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 developers http://lordjoesoftware.blogspot.com/ -- Steven M. Lewis PhD 4221 105th Ave Ne Kirkland, WA 98033 206-384-1340 (cell) Institute for Systems Biology Seattle WA
