在hadoop local上，应用程序正常运行，但在分布式hadoop上，不会调用map函数。

我有这个结构

Class Embed {

public static class Map extends MapReduceBase implements Mapper<LongWritable, Text, Text, LongWritable> {
     public void map(LongWritable key, Text value, OutputCollector<Text, LongWritable> output, Reporter reporter) throws IOException {
          ........
     }
}

public static class Reduce extends MapReduceBase implements Reducer<Text, LongWritable, Text, LongWritable> {
        public void reduce(Text key, Iterator<LongWritable> values, OutputCollector<Text, LongWritable> output, Reporter reporter) throws IOException {
               ..........
        }
public static void main(String[] args) throws Exception {
        readArguments(args);
    JobConf conf = new JobConf(Embed.class);
    conf.setJobName("embed");

    conf.setOutputKeyClass(Text.class);
    conf.setOutputValueClass(LongWritable.class);

    conf.setMapperClass(Map.class);
    //conf.setCombinerClass(Reduce.class);
    conf.setReducerClass(Reduce.class);

    conf.setInputFormat(TextInputFormat.class);
    conf.setOutputFormat(TextOutputFormat.class);

    FileInputFormat.setInputPaths(conf, new Path(input));
    FileOutputFormat.setOutputPath(conf, new Path(output));

    JobClient.runJob(conf);

}
}

感谢您的帮助。

Answer 1

检查输入路径是否对服务器有效。如果那里没有数据，则不会调用映射器，因为每个记录调用一次。

在hadoop上没有调用map函数

1 个答案: