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我的 cassandra scehma 在列族中只有一行。运行 mapreduce 时，映射器会一次又一次地读取同一行。因此，mapper 进入无穷大，reducer 卡住了....

这些是使用的配置

conf.set("fs.default.name", "hdfs://28.151.181.107:9000");
    conf.set("mapred.job.tracker", "28.151.181.107:9001");
    conf.setJar("C:\\hadoop-test\\demo\\target\\demo-0.0.1-SNAPSHOT.jar");

    conf.setMapperClass(TokenizerMapper.class);
    conf.setCombinerClass(ReducerToFilesystem.class);
    conf.setReducerClass(ReducerToFilesystem.class);
    conf.setOutputKeyClass(Text.class);
    conf.setOutputValueClass(Text.class);
    conf.setMapOutputKeyClass(Text.class);
    conf.setMapOutputValueClass(Text.class);

    FileOutputFormat.setOutputPath(conf, new Path(resultFileName));

    conf.setInputFormat(ColumnFamilyInputFormat.class);

    ConfigHelper.setInputRpcPort(conf, PORT + "");
    ConfigHelper.setInputInitialAddress(conf, HOST);
    ConfigHelper.setInputPartitioner(conf, "RandomPartitioner");
    ConfigHelper.setInputColumnFamily(conf, KEY_SPACE, COLUMN_FAMILY,true);
    SlicePredicate predicate = new SlicePredicate();
    SliceRange sliceRange = new SliceRange();
    sliceRange.setStart(new byte[0]);
    sliceRange.setFinish(new byte[0]);
    predicate.setSlice_range(sliceRange);
    ConfigHelper.setInputSlicePredicate(conf, predicate);
    ConfigHelper.setOutputInitialAddress(conf, HOST);
    ConfigHelper.setOutputPartitioner(conf, "RandomPartitioner");

和 Mapper & Reducer 是

public void map(ByteBuffer key, SortedMap<ByteBuffer, IColumn> columns,
            OutputCollector<Text, Text> paramOutputCollector,
            Reporter paramReporter) throws IOException {

        DateSerializer sz = new DateSerializer();
        StringSerializer s = new StringSerializer();

        for (IColumn col : columns.values()) {
            Date name = sz.fromByteBuffer(col.name());

            double value = ByteBufferUtil.toDouble(col.value());
            paramOutputCollector.collect(new Text(s.fromByteBuffer(key)),
                    new Text(name.toGMTString() + " [] []  " + value));
        }

    }


public static class ReducerToFilesystem implements
        Reducer<Text, Text, Text, Text> {
    public void reduce(Text key, Iterator<Text> values,
            OutputCollector<Text, Text> paramOutputCollector,
            Reporter paramReporter) throws IOException {
        StringBuffer bfr = new StringBuffer();
        while (values.hasNext()) {
            Text val = values.next();
            bfr.append(val);
            bfr.append("<--->");

        }

        paramOutputCollector.collect(key, new Text(bfr.toString()));

    }

请指导。

谢谢您的帮助！

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1 回答 1

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我已经调试了一下，我认为你是对的。即使在 1.2.9 版本中，分页也没有正确完成。

于 2013-09-30T18:40:22.883 回答