Based on your stacktrace, the 'Task' did begin alright. (This is post-configuration/setup)
You're getting an NPE on metaFlickrPro\.PhotosDownload$MapClass\.map(PhotosDownload\.java:124) Its not possible for us to tell why since the point that was thrown is from your custom code - and we do not have that. I can't really tell if this is a framework issue with that trace. On Wed, May 25, 2011 at 9:21 PM, Michael Giannakopoulos <miccagi...@gmail.com> wrote: > Hello guys, > I have written an application that downloads metadata from 3 groups of > Flickr and i implement a map/reduce task so as metadata to be processed by 3 > different mappers (each corresponds to one group...). My app runs on single > mode, but when i try to run it in a pseudo-distributed mode hadoop keeps > showing me java.lang.NullPointerException. This happens before even the map > task starts. I suspect that something happens when the mapper tries to > create keys, or something with the encoding of the input file for the > mapper. Exception is the following one: > java.lang.NullPointerException > at metaFlickrPro.PhotosDownload$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
