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From "Albert Chern" <albert.ch...@gmail.com>
Subject Classes Not Loading Correctly in MapRed 0.7
Date Fri, 13 Oct 2006 02:44:25 GMT

After upgrading from 0.6 to 0.7, we have experienced a strange error
with MapReduce jobs.  Jobs that ran perfectly before now seem to have
trouble finding the classes from our code.  The stack trace is long,
but the errors happen in MapTask.run() when it tries to get the map
output key class from the JobConf, which is probably the first time
any of our classes are loaded.  Then it fails with a

The strange thing is, the error does not occur on all of the machines
in the cluster.  As far as we can tell, the Hadoop installation and
configuration are the same across the machines.  Downgrading to 0.6
fixes the problem.  Has anyone experienced something similar, or have
any idea what could be causing this problem?  Something incorrectly
configured, maybe?


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