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From Denim Live <denim.l...@yahoo.com>
Subject Distributed Cache file issue
Date Thu, 08 Jul 2010 19:02:03 GMT
Hello all,

As a new user of hadoop, I am having some problems with understanding some 
things. I am writing a program to load a file to the distributed cache and read 
this file in each mapper. In my driver program, I have added the file to my 
distributed cache using:
       Path p=new 
        DistributedCache.addCacheFile(p.toUri(), conf);

In the configure method of the mapper, I am reading the file from cache using:
            Path[] cacheFiles=DistributedCache.getFileClassPaths(conf);
            BufferedReader joinReader=new BufferedReader(new 

however, the cacheFiles variable has null value in it. 

There is something mentioned on the Yahoo tutorial for hadoop about distributed 
cache which I do not understand:

As a cautionary note: If you use the local JobRunner in   Hadoop (i.e., what 
happens if you call JobClient.runJob()in a program with no or an empty 
hadoop-conf.xmlaccessible),   then no local data directory is created; the 
getLocalCacheFiles()call will return an empty set of   results. Unit test code 
should take this into account."

what does this mean? I am executing my program in pseudo-distributed mode on 
windows using Eclipse.

Any suggestion in this regard is highly valued. 

Thanks  in advance.

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