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From Steve Lewis <lordjoe2...@gmail.com>
Subject Caution using Hadoop 0.21
Date Sat, 13 Nov 2010 18:36:08 GMT
Our group made a very poorly considered decision to build out cluster using
Hadoop 0.21
We discovered that a number of programs written and running properly under
0.20.2 did not work
under 0.21

The first issue is that Mapper.Context and Reducer.Context and many of their
superclasses were
converted from concrete classes to interfaces. This change, and I have never
in 15 years of programming Java seen so major
a change to well known public classes is guaranteed to break any code which
subclasses these objects.

While it is a far better decision to make these classes interface, the
manner of the change and the fact that it is poorly
documented shows extraordinary poor judgement on the part of the Hadoop


Steven M. Lewis PhD
4221 105th Ave Ne
Kirkland, WA 98033
206-384-1340 (cell)
Institute for Systems Biology
Seattle WA

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