This was answered at http://search-hadoop.com/m/j1M3R1Mjjx31
On Fri, Aug 3, 2012 at 3:52 AM, Harit Himanshu <harit.himan...@gmail.com> wrote:
> Hi,
>
> I face another issue, now, Here is my program
>
>
> public static class MapClass extends Mapper<LongWritable, Text, Text,
> LongWritable> {
>
> public void map(LongWritable key, Text value, Context context)
> throws IOException, InterruptedException {
> // your map code goes here
> String[] fields = value.toString().split(",");
> Text yearInText = new Text();
> LongWritable out = new LongWritable();
> String year = fields[1];
> String claims = fields[8];
>
> if (claims.length() > 0 && (!claims.startsWith("\""))) {
> yearInText.set(year.toString());
> out.set(Long.parseLong(claims));
> context.write(yearInText, out);
> }
> }
> }
>
>
> public static class Reduce extends Reducer<Text, LongWritable, Text,
> Text> {
>
> public void reduce(Text key, Iterable<LongWritable> values, Context
> context) throws IOException, InterruptedException {
> // your reduce function goes here
> Text value = new Text();
> value.set(values.toString());
> context.write(key, value);
> }
> }
>
> public int run(String args[]) throws Exception {
> Job job = new Job();
> job.setJarByClass(TopKRecord.class);
>
> job.setMapperClass(MapClass.class);
> job.setReducerClass(Reduce.class);
>
> FileInputFormat.setInputPaths(job, new Path(args[0]));
> FileOutputFormat.setOutputPath(job, new Path(args[1]));
>
> job.setMapOutputValueClass(LongWritable.class);
> job.setJobName("TopKRecord");
>
> // job.setNumReduceTasks(0);
> boolean success = job.waitForCompletion(true);
> return success ? 0 : 1;
> }
>
> public static void main(String args[]) throws Exception {
> int ret = ToolRunner.run(new TopKRecord(), args);
> System.exit(ret);
> }
> }
>
> When I run this in hadoop, I see the following error
>
> 12/08/02 15:12:59 INFO mapred.JobClient: Task Id :
> attempt_201208021025_0011_m_000001_0, Status : FAILED
> java.io.IOException: Type mismatch in key from map: expected
> org.apache.hadoop.io.LongWritable, recieved org.apache.hadoop.io.Text
> at
> org.apache.hadoop.mapred.MapTask$MapOutputBuffer.collect(MapTask.java:1014)
> at
> org.apache.hadoop.mapred.MapTask$NewOutputCollector.write(MapTask.java:691)
> at
> org.apache.hadoop.mapreduce.TaskInputOutputContext.write(TaskInputOutputContext.java:80)
> at com.hadoop.programs.TopKRecord$MapClass.map(TopKRecord.java:39)
> at com.hadoop.programs.TopKRecord$MapClass.map(TopKRecord.java:26)
> at org.apache.hadoop.mapreduce.Mapper.run(Mapper.java:144)
> at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:764)
> at org.apache.hadoop.mapred.MapTask.run(MapTask.java:370)
> at org.apache.hadoop.mapred.Child$4.run(Child.java:255)
> at java.security.AccessController.doPrivileged(Native Method)
> at javax.security.auth.Subject.doAs(Subject.java:396)
> at
> org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1121)
> at org.apache.hadoop.mapred.Child.main(Child.java:249)
>
> I asked this question on SO, and got response that I need to
> setMapOutputValue class and I tried that too (see in code above) by
> following
> http://hadoop.apache.org/common/docs/r0.20.2/api/org/apache/hadoop/mapreduce/Job.html#setMapOutputKeyClass%28java.lang.Class%29
>
> How do I fix this?
>
> Thank you
> + Harit
--
Harsh J
