Okay, I got it now. You were talking about your programs but not the
PiEstimator example came from Hadoop. Then, you have to set
"mapred.output.key.class" and "mapred.output.value.class" as Srihari mentioned.
Below are the APIs.
//new API
final Job job = ...
job.setMapOutputKeyClass(BooleanWritable.class);
job.setMapOutputValueClass(LongWritable.class);
//old API
final JobConf jobconf = ...
jobconf.setOutputKeyClass(BooleanWritable.class);
jobconf.setOutputValueClass(LongWritable.class);
Nicholas
________________________________
From: Srihari Anantha Padmanabhan <sriha...@yahoo-inc.com>
To: "mapreduce-user@hadoop.apache.org" <mapreduce-user@hadoop.apache.org>
Sent: Wed, January 26, 2011 10:36:09 AM
Subject: Re: PiEstimator error - Type mismatch in key from map
I am using Hadoop 0.20.2. I just wrote my own map-reduce program based on the
map-reduce tutorial at
http://hadoop.apache.org/common/docs/r0.20.2/mapred_tutorial.html
On Jan 26, 2011, at 10:27 AM, Pedro Costa wrote:
> Hadoop 20.1
>
> On Wed, Jan 26, 2011 at 6:26 PM, Tsz Wo (Nicholas), Sze
> <s29752-hadoopu...@yahoo.com> wrote:
>> Hi Srihari,
>>
>> Same questions to you: Which version of Hadoop are you using? And where did
>> you get the examples? I guess you were able to reproduce it. I suspect the
>> examples and the Hadoop are in different versions.
>>
>> Nicholas
>>
>>
>> ________________________________
>> From: Srihari Anantha Padmanabhan <sriha...@yahoo-inc.com>
>> To: "mapreduce-user@hadoop.apache.org" <mapreduce-user@hadoop.apache.org>
>> Sent: Wed, January 26, 2011 10:15:08 AM
>> Subject: Re: PiEstimator error - Type mismatch in key from map
>>
>> I got a similar error before in one of my projects. I had to set the values
>> for "mapred.output.key.class" and "mapred.output.value.class".
>> That resolved the issue for me.
>> Srihari
>> On Jan 26, 2011, at 10:09 AM, Pedro Costa wrote:
>>
>> Yes, I can reproduce it deterministically. But, I also did some
>> changes to the Hadoop MR code. Most definitely this is the reason. I'm
>> looking throughly through the code.
>>
>> I'll say something after I find the problem.
>>
>> I was just wondering if this error has happened to someone before.
>> Maybe I could get a hint and try to see what's my problem easily.
>>
>> Thanks,
>>
>> On Wed, Jan 26, 2011 at 6:02 PM, Tsz Wo (Nicholas), Sze
>> <s29752-hadoopu...@yahoo.com> wrote:
>>
>> Hi Pedro,
>>
>> This is interesting. Which version of Hadoop are you using? And where did
>>
>> you get the example class files? Also, are you able to reproduce it
>>
>> deterministically?
>>
>> Nicholas
>>
>> ________________________________
>>
>> From: Pedro Costa <psdc1...@gmail.com>
>>
>> To: mapreduce-user@hadoop.apache.org
>>
>> Sent: Wed, January 26, 2011 5:47:01 AM
>>
>> Subject: PiEstimator error - Type mismatch in key from map
>>
>> Hi,
>>
>> I run the PI example of hadoop, and I've got the following error:
>>
>> [code]
>>
>> java.io.IOException: Type mismatch in key from map: expected
>>
>> org.apache.hadoop.io.BooleanWritable, recieved
>>
>> org.apache.hadoop.io.LongWritable
>>
>> at
>>
>> org.apache.hadoop.mapred.MapTask$MapOutputBuffer.collect(MapTask.java:885)
>>
>> at
>>
>> org.apache.hadoop.mapred.MapTask$NewOutputCollector.write(MapTask.java:551)
>>
>> at
>>
>>org.apache.hadoop.mapreduce.TaskInputOutputContext.write(TaskInputOutputContext.java:81)
>>)
>>
>> at org.apache.hadoop.mapreduce.Mapper.map(Mapper.java:124)
>>
>> at org.apache.hadoop.mapreduce.Mapper.run(Mapper.java:144)
>>
>> at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:637)
>>
>> at org.apache.hadoop.mapred.MapTask.run(MapTask.java:343)
>>
>> at org.apache.hadoop.mapred.Child.main(Child.java:190)
>>
>> [/code]
>>
>> I've look at the map function of the class "PiEstimator.class" and it seems
>>
>> ok.
>>
>> [code]
>>
>> public void map(LongWritable offset,
>>
>> LongWritable size,
>>
>> OutputCollector<BooleanWritable, LongWritable> out,
>>
>> Reporter reporter) throws IOException {}
>>
>> [/code]
>>
>>
>> What's wrong with this examples?
>>
>> Thanks,
>>
>> --
>>
>> Pedro
>>
>>
>>
>>
>> --
>> Pedro
>>
>>
>
>
>
> --
> Pedro
