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From Pat Ferrel <>
Subject Re: ClassNotFoundException while using RecommenderJob
Date Fri, 16 Mar 2012 22:28:46 GMT
Thanks, [1] is a very good reference for ClassNotFoundException.

As you say in [2] the mahout script does not accept hadoop job 
parameters in all cases although I hope it does in the future, 
especially where a parameter to the job is a classname (seq2sparse for 

What I had to do was copy my custom analyzer jar into $HADOOP_HOME/lib 
on the master node. Evidently a symlink does not work, it appears you 
have to copy each jar you want to the directory.

Then don't forget to stop and start hadoop because as [1] says it 
packages the libs at startup.

On 3/16/12 7:12 AM, Ioan Eugen Stan wrote:
> Pe 15.03.2012 15:51, Pat Ferrel a scris:
>> Can you elaborate on how to set these classpaths?
>> The job takes a classpath param, (from mahout --help)
>> -libjars <paths> comma separated jar files to include in
>> the classpath.
>> is the needed code bundled with the job or does the path need to be
>> available to hadoop/mahout on all nodes? Also is this the only thing
>> that affects the classpath to any code outside the jar file?
>> On 3/15/12 5:33 AM, Ioan Eugen Stan wrote:
>>> Also, if you submit a job there are two class paths that you must be
>>> aware of:
>>> - the one that starts the job submitting app
>>> - the one that will be available to the job on each node
> Hi Pat,
> To set up your main app class-path use HADOOP_CLASS_PATH env var. For 
> the Job class-path it's best explained here [1], although, from my 
> experience -libjars did not work as advertised. It's hadoop version 
> dependant probably but I may be wrong. Test and see for yourself.
> Also see my post on common-user about this issue [2]. Search for 
> ClassNotFoundException: libjars .
> [1] 
> [2]
> Hope this helps,

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