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私は巨大なノーを持っています。小さなファイルの場合、CombineFileInputFormat を使用してファイルをマージし、MR ジョブで各ファイル データが 1 つのレコードになるようにしたいと考えています。http://yaseminavcular.blogspot.in/2011/03/many-small-input-files.htmlに従って、新しい API に変換しようとしました

私は2つの問題に直面しています:

a) 2 つの小さなファイルでテストしていますが、まだ 2 つのマッパーが起動しています。期待してた 1

b)各行は単一のレコードとして来ます。ファイル全体を単一のレコードとして欲しいです。

面倒かもしれませんが、以下のコードを見てください。私はまだhadoopの初心者です

ドライバークラス

public class MRDriver  extends Configured implements Tool {


@Override
public int run(String[] args) throws Exception {
    FileSystem fs = new Path(".").getFileSystem(getConf());
    fs.printStatistics();
    Job job = new Job(getConf());
    job.setJobName("Enron MR");
    job.setMapperClass(EnronMailReadMapper.class);
    job.setOutputKeyClass(Text.class);
    job.setOutputValueClass(IntWritable.class);
    job.setNumReduceTasks(0);
    job.setJarByClass(EnronMailReadMapper.class);
    RawCombineFileInputFormat.addInputPath(job, new Path(args[0]));
    job.setOutputFormatClass(TextOutputFormat.class);
    TextOutputFormat.setOutputPath(job, new Path(args[1]));
    return job.waitForCompletion(true) ? 0 :1;  
}

public static void main(String[] args) throws Exception  {
    int exitCode = ToolRunner.run(new MRDriver(), args);
    System.exit(exitCode);
}

}

以下のクラスは、主に LineRecordReader のコピペで、initialize() & nextKeyValue() 関数に変更を加えたものです

public class SingleFileRecordReader extends RecordReader<LongWritable, Text> {
  private static final Log LOG = LogFactory.getLog(SingleFileRecordReader.class);

  private long start;
  private long pos;
  private long end;
  private LineReader in;
  private int maxLineLength;
  private LongWritable key = null;
  private Text value = null;

  public void initialize(InputSplit genericSplit,
                         TaskAttemptContext context) throws IOException {
    FileSplit split = (FileSplit) genericSplit;
    Configuration job = context.getConfiguration();
    this.maxLineLength = job.getInt("mapred.linerecordreader.maxlength",
                                    Integer.MAX_VALUE);
    start = split.getStart();
    end = start + split.getLength();
    final Path file = split.getPath();

    // open the file and seek to the start of the split
    FileSystem fs = file.getFileSystem(job);
    FSDataInputStream fileIn = fs.open(split.getPath());

      fileIn.seek(start);
      in = new LineReader(fileIn, job);
    // If this is not the first split, we always throw away first record
    // because we always (except the last split) read one extra line in
    // next() method.
    if (start != 0) {
      start += in.readLine(new Text(), 0, maxBytesToConsume(start));
    }
    this.pos = start;
  }

  private int maxBytesToConsume(long pos) {
    return (int) Math.min(Integer.MAX_VALUE, end - pos);
  }

  private long getFilePosition() throws IOException {
    long retVal= pos;
    return retVal;
  }

  public boolean nextKeyValue() throws IOException {
    if (key == null) {
      key = new LongWritable();
    }
    key.set(pos);
    if (value == null) {
      value = new Text();
    }
    int newSize = 0;
    StringBuffer totalValue = new StringBuffer();
    // We always read one extra line, which lies outside the upper
    // split limit i.e. (end - 1)
    while (getFilePosition() <= end) {
      newSize = in.readLine(value, maxLineLength,
          Math.max(maxBytesToConsume(pos), maxLineLength));
      if (newSize == 0) {
        break;
      }
      totalValue.append(value.toString()+"\n");
      pos += newSize;
      if (newSize < maxLineLength) {
        break;
      }

      // line too long. try again
      LOG.info("Skipped line of size " + newSize + " at pos " + 
               (pos - newSize));
    }
    if (newSize == 0) {
      key = null;
      value = null;
      return false;
    } else {
        value = new Text(totalValue.toString());
      return true;
    }
  }

  @Override
  public LongWritable getCurrentKey() {
    return key;
  }

  @Override
  public Text getCurrentValue() {
    return value;
  }

  /**
   * Get the progress within the split
   */
  public float getProgress() throws IOException {
    if (start == end) {
      return 0.0f;
    } else {
      return Math.min(1.0f,
        (getFilePosition() - start) / (float)(end - start));
    }
  }

  public synchronized void close() throws IOException {
    try {
      if (in != null) {
        in.close();
      }
    } finally {

    }
  }

}

その他のファイル

public class RawCombineFileInputFormat extends CombineFileInputFormat <LongWritable,Text>{

@Override
public RecordReader<LongWritable, Text> createRecordReader(
        InputSplit split, TaskAttemptContext context) throws IOException {
    return new CombineFileRecordReader< LongWritable, Text >((CombineFileSplit) split, context, MultiFileRecordReader.class);
}

}

public class MultiFileRecordReader extends RecordReader < LongWritable, Text > {

 private CombineFileSplit split;
 private TaskAttemptContext context;
 private int index;
 private RecordReader< LongWritable, Text > rr;

public MultiFileRecordReader(CombineFileSplit split, TaskAttemptContext context, Integer index) {
    this.split = split;
    this.context = context;
    this.index = index;
    this.rr = new SingleFileRecordReader();
}
@Override
public void initialize(InputSplit split, TaskAttemptContext context)
        throws IOException, InterruptedException {
    this.split = (CombineFileSplit) split;
      this.context = context;

      if (null == rr) {
       rr = new SingleFileRecordReader();
      }

      FileSplit fileSplit = new FileSplit(this.split.getPath(index), 
                                          this.split.getOffset(index), 
                                          this.split.getLength(index), 
                                          this.split.getLocations());
      this.rr.initialize(fileSplit, this.context);

}

@Override
public boolean nextKeyValue() throws IOException, InterruptedException {
    // TODO Auto-generated method stub
    return this.rr.nextKeyValue();
}

@Override
public LongWritable getCurrentKey() throws IOException, InterruptedException {
    // TODO Auto-generated method stub
    return this.rr.getCurrentKey();
}

@Override
public Text getCurrentValue() throws IOException, InterruptedException {
    // TODO Auto-generated method stub
    return this.rr.getCurrentValue();
}

@Override
public float getProgress() throws IOException, InterruptedException {
    // TODO Auto-generated method stub
    return this.rr.getProgress();
}

@Override
public void close() throws IOException {
    if (rr != null) {
           rr.close();
           rr = null;
    }       
}   

}

4

1 に答える 1