为什么“ set”只有一个元素,而对于前5行输入,它应该具有4个元素,它们具有相同的URL和四个不同的IP。我也使用“ for-each”代替“ iterator”,但是不起作用。有人可以帮我吗?
映射器
public class WordCount {
public static class TokenizerMapper extends Mapper<Object, Text, Text, Text> {
private Text IP = new Text();
private Text word = new Text();
public void map(Object key, Text value, Context context) throws IOException, InterruptedException {
String line = value.toString();
String[] tokens = line.split(",");
word.set(tokens[2]);
IP.set(tokens[0]);
context.write(word, IP);
}
}
减速器
public static class IntSumReducer extends Reducer<Text, Text, Text, Text> {
public void reduce(Text key, Iterable<Text> values, Context context) throws IOException, InterruptedException {
Set<String> set = new HashSet<String>();
Iterator<Text> iterator = values.iterator();
while (iterator.hasNext()) {
set.add(iterator.next().toString());
}
int a = set.size();
String str = String.format("%d", a);
context.write(key, new Text(str));
}
}
工作
public static void main(String[] args) throws Exception {
Job job = new Job();
job.setJarByClass(WordCount.class);
job.setMapperClass(TokenizerMapper.class);
job.setCombinerClass(IntSumReducer.class);
job.setReducerClass(IntSumReducer.class);
job.setOutputKeyClass(Text.class);
job.setOutputValueClass(Text.class);
FileInputFormat.addInputPath(job, new Path(args[0]));
FileOutputFormat.setOutputPath(job, new Path(args[1]));
System.exit(job.waitForCompletion(true) ? 0 : 1);
}
}
输入
"10.131.0.1","[29/Nov/2017:14:31:33","GET / HTTP/1.1","200"
"10.131.0.2","[29/Nov/2017:14:31:38","GET / HTTP/1.1","200"
"10.131.0.3","[29/Nov/2017:14:31:56","GET / HTTP/1.1","200"
"10.131.0.4","[29/Nov/2017:14:32:02","GET / HTTP/1.1","404"
"10.131.0.5","[29/Nov/2017:16:31:39","GET / HTTP/1.1","200"
"10.131.0.1","[29/Nov/2017:14:05:35","GET /contest.php HTTP/1.1","200"
"10.131.0.2","[29/Nov/2017:14:05:38","GET /contest.php HTTP/1.1","200"
"10.131.0.3","[29/Nov/2017:14:05:50","GET /contest.php HTTP/1.1","404"
"10.131.0.1","[29/Nov/2017:13:51:41","GET /login.php HTTP/1.1","200"
"10.131.0.2","[29/Nov/2017:13:51:49","GET /login.php HTTP/1.1","200"
"10.131.0.1","[29/Nov/2017:13:51:46","GET /contestproblem.php?name=RUET%20OJ%20Server%20Testing%20Contest HTTP/1.1","200"
"10.131.0.8","[29/Nov/2017:13:51:46","GET /contestproblen.php?name=RUET%20OJ%20Server%20Testing%20Contest HTTP/1.1","200"
我的结果是
"GET / HTTP/1.1" 1
"GET /contest.php HTTP/1.1" 1
"GET /contestproblem.php?name=RUET%20OJ%20Server%20Testing%20Contest HTTP/1.1" 1
"GET /contestproblen.php?name=RUET%20OJ%20Server%20Testing%20Contest HTTP/1.1" 1
"GET /login.php HTTP/1.1" 1
答案 0 :(得分:0)
Reducer工作正常,但是Combiner并未按照您的想法进行。启用合并器的过程是:
地图输出:
("GET / HTTP/1.1", "10.31.0.1")
("GET / HTTP/1.1", "10.31.0.2")
COMBINER输入:
("GET / HTTP/1.1", {"10.31.0.1", "10.31.0.2"})
COMBINER输出:
("GET / HTTP/1.1", "2") //You have the right answer here...
减速器输入:
("GET / HTTP/1.1", {"2"}) //...but then it gets passed into the Reducer again
减速机输出:
("GET / HTTP/1.1", "1")
只有一个元素进入减速器,因此它将减小为“ 1”。
删除组合器(删除job.setCombinerClass(IntSumReducer.class);
,这将起作用。
其他建议的更改:
IntWritable
,而不是将数字转换为Text
。Set
设为Set<Text>
而不是Set<String>
,以节省昂贵的Text -> String
转换。