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From István Tóth <st...@cloudera.com.INVALID>
Subject Re: Moving Phoenix master to Hbase 2.2
Date Mon, 13 Jan 2020 07:25:49 GMT
Hi!

(Sorry for not replying earlier, I'll need to revisit my mail filters)

I do have a half-baked patch with the lightweight isolation in modules case.

In its current form it's more ugly than complex, but some ugliness is  a
small price to pay for not having to maintain multiple branches. (And it
can be beutified later)

I will complete it, and make the PR for that as time permits.

The tephra solution handles the version differences during run (startup)
time, my current solution is compile-time.

Istvan




On Fri, Dec 20, 2019 at 11:05 AM larsh@apache.org <larsh@apache.org> wrote:

>  Yep that.
> For the record... I do not think this is simple. But it is possible.
>
>     On Thursday, December 19, 2019, 8:37:37 PM GMT+1, Andrew Purtell <
> apurtell@apache.org> wrote:
>
>  I can't answer for Lars but whenever version incompatibilities come up
> usually only a handful of files are impacted. In the last round, the
> Phoenix access controller, a related file in the same directory, and the
> RPC scheduler. If you cloned these into separate version specific maven
> modules case by case as needed at each round the differences are fairly
> small. On the other hand if you take a principled approach and abstract all
> the things, it will be a huge effort and nobody realistically will want to
> take it on.
>
> On Thu, Dec 19, 2019 at 11:34 AM Geoffrey Jacoby <gjacoby@gmail.com>
> wrote:
>
> > Lars,
> >
> > I'm curious why you say the differences are easily isolated -- many of
> the
> > core classes of Phoenix either directly inherit HBase classes or
> implement
> > HBase interfaces, and those can vary between minor versions. (See my
> above
> > example of a new coprocessor hook on BaseRegionObserver.)
> >
> > Geoffrey
> >
> > On Thu, Dec 19, 2019 at 10:54 AM larsh@apache.org <larsh@apache.org>
> > wrote:
> >
> > >  Yep. The differences are pretty minimal - provided they can be
> isolated
> > > easily.
> > > Tephra might be a pretty good model. It supports various versions of
> > HBase
> > > in a single branch and has similar issues as Phoenix (coprocessors,
> etc).
> > > -- Lars
> > >    On Thursday, December 19, 2019, 7:07:51 PM GMT+1, Josh Elser <
> > > elserj@apache.org> wrote:
> > >
> > >  To clarify, you think that compat modules are better than that
> > > separate-branches model in 4.x?
> > >
> > > On 12/18/19 11:29 AM, larsh@apache.org wrote:
> > > > This is really hard to follow.
> > > >
> > > > I think we should do the same with HBase dependencies in Phoenix that
> > > HBase does with Hadoop dependencies.
> > > >
> > > > That is:  We could have a maven module with the specific HBase
> version
> > > dependent code.
> > > > Btw. Tephra does the same... A module for HBase version specific
> code.
> > > > -- Lars
> > > >
> > > >      On Tuesday, December 17, 2019, 10:00:31 AM GMT+1, Istvan Toth <
> > > stoty@apache.org> wrote:
> > > >
> > > >  What do you think about tying the minor releases to Hbase minor
> > releases
> > > > (not necessarily one-to-one)
> > > >
> > > > for example (provided 5.1 is 2020H1)
> > > >
> > > > 5.0.0 -> HB 2.0
> > > > 5.1.0 -> HB 2.2.2 (and whatever 2.1 is API compatible with it)
> > > > 5.1.x -> HB 2.2.x (treat as maintenance branch, no major new
> features)
> > > > 5.2.0 -> HB 2.3.0 (if released by that time)
> > > > 5.2.x -> HB 2.3.x (treat as maintenance branch, no major new
> features)
> > > > 5.3.0 -> HB 2.3.x (if there is no new major/minor Hbase release)
> > > > master -> latest released HBase version
> > > >
> > > > Alternatively, we could stick with the same HBase version for patch
> > > > releases that we used for the first minor release.
> > > >
> > > > This would limit the number of branches that we have to maintain in
> > > > parallel, while providing maintenance branches for older releases,
> and
> > > > timely-ish Phoenix releases.
> > > >
> > > > The drawback is that users of old HBase versions won't get the latest
> > > > features, on the other hand they can expect more polish.
> > > >
> > > > Istvan
> > > >
> > > > On Thu, Dec 12, 2019 at 8:05 PM Geoffrey Jacoby <gjacoby@apache.org>
> > > wrote:
> > > >
> > > >> Since HBase 2.0 is EOM'ed, I'm +1 for not worrying about 2.0.x
> > > >> compatibility with the 5.x branch going forward.
> > > >>
> > > >> Given how coupled Phoenix is to the implementation details of HBase
> > > though,
> > > >> I'm not sure trying to abstract those away to keep one Phoenix
> branch
> > > per
> > > >> HBase major version is practical, however. At the least, it would
be
> > > really
> > > >> complex.
> > > >>
> > > >> For example, in the new year I plan to return to working on the
> change
> > > data
> > > >> capture and Phoenix-level replication features, both of which depend
> > on
> > > >> WALKey interface changes and a new RegionObserver coprocessor hook
> > > >> introduced in HBASE-22622 and HBASE-22623. This was released in
> HBase
> > > 1.5
> > > >> and will be in the forthcoming HBase 2.3. While the HBase community
> is
> > > >> discussing EOMing 1.3 right now, and maybe 1.4 will go in the medium
> > > term,
> > > >> I don't see all pre-2.3 branch-2's getting deprecated anytime soon.
> > > >>
> > > >> So there will be at least two significant features that can only
> exist
> > > in
> > > >> some but not all of our 4.x and 5.x branches.
> > > >>
> > > >> Geoffrey
> > > >>
> > > >> On Thu, Dec 12, 2019 at 8:21 AM Josh Elser <elserj@apache.org>
> wrote:
> > > >>
> > > >>> As much as possible, I'd like to avoid us getting into another
> > > situation
> > > >>> with 5.x where we have multiple branches. My hope was/is that
we
> can
> > > >>> keep one Phoenix5 branch that works against an acceptable set
of
> > HBase
> > > >>> branches.
> > > >>>
> > > >>> To me, that acceptable set of HBase branches is _a_ 2.1 and 2.2
> > > release.
> > > >>> I don't think we need to support all 2.1.x or 2.2.x, nor do I
think
> > we
> > > >>> need to keep trying to maintain 2.0.x as it's already end of
> support
> > by
> > > >>> the HBase community.
> > > >>>
> > > >>> Thanks for updating your PR. I'll add this to my review queue.
> > > >>>
> > > >>> On 12/12/19 1:52 AM, Istvan Toth wrote:
> > > >>>> Hi!
> > > >>>>
> > > >>>> I'd like to start a conversation about supporting HBase 2.2.
in
> the
> > > >>>> master branch.
> > > >>>>
> > > >>>> https://issues.apache.org/jira/browse/PHOENIX-5268 has a slightly
> > out
> > > >> of
> > > >>>> date, but functional PR for HBase 2.2 support on master. (Please
> > > review
> > > >>>> and comment if you have the time, I'll try to update the PR
in the
> > > next
> > > >>>> few days)
> > > >>>>
> > > >>>> The reason that it is not a straightforward decision to merge
it
> is
> > > >> that
> > > >>>> applying that patch breaks compatibility with HBase 2.0.1,
the
> > current
> > > >>>> base.
> > > >>>>
> > > >>>> I can see the following outcomes:
> > > >>>>
> > > >>>> - Do nothing
> > > >>>> - Move master to HBase 2.2.2
> > > >>>> - Fork master to Hbase-2.0 and Hbase-2.2 branches
> > > >>>> - Build time compatibility modules
> > > >>>> - Run time compatibility modules
> > > >>>> - Something that I haven't thought of
> > > >>>>
> > > >>>>
> > > >>>> Doing nothing is obviously not a long term solution, as the
> current
> > > >>>> master doesn't work with any of the currently supported HBase
> > > branches,
> > > >>>> but we may postpone the inevitable.
> > > >>>>
> > > >>>> Simply moving master to HBase 2.2 is the most attractive solution
> > from
> > > >> a
> > > >>>> pure developer POV, but there may be other considerations.
> > > >>>>
> > > >>>> Having multiple masters for 2.0 and 2.2 is simple from a code
> > > >>>> perspective, but maintaining two branches is a non-trivial
amount
> of
> > > >>>> additional work. (See the 4.x situation)
> > > >>>>
> > > >>>> Moving the HBase version dependent stuff into a separate module,
> and
> > > >>>> choosing at build time is not pretty from a code POV, but
saves us
> > the
> > > >>>> hassle of maintaining multiple branches, while maintaining
> > > >> compatibility
> > > >>>> with multiple  HBase versions, and can handle future API changes
> as
> > > >> well
> > > >>>> from a single branch. Doing something like this could have
saved
> us
> > > the
> > > >>>> effort of maintaining three separate 4.x branches.
> > > >>>>
> > > >>>> I feel that since Phoenix is closely timed to HBase, and requires
> > > >>>> cluster-wide HBase configuration to work anyway, handling
the
> > > different
> > > >>>> HBase versions from the same binary/JAR is not worth the effort.
> > > >>>>
> > > >>>> Please share your thoughts!
> > > >>>>
> > > >>>> regards
> > > >>>> Istvan
> > > >>>>
> > > >>>
> > > >>
> > > >
> > > >
> > >
> >
>
>
> --
> Best regards,
> Andrew
>
> Words like orphans lost among the crosstalk, meaning torn from truth's
> decrepit hands
>   - A23, Crosstalk
>



-- 
*István Tóth* | Sr. Software Engineer
t. (36) 70 283-1788
stoty@cloudera.com <https://www.cloudera.com>
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