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Hadoop >> mail # user >> Caution using Hadoop 0.21


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Re: Caution using Hadoop 0.21
On Sat, Nov 13, 2010 at 4:33 PM, Shi Yu <[EMAIL PROTECTED]> 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.