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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

You're getting an NPE on
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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