我有四个类,MapperOne,ReducerOne,MapperTwo,ReducerTwo . 我想要一个链 . MapperOne - > ReducerOne - >输出文件生成,输入到MapperTwo - > MapperTwo - > ReducerTwo - >最终输出文件 .
我的驾驶员课程代码:
public class StockDriver {
public static void main(String[] args) throws IOException, InterruptedException, ClassNotFoundException {
System.out.println(" Driver invoked------");
Configuration config = new Configuration();
config.set("mapreduce.input.keyvaluelinerecordreader.key.value.separator", " ");
config.set("mapred.textoutputformat.separator", " --> ");
String inputPath="In\\NYSE_daily_prices_Q_less.csv";
String outpath = "C:\\Users\\Outputs\\run1";
String outpath2 = "C:\\UsersOutputs\\run2";
Job job1 = new Job(config,"Stock Analysis: Creating key values");
job1.setInputFormatClass(TextInputFormat.class);
job1.setOutputFormatClass(TextOutputFormat.class);
job1.setMapOutputKeyClass(Text.class);
job1.setMapOutputValueClass(StockDetailsTuple.class);
job1.setOutputKeyClass(Text.class);
job1.setOutputValueClass(Text.class);
job1.setMapperClass(StockMapperOne.class);
job1.setReducerClass(StockReducerOne.class);
FileInputFormat.setInputPaths(job1, new Path(inputPath));
FileOutputFormat.setOutputPath(job1, new Path(outpath));
//THE SECOND MAP_REDUCE TO DO CALCULATIONS
Job job2 = new Job(config,"Stock Analysis: Calculating Covariance");
job2.setInputFormatClass(TextInputFormat.class);
job2.setOutputFormatClass(TextOutputFormat.class);
job2.setMapOutputKeyClass(LongWritable.class);
job2.setMapOutputValueClass(Text.class);
job2.setOutputKeyClass(Text.class);
job2.setOutputValueClass(Text.class);
job2.setMapperClass(StockMapperTwo.class);
job2.setReducerClass(StockReducerTwo.class);
String outpath3=outpath+"\\part-r-00000";
System.out.println("OUT PATH 3: " +outpath3 );
FileInputFormat.setInputPaths(job2, new Path(outpath3));
FileOutputFormat.setOutputPath(job2, new Path(outpath2));
if(job1.waitForCompletion(true)){
System.out.println(job2.waitForCompletion(true));
}
}
}
我的MapperOne和ReducerOne正在正确执行,输出文件存储在正确的路径中 . 现在,当执行第二个作业时,仅调用reducer . 下面是我的MapperTwo和ReducerTwo代码 .
MAPPER TWO
公共类StockMapperTwo扩展Mapper {
public void map(LongWritable key, Iterable<Text> values, Context context) throws IOException, InterruptedException{
System.out.println("------ MAPPER 2 CALLED-----");
for(Text val: values){
System.out.println("KEY: "+ key.toString() + " VALUE: "+ val.toString());
//context.write(new Text("mapper2"), new Text("hi"));
context.write(new LongWritable(2), new Text("hi"));
}
}
}
REDUCER TWO
public class StockReducerTwo extends Reducer<LongWritable, Text, Text, Text>{
public void reduce(LongWritable key, Iterable<Text>values, Context context) throws IOException, InterruptedException{
System.out.println(" REDUCER 2 INVOKED");
context.write(new Text("hello"), new Text("hi"));
}
}
我对这个配置有疑问
-
为什么跳过映射器,即使它在job2.setMapperClass(StockMapperTwo.class)中设置了;
-
如果我没有设置job2.setMapOutputKeyClass(LongWritable.class); job2.setMapOutputValueClass(Text.class);然后甚至不调用reducer . 而这个错误即将到来 .
java.io.IOException:在map中键入mismatch:expected org.apache.hadoop.io.Text,在org.apache.hadoop.mapred.MapTask收到org.apache.hadoop.io.LongWritable $ MapOutputBuffer.collect(MapTask .java:870)在org.apache的org.apache.hadoop.mapred.MapTask $ NewOutputCollector.write(MapTask.java:573)org.apache.hadoop.mapreduce.TaskInputOutputContext.write(TaskInputOutputContext.java:80) . org.apache.hadoop.mapreduce.Mapper.run中的hadoop.mapreduce.Mapper.map(Mapper.java:124)(Mapper.java:144)
这是怎么回事?请帮忙 . 我无法正确调用我的mapper和reducer . 请指导我 .
1 回答
很抱歉发布此问题 . 我没有注意到我的映射器编写错误 .
这是一个问题
我保持这样
我花了很多时间来观察这个错误 . 我不确定为什么没有错误来表明错误 . 无论如何它现在解决了 .