I am creating a simple hadoop sorting example, I have following code.
I am using ready-made InverseMaper and Identity reducer
FileInputFormat.setInputPaths(conf, new Path(args[0]));
FileOutputFormat.setOutputPath(conf, new Path(args[1]));
conf.setInputFormat(TextInputFormat.class);
conf.setOutputKeyClass(LongWritable.class);
conf.setOutputValueClass(LongWritable.class);
conf.setMapOutputKeyClass(LongWritable.class);
conf.setMapOutputValueClass(LongWritable.class);
conf.setMapperClass(InverseMapper.class);
conf.setReducerClass(IdentityReducer.class);
conf.setNumReduceTasks(1);
This is my input file data -
432
532
5234
43
65
524
15
56
96
25
3251
369845
58
249
354
When I run this code, I am getting following error. Could anyone help?
15/10/28 15:25:09 INFO mapred.LocalJobRunner: map task executor complete.
15/10/28 15:25:09 WARN mapred.LocalJobRunner: job_local2001686703_0001
java.lang.Exception: java.io.IOException: Type mismatch in key from map: expected org.apache.hadoop.io.LongWritable, received org.apache.hadoop.io.Text
at org.apache.hadoop.mapred.LocalJobRunner$Job.runTasks(LocalJobRunner.java:462)
at org.apache.hadoop.mapred.LocalJobRunner$Job.run(LocalJobRunner.java:522)
Caused by: java.io.IOException: Type mismatch in key from map: expected org.apache.hadoop.io.LongWritable, received org.apache.hadoop.io.Text
at org.apache.hadoop.mapred.MapTask$MapOutputBuffer.collect(MapTask.java:1069)
at org.apache.hadoop.mapred.MapTask$OldOutputCollector.collect(MapTask.java:607)
at org.apache.hadoop.mapred.lib.InverseMapper.map(InverseMapper.java:42)
at org.apache.hadoop.mapred.MapRunner.run(MapRunner.java:54)
at org.apache.hadoop.mapred.MapTask.runOldMapper(MapTask.java:450)
at org.apache.hadoop.mapred.MapTask.run(MapTask.java:343)
at org.apache.hadoop.mapred.LocalJobRunner$Job$MapTaskRunnable.run(LocalJobRunner.java:243)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
Copyright Notice：Content Author:「hard coder」，Reproduced under the CC 4.0 BY-SA copyright license with a link to the original source and this disclaimer.
Link to original article：https://stackoverflow.com/questions/33387929/type-mismatch-in-key-from-map-in-hadoop-sorting