hadoop - mapreduce作业未执行

Question

我有一个简单的MapReduce作业，是从avro website借来的，做了一些小的修改(我删除了reducer)。基本上，它需要一个简单的avro文件作为输入。这是avro文件的架构

平均模式:

 {
"type": "record",
"name": "User",
"fields": [
{"name": "name", "type": "string"},
{"name": "favorite_number",  "type": "int"},
{"name":"favorite_color", "type": "string"}
]
}

这是我的mapreduce工作(映射器和主要功能):

public class ColorCountMapper extends Mapper<AvroKey<User>, NullWritable, Text, IntWritable> {

@Override
public void map(AvroKey<User> key, NullWritable value, Context context)  throws IOException, InterruptedException {

  CharSequence color = key.datum().getFavoriteColor();
  if (color == null) {
    color = "none";
  }
  context.write(new Text(color.toString()), new IntWritable(1));
}

}

和

public static void main(String[] args) throws Exception {


    Configuration conf = new Configuration();
    Job job = Job.getInstance(conf, "TestColor");
    job.setJarByClass(runClass.class);
    job.setJobName("Color Count");

    FileInputFormat.setInputPaths(job, new Path("in"));
    FileOutputFormat.setOutputPath(job, new Path("out"));

    job.setInputFormatClass(AvroKeyInputFormat.class);
    job.setMapperClass(ColorCountMapper.class);
    AvroJob.setInputKeySchema(job, User.getClassSchema());
    job.setMapOutputKeyClass(Text.class);
    job.setMapOutputValueClass(IntWritable.class);


    boolean r = job.waitForCompletion(true);
    System.out.println(r);  
}     

当我运行程序时，它返回false并且不会成功。我不知道问题所在。有人可以帮忙吗？

Answer 1

您已将“映射器”的值类型设置为 NullWritable 。然后在main / driver中，将Map-output值类设置为 IntWritable 。映射器中的值类型和主/驱动程序应相同。相应地修改程序。如果您有解决方案，请接受我的回答。