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From Eric Yang <>
Subject Re: Chukwa can't find Demux class
Date Wed, 28 Apr 2010 17:23:16 GMT
Hi Kirk,

Is the ownership of the jar file setup correctly as the user that runs
demux?  You may find more information by looking at running mapper task or
reducer task, and try to find out the task attempt shell script.  Make sure
the files are downloaded correctly from distributed cache, and referenced in
the locally generated jar file.  Hope this helps.


On 4/28/10 9:37 AM, "Kirk True" <> wrote:

> Hi guys,
> I have a custom Demux that I need to run to process my input, but I'm getting
> ClassNotFoundException when running in Hadoop. This is with the released 0.4.0
> build.
> I've done the following:
> 1. I put my Demux class in the correct package
> (org.apache.hadoop.chukwa.extraction.demux.processor.mapper)
> 2. I've added the JAR containing the Demux implementation to HDFS at
> /chuka/demux 
> 3. I've added an alias to it in chukwa-demux-conf.xml
> The map/reduce job is picking up on the fact that I have a custom Demux and is
> trying to load it, but I get a ClassNotFoundException. The HDFS-based URL to
> the JAR is showing up in the job configuration in Hadoop, which is another
> evidence that Chukwa and Hadoop know where the JAR lives and that it's part of
> the Chukwa-initiated job.
> My Demux is very simple. I've stripped it down to a System.out.println with
> dependencies on no other classes/JARs other than Chukwa, Hadoop, and the core
> JDK. I've double-checked that my JAR is being built up correctly. I'm
> completely flummoxed as to what I'm doing wrong.
> Any ideas what I'm missing? What other information can I provide?
> Thanks!
> Kirk

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