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From Arun C Murthy <...@hortonworks.com>
Subject Re: [DISCUSS] stabilizing Hadoop releases wrt. downstream
Date Fri, 01 Mar 2013 18:58:39 GMT
I feel this is being blown out of proportion.

Integration is high on the list of *every* release. In future, if anyone or bigtop wants to
help, running integration tests on a hadoop RC and providing feedback would be very welcome.
I'm pretty sure I will stop an RC if it means it breaks and Oozie or HBase or Pig or Hive
and re-spin it. For e.g. see recent efforts to do a 2.0.4-alpha.

With hadoop-2.0.3-alpha we discovered 3 *bugs* - making it sound like we intentionally disregard
integation issues is very harsh.

Please also see other thread where we discussed stabilizing APIS, protocols etc. for the next
'beta' release.


On Feb 26, 2013, at 5:43 PM, Roman Shaposhnik wrote:

> Hi!
> for the past couple of releases of Hadoop 2.X code line the issue
> of integration between Hadoop and its downstream projects has
> become quite a thorny issue. The poster child here is Oozie, where
> every release of Hadoop 2.X seems to be breaking the compatibility
> in various unpredictable ways. At times other components (such
> as HBase for example) also seem to be affected.
> Now, to be extremely clear -- I'm NOT talking about the *latest* version
> of Oozie working with the *latest* version of Hadoop, instead
> my observations come from running previous *stable*  releases
> of Bigtop on top of Hadoop 2.X RCs.
> As many of you know Apache Bigtop aims at providing a single
> platform for integration of Hadoop and Hadoop ecosystem projects.
> As such we're uniquely positioned to track compatibility between
> different Hadoop releases with regards to the downstream components
> (things like Oozie, Pig, Hive, Mahout, etc.). Every single single RC
> we've been pretty diligent at trying to provide integration-level feedback
> on the quality of the upcoming release,  but it seems that our efforts
> don't quite suffice in Hadoop 2.X stabilizing.
> Of course, one could argue that while Hadoop 2.X code line was
> designated 'alpha' expecting much in the way of perfect integration
> and compatibility was NOT what the Hadoop community was
> focusing on. I can appreciate that view, but what I'm interested in
> is the future of Hadoop 2.X not its past. Hence, here's my question
> to all of you as a Hadoop community at large:
> Do you guys think that the project have reached a point where integration
> and compatibility issues should be prioritized really high on the list
> of things that make or break each future release?
> The good news, is that Bigtop's charter is in big part *exactly* about
> providing you with this kind of feedback. We can easily tell you when
> Hadoop behavior, with regard to downstream components, changes
> between a previous stable release and the new RC (or even branch/trunk).
> What we can NOT do is submit patches for all the issues. We are simply
> too small a project and we need your help with that.
> I truly believe that we owe it to the downstream projects, and in the
> second half of this email I will try to convince you of that.
> We all know that integration projects are impossible to pull off
> unless there's a general consensus between all of the projects involved
> that they indeed need to work with each other. You can NOT force
> that notion, but you can always try to influence. This relationship
> goes both ways.
> Consider a question in front of the downstream communities
> of  whether or not to adopt Hadoop 2.X as the basis. To answer
> that question each downstream project has to be reasonably
> sure that their concerns will NOT fall on deaf ears and that
> Hadoop developers are, essentially, 'ready' for them to pick
> up Hadoop 2.X. I would argue that so far the Hadoop community
> had gone out of its way to signal that 2.X codeline is NOT
> ready for the downstream.
> I would argue that moving forward this is a really unfortunate
> situation that may end up undermining the long term success
> of Hadoop 2.X if we don't start addressing the problem. Think
> about it -- 90% of unit tests that run downstream on Apache
> infrastructure are still exercising Hadoop 1.X underneath.
> In fact, if you were to forcefully make, lets say, HBase's
> unit tests run on top of Hadoop 2.X quite a few of them
> are going to fail. Hadoop community is, in effect, cutting
> itself off from the biggest source of feedback -- its downstream
> users. This in turn:
>   * leaves Hadoop project in a perpetual state of broken
>     windows syndrome.
>   * leaves Apache Hadoop 2.X releases in a state considerably
>     inferior to the releases *including* Apache Hadoop done by the
>     vendors. The users have no choice but to alight themselves
>     with vendor offerings if they wish to utilize latest Hadoop functionality.
>     The artifact that is know as Apache Hadoop 2.X stopped being
>     a viable choice thus fracturing the user community and reducing
>     the benefits of a commonly deployed codebase.
>    * leaves downstream projects of Hadoop  in a jaded state where
>      they legitimately get very discouraged and frustrated and eventually
>      give up thinking that -- well, we work with one release of Hadoop
>      (the stable one Hadoop 1.X) and we shall wait for the Hadoop
>      community to get their act together.
> In my view (shared by quite a few members of the Apache Bigtop) we
> can definitely do better than this if we all agree that the proposed
> first 'beta' release of Hadoop 2.0.4 is the right time for it to happen.
> It is about time Hadoop 2.X community wins back all those end users
> and downstream projects that got left behind during the alpha
> stabilization phase.
> Thanks,
> Roman.

Arun C. Murthy
Hortonworks Inc.

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