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From Harsh J <ha...@cloudera.com>
Subject Re: Map Reduce when downloading files...
Date Wed, 25 May 2011 15:57:51 GMT
Based on your stacktrace, the 'Task' did begin alright. (This is
post-configuration/setup)

You're getting an NPE on
metaFlickrPro\.PhotosDownload$MapClass\.map(PhotosDownload\.java:124)
Its not possible for us to tell why since the point that was thrown is
from your custom code - and we do not have that.
I can't really tell if this is a framework issue with that trace.

On Wed, May 25, 2011 at 9:21 PM, Michael Giannakopoulos
<miccagiann@gmail.com> wrote:
> Hello guys,
> I have written an application that downloads metadata from 3 groups of
> Flickr and i implement a map/reduce task so as metadata to be processed by 3
> different mappers (each corresponds to one group...). My app runs on single
> mode, but when i try to run it in a pseudo-distributed mode hadoop keeps
> showing me java.lang.NullPointerException. This happens before even the map
> task starts. I suspect that something happens when the mapper tries to
> create keys, or something with the encoding of the input file for the
> mapper. Exception is the following one:
> java.lang.NullPointerException
>     at metaFlickrPro.PhotosDownload$MapClass.map(PhotosDownload.java:124)
>     at metaFlickrPro.PhotosDownload$MapClass.map(PhotosDownload.java:1)
>     at org.apache.hadoop.mapreduce.Mapper.run(Mapper.java:144)
>     at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:621)
>     at org.apache.hadoop.mapred.MapTask.run(MapTask.java:305)
>     at org.apache.hadoop.mapred.Child.main(Child.java:170)
>
> where "metaFlickrPro" is the package of my application and PhotosDownload is
> the public class that contains the static classes of mapper and reducer...
> Please, if anyone has encountered a similar problem, i would be grateful if
> he/she answered. I have attached the log file from the map-reduce process. I
> run hadoop 0.20.2 on Ubuntu 10.04...
>



-- 
Harsh J

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