关于Chukwa配置及运行实例，请参见：

Chukwa将收集到的数据以Sink Files的形式写入到HDFS中，如果不做Archive和Demux操作的话，默认存储在hdfs:///chukwa/logs目录下。

Sink File是Hadoop Sequence File，包含key-value集合。

其中key的类型为org.apache.hadoop.chukwa.ChukwaArchiveKey;

value的类型为org.apache.hadoop.chukwa.ChunkImpl.

一个完整的MapReduce过程可参考代码：

假定已经有Sequence File文件写入到hdfs:///chukwa/logs目录下，我们要对该文件做一个最基本的Word Count MapReduce操作。代码如下:

Tips: 读取Sequece File需要注明job.setInputFormatClass(SequenceFileInputFormat.class)

public class WordCount_SequenceFile {	public static class TokenizerMapper extends		Mapper
    
      {		private final static IntWritable one = new IntWritable(1);		private Text word = new Text();		public void map(ChukwaArchiveKey key, ChunkImpl value, Context context)				throws IOException, InterruptedException {						StringTokenizer itr = new StringTokenizer(new String(value.getData()));						while (itr.hasMoreTokens()) {				word.set(itr.nextToken());				context.write(word, one);			}		}	}	public static class IntSumReducer extends		Reducer
     
       {		private IntWritable result = new IntWritable();		public void reduce(Text key, Iterable
      
        values,				Context context) throws IOException, InterruptedException {			int sum = 0;			for (IntWritable val : values) {				sum += val.get();			}			result.set(sum);			context.write(key, result);		}	}	public static void main(String[] args) throws Exception {		Configuration conf = new Configuration();		String[] otherArgs = new GenericOptionsParser(conf, args)				.getRemainingArgs();		if (otherArgs.length != 2) {			System.err.println("Usage: wordcount 
        
        
         ");			System.exit(2);		}		@SuppressWarnings("deprecation")		Job job = new Job(conf, "word count");		job.setJarByClass(WordCount_SequenceFile.class);		job.setInputFormatClass(SequenceFileInputFormat.class);		 		job.setMapperClass(TokenizerMapper.class);		job.setCombinerClass(IntSumReducer.class);		job.setReducerClass(IntSumReducer.class);		job.setOutputKeyClass(Text.class);		job.setOutputValueClass(IntWritable.class);		FileInputFormat.addInputPath(job, new Path(otherArgs[0]));		FileOutputFormat.setOutputPath(job, new Path(otherArgs[1]));		System.exit(job.waitForCompletion(true) ? 0 : 1);	}}
        
       
      
     
    

在运行时需要添加chukwa-0.5.0.jar库：

hadoop jar MapReduce.jar demo.mapreduce.WordCount_SequenceFile-libjars MapReduce.jar,chukwa-0.5.0.jar /chukwa/logs/xx.done /output_file