已经检查了这一点,我无法理解为什么会遇到这个错误。
映射
public class movieMapper extends Mapper<LongWritable, Text, IntWritable, Text> {
public void map(LongWritable key, Text value, Context context ) throws IOException,InterruptedException {
String token[]= value.toString().trim().split("::");
int movieID=Integer.parseInt(token[0].trim());
context.write(new IntWritable(movieID), new Text(token[1].trim()));
}
}
减速
public class joinReducer extends Reducer<IntWritable, Text, Text, Text> {
public void reduce(IntWritable key, Iterable<Text> values, Context context) throws IOException,InterruptedException {
float avgRating=0.0f;
int tokenCount = 0;
float ratingSum=0.0f;
int count=0;
String movieName="";
for(Text val:values) {
tokenCount+=1;
}
//If we have more than 40 views/ratings
if(tokenCount-1>40) {
for(Text val:values) {
String temp = val.toString();
if(val.equals("1")||val.equals("2")||val.equals("3")||val.equals("4")||val.equals("5")) {
float tempRating= Float.parseFloat(val.toString().trim());
ratingSum += tempRating;
count++;
}
else {
movieName=val.toString().trim();
}
}
avgRating = ratingSum/ (float)count;
context.write(new Text(Float.toString(avgRating)), new Text(movieName));
}
}
}
驱动程序配置
Configuration conf= new Configuration();
String parameter[]= new GenericOptionsParser(conf,args).getRemainingArgs();
if(parameter.length!=3) {
System.err.println("Three arguments needed <File1> <File2> <Out>");
System.exit(2);
}
//set Driver class
Job job1 = Job.getInstance(conf, "Join");
job1.setJarByClass(MyDriver.class);
job1.setReducerClass(joinReducer.class);
MultipleInputs.addInputPath(job1, new Path(parameter[0]), TextInputFormat.class, movieMapper.class);
MultipleInputs.addInputPath(job1, new Path(parameter[1]), TextInputFormat.class, ratingMapper.class);
job1.setMapOutputKeyClass(IntWritable.class);
job1.setMapOutputValueClass(Text.class);
job1.setOutputKeyClass(Text.class);
job1.setOutputValueClass(Text.class);
FileOutputFormat.setOutputPath(job1, new Path(parameter[2] + "/temp"));
job1.waitForCompletion(true);
18/06/13 09:47:20 INFO mapreduce.Job:在uber模式下运行的job job_1528823320386_0018:false 18/06/13 09:47:20 INFO mapreduce.Job:地图0%减少0% 18/06/13 09:47:24 INFO mapreduce.Job:任务ID:attempt_1528823320386_0018_m_000000_0,状态:未通过 错误:java.io.IOException:键入map中的键不匹配:expected org.apache.hadoop.io.IntWritable,收到org.apache.hadoop.io.LongWritable at org.apache.hadoop.mapred.MapTask $ MapOutputBuffer.collect(MapTask.java:1069) at org.apache.hadoop.mapred.MapTask $ NewOutputCollector.write(MapTask.java:712) at org.apache.hadoop.mapreduce.task.TaskInputOutputContextImpl.write(TaskInputOutputContextImpl.java:89) at org.apache.hadoop.mapreduce.lib.map.WrappedMapper $ Context.write(WrappedMapper.java:112) 在org.apache.hadoop.mapreduce.Mapper.map(Mapper.java:124) 在org.apache.hadoop.mapreduce.Mapper.run(Mapper.java:145) 在org.apache.hadoop.mapreduce.lib.input.DelegatingMapper.run(DelegatingMapper.java:55) 在org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:784) 在org.apache.hadoop.mapred.MapTask.run(MapTask.java:341) 在org.apache.hadoop.mapred.YarnChild $ 2.run(YarnChild.java:168) at java.security.AccessController.doPrivileged(Native Method) 在javax.security.auth.Subject.doAs(Subject.java:422) at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1642) 在org.apache.hadoop.mapred.YarnChild.main(YarnChild.java:163)
18/06/13 09:47:25 INFO mapreduce.Job:地图50%减少0% 18/06/13 09:47:29 INFO mapreduce.Job:任务ID:attempt_1528823320386_0018_m_000000_1,状态:未通过 错误:java.io.IOException:键入map中的键不匹配:expected org.apache.hadoop.io.IntWritable,收到org.apache.hadoop.io.LongWritable at org.apache.hadoop.mapred.MapTask $ MapOutputBuffer.collect(MapTask.java:1069) at org.apache.hadoop.mapred.MapTask $ NewOutputCollector.write(MapTask.java:712) at org.apache.hadoop.mapreduce.task.TaskInputOutputContextImpl.write(TaskInputOutputContextImpl.java:89) at org.apache.hadoop.mapreduce.lib.map.WrappedMapper $ Context.write(WrappedMapper.java:112) 在org.apache.hadoop.mapreduce.Mapper.map(Mapper.java:124) 在org.apache.hadoop.mapreduce.Mapper.run(Mapper.java:145) 在org.apache.hadoop.mapreduce.lib.input.DelegatingMapper.run(DelegatingMapper.java:55) 在org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:784) 在org.apache.hadoop.mapred.MapTask.run(MapTask.java:341) 在org.apache.hadoop.mapred.YarnChild $ 2.run(YarnChild.java:168) at java.security.AccessController.doPrivileged(Native Method) 在javax.security.auth.Subject.doAs(Subject.java:422) at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1642) 在org.apache.hadoop.mapred.YarnChild.main(YarnChild.java:163)
答案 0 :(得分:0)
这个作业中有两个映射器,即movieMapper和ratingMapper。 ratingMapper在函数声明中拼写错误的关键字和地图函数的名称&#39; map&#39;被错误地写为&#39; reduce&#39;。
根据out配置,reducer应该接受IntWritable类型的键,但是得到LongWritable,因此错误。 (TextInputFormat生成LongWritable类型的键和Text类型的值)