java - 如何在 Hortonworks 沙盒 Hadoop 平台中运行 mapreduce 作业

Question

我是 Hadoop 的新手。我已经为虚拟机安装了 oracle 虚拟机并安装了 hortonworks 沙箱的图像。我还在 eclipse 中编写了 wordcount 程序并尝试在虚拟机中运行它。但是我得到了一个异常树。我也在发布程序和错误树。

public class WordCount {

public static class Map extends MapReduceBase implements
        Mapper<LongWritable, Text, Text, IntWritable> {
    private final static IntWritable one = new IntWritable(1);
    private Text word = new Text();

    public void map(LongWritable key, Text value,
            OutputCollector<Text, IntWritable> output, Reporter reporter)
            throws IOException {
        String line = value.toString();
        StringTokenizer tokenizer = new StringTokenizer(line);
        while (tokenizer.hasMoreTokens()) {
            word.set(tokenizer.nextToken());
            output.collect(word, one);
        }
    }
}

public static class Reduce extends MapReduceBase implements
        Reducer<Text, IntWritable, Text, IntWritable> {
    public void reduce(Text key, Iterator<IntWritable> values,
            OutputCollector<Text, IntWritable> output, Reporter reporter)
            throws IOException {
        int sum = 0;
        while (values.hasNext()) {
            sum += values.next().get();
        }
        output.collect(key, new IntWritable(sum));
    }
}

public static void main(String[] args) throws IOException {
    JobConf conf = new JobConf(WordCount.class);
    conf.setJobName("wordcount");

    conf.setOutputKeyClass(Text.class);
    conf.setOutputValueClass(IntWritable.class);

    conf.setMapperClass(Map.class);
    conf.setCombinerClass(Reduce.class);
    conf.setReducerClass(Reduce.class);

    conf.setInputFormat(TextInputFormat.class);
    conf.setOutputFormat(TextOutputFormat.class);

    FileInputFormat.setInputPaths(conf, new Path(args[0]));
    FileOutputFormat.setOutputPath(conf, new Path(args[1]));

    JobClient.runJob(conf);

}

}

[hue@sandbox`]$hadoop jar/usr/lib/wordcount.jar wordcount[-m][-r]

线程主 java.lang.NoClassDefFoundError:jar/usr/lib/wordcount/jar 中的异常

引起:java.lang.ClassNotFoundException:jar.usr.lib.wordcount.jar
在 java.net.URLClassLoader$1.run(URLlassLoader.java:202)
在 java.security.AccessController.doPriviledged( native 方法)
在 java.net.URLClassLoader.findClass(URLClassLoader.java:190)
在 java.lang.ClassLoader.loadClass(ClassLoader.java:306)
在 sun.misc.Launcher$AppClassLoader.loadClass(Laucher.java:301)
在 java.lang.ClassLoader.loadClass(ClassLoader.java:247)

找不到主类:jar/usr/lib/wordcount.jar



我在 64 位机器上使用 Hortonworks+Sandbox+1.3+VirtualBox+RC6 这个版本。

Answer 1

您没有正确调用 hadoop，您缺少空格以及 args。尝试

hadoop jar /usr/lib/wordcount.jar WordCount <the path to your input file on HDFS> <the path to your output directory on HDFS>

如果找不到其他类，请尝试使用 WordCount 的完整类名(例如 com.mysite.WordCount)。我看不到它在什么包装中。