Hadoop - 多输入

Question

我正在尝试使用来自 Hadoop 的 MultipleInputs。我所有的映射器都将是 FixedLengthInputFormat。

MultipleInputs.addInputPath(job, 
                    new Path(rootDir),       
                    FixedLengthInputFormat.class, 
                    OneToManyMapper.class);

问题是每个映射器都有不同大小的固定记录宽度。

config.setInt(FixedLengthInputFormat.FIXED_RECORD_LENGTH, ??);

是否有使用 MultipleInputs 为每个映射器传递 FIXED_RECORD_LENGTH 的方法？

谢谢！

Answer 1

解决办法如下：

public class CustomFixedLengthInputFormat extends FixedLengthInputFormat{

    @Override
    public RecordReader<LongWritable, BytesWritable> createRecordReader(
            InputSplit split, TaskAttemptContext context) throws IOException,
            InterruptedException {
        //here i can control de recordLength size!
        int recordLength = ??;// getRecordLength(context.getConfiguration());
        if (recordLength <= 0) {
            throw new IOException(
                    "Fixed record length "
                            + recordLength
                            + " is invalid.  It should be set to a value greater than zero");
        }

        System.out.println("Record Length: " + recordLength);

        return new FixedLengthRecordReader(recordLength);
    }

}