Question

我尝试使用Amazon EMR分析Wikipedia article view dataset。此数据集包含三个月期间（2011年1月1日至2011年3月31日）的页面查看统计信息。我试图找到那段时间内观点最多的文章。这是我正在使用的代码：

public class mostViews {

public static class Map extends MapReduceBase implements Mapper<LongWritable, Text, Text, IntWritable> {

    private final static IntWritable views = new IntWritable(1);
    private Text article = new Text();

    public void map(LongWritable key, Text value, OutputCollector<Text, IntWritable> output, Reporter reporter) throws IOException {

        String line = value.toString();

        String[] words = line.split(" ");
        article.set(words[1]);
        views.set(Integer.parseInt(words[2]));
        output.collect(article, views);
    }
}

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 Exception {
    JobConf conf = new JobConf(mostViews.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);
}
}

代码本身可以工作，但是当我创建一个集群并添加一个自定义jar时，它有时会失败，但有时会失败。使用整个数据集作为输入会导致它失败，但使用一个月，例如1月，它就会完成。在使用整个数据集运行后，我查看了控制器＆＃39;日志文件并找到了这个，我认为是相关的：

2015-03-10T11:50:12.437Z INFO Synchronously wait child process to complete :     hadoop jar /mnt/var/lib/hadoop/steps/s-22ZUAWNM...
2015-03-10T12:05:10.505Z INFO Process still running
2015-03-10T12:20:12.573Z INFO Process still running
2015-03-10T12:35:14.642Z INFO Process still running
2015-03-10T12:50:16.711Z INFO Process still running
2015-03-10T13:05:18.779Z INFO Process still running
2015-03-10T13:20:20.848Z INFO Process still running
2015-03-10T13:35:22.916Z INFO Process still running
2015-03-10T13:50:24.986Z INFO Process still running
2015-03-10T14:05:27.056Z INFO Process still running
2015-03-10T14:20:29.126Z INFO Process still running
2015-03-10T14:35:31.196Z INFO Process still running
2015-03-10T14:50:33.266Z INFO Process still running
2015-03-10T15:05:35.337Z INFO Process still running
2015-03-10T15:11:37.366Z INFO waitProcessCompletion ended with exit code 1 :     hadoop jar /mnt/var/lib/hadoop/steps/s-22ZUAWNM...
2015-03-10T15:11:40.064Z INFO Step created jobs: job_1425988140328_0001
2015-03-10T15:11:50.072Z WARN Step failed as jobs it created failed.     Ids:job_1425988140328_0001

有谁能告诉我出了什么问题，我能做些什么来解决它？它工作一个月而不是两三个月的事实让我觉得数据集可能太大了，但我不确定。我对这整个Hadoop / EMR事物还是新手，所以如果我遗漏了任何信息，请告诉我。任何帮助或建议将不胜感激。

提前致谢！

Answer 1

这些错误通常发生在HDFS（EMR节点的硬盘）或内存空间不足时。

首先，我首先尝试阅读消息指示您的日志：“/ mnt / var / lib / hadoop / steps / s-22ZUAWNM ......”

其次，我会尝试创建更大的EMR（具有更多磁盘和RAM或更多核心实例的EC2实例）。

AWS EMR步骤失败，因为它创建的作业失败

1 个答案: