Home | About | Sematext search-lucene.com search-hadoop.com
 Search Hadoop and all its subprojects:

Switch to Threaded View
Accumulo >> mail # dev >> Hadoop 2 compatibility issues

Copy link to this message
Re: Hadoop 2 compatibility issues
I think it's interesting that Option 4 seems to be most preferred...
because it's the *only* option that is explicitly advised against by
the Maven developers (from the information I've read). I can see its
appeal, but I really don't think that we should introduce an explicit
problem for users (that applies to users using even the Hadoop version
we directly build against... not just those using Hadoop 2... I don't
know if that point was clear), to only partially support a version of
Hadoop that is still alpha and has never had a stable release.

BTW, Option 4 was how I had have achieved a solution for
ACCUMULO-1402, but am reluctant to apply that patch, with this issue
outstanding, as it may exacerbate the problem.

Another implication for Option 4 (the current "solution") is for
1.6.0, with the planned accumulo-maven-plugin... because it means that
the accumulo-maven-plugin will need to be configured like this:
   ... all the required hadoop 1 dependencies to make the plugin work,
even though this version only works against hadoop 1 anyway...

Christopher L Tubbs II
On Tue, May 14, 2013 at 5:42 PM, Christopher <[EMAIL PROTECTED]> wrote:
> I think Option 2 is the best solution for "waiting until we have the
> time to solve the problem correctly", as it ensures that transitive
> dependencies work for the stable version of Hadoop, and using Hadoop2
> is a very simple documentation issue for how to apply the patch and
> rebuild. Option 4 doesn't wait... it explicitly introduces a problem
> for users.
> Option 1 is how I'm tentatively thinking about fixing it properly in 1.6.0.
> --
> Christopher L Tubbs II
> http://gravatar.com/ctubbsii
> On Tue, May 14, 2013 at 4:56 PM, John Vines <[EMAIL PROTECTED]> wrote:
>> I'm an advocate of option 4. You say that it's ignoring the problem,
>> whereas I think it's waiting until we have the time to solve the problem
>> correctly. Your reasoning for this is for standardizing for maven
>> conventions, but the other options, while more 'correct' from a maven
>> standpoint or a larger headache for our user base and ourselves. In either
>> case, we're going to be breaking some sort of convention, and while it's
>> not good, we should be doing the one that's less bad for US. The important
>> thing here, now, is that the poms work and we should go with the method
>> that leaves the work minimal for our end users to utilize them.
>> I do agree that 1. is the correct option in the long run. More
>> specifically, I think it boils down to having a single module compatibility
>> layer, which is how hbase deals with this issue. But like you said, we
>> don't have the time to engineer a proper solution. So let sleeping dogs lie
>> and we can revamp the whole system for 1.5.1 or 1.6.0 when we have the
>> cycles to do it right.
>> On Tue, May 14, 2013 at 4:40 PM, Christopher <[EMAIL PROTECTED]> wrote:
>>> So, I've run into a problem with ACCUMULO-1402 that requires a larger
>>> discussion about how Accumulo 1.5.0 should support Hadoop2.
>>> The problem is basically that profiles should not contain
>>> dependencies, because profiles don't get activated transitively. A
>>> slide deck by the Maven developers point this out as a bad practice...
>>> yet it's a practice we rely on for our current implementation of
>>> Hadoop2 support
>>> (http://www.slideshare.net/aheritier/geneva-jug-30th-march-2010-maven
>>> slide 80).
>>> What this means is that even if we go through the work of publishing
>>> binary artifacts compiled against Hadoop2, neither our Hadoop1
>>> binaries or our Hadoop2 binaries will be able to transitively resolve
>>> any dependencies defined in profiles. This has significant
>>> implications to user code that depends on Accumulo Maven artifacts.
>>> Every user will essentially have to explicitly add Hadoop dependencies