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From Srihari Anantha Padmanabhan <sriha...@yahoo-inc.com>
Subject Re: PiEstimator error - Type mismatch in key from map
Date Wed, 26 Jan 2011 18:36:09 GMT
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-hadoopuser@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 <sriharia@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-hadoopuser@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 <psdc1978@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


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