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From Steve Lewis <lordjoe2...@gmail.com>
Subject Re: Caution using Hadoop 0.21
Date Sun, 14 Nov 2010 19:04:44 GMT
I did not say I never saw an API change - what I said and stand by is that I
have not
seen a major public class change in a way that would break older code.
 Adding a few methods to
a class is OK. Adding new classes and packages are OK. Adding methods to a
public interface is very bad -
although Java did this with different versions of JDBC. But changing an
important public class from a
class to an interface - a move guaranteed to break code of anyone
subclassing that class is pretty much unheard of

On Sat, Nov 13, 2010 at 8:53 PM, Edward Capriolo <edlinuxguru@gmail.com>wrote:

> On Sat, Nov 13, 2010 at 4:33 PM, Shi Yu <shiyu@uchicago.edu> wrote:
> > I agree with Steve. That's why I am still using 0.19.2 in my production.
> >
> > Shi
> >
> > On 2010-11-13 12:36, Steve Lewis wrote:
> >>
> >> 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/
> >>
> >>
> >
> >
> >
>
> At times we have been frustrated by rapidly changing API's
>
> # 23 August, 2010: release 0.21.0 available
> # 26 February, 2010: release 0.20.2 available
> # 14 September, 2009: release 0.20.1 available
> # 23 July, 2009: release 0.19.2 available
> # 22 April, 2009: release 0.20.0 available
>
> By the standard major/minor/revision scheme 0.20.X->0.21.X is a minor
> release. However since hadoop has never had a major release you might
> consider 0.20->0.21 to be a "major" release.
>
> In any case, are you saying that in 15 years of coding you have never
> seen an API change between minor releases? I think that is quite
> common. It was also more then a year between 0.20.X and 0.21.X.  Again
> common to expect a change in that time frame.
>



-- 
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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