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From lars hofhansl <la...@apache.org>
Subject Re: [DISCUSS] More new feature backports to 0.94.
Date Sat, 02 Mar 2013 03:22:57 GMT
That is only if we do not backport stabilizing "features". There is an "opportunity cost" to
be paid if we take a too rigorous approach too.

Take for example table-lock (which prompted this discussion). With that in place we can do
safe online schema upgrade (that won't fail and leave the table in an undefined state when
a concurrent split happens), it also allows for online merge.

Now, is that a destabilizing "feature", or will it make HBase more stable and hence an "improvement"?
Depends on viewpoint, doesn't it?

-- Lars



________________________________
 From: Jean-Marc Spaggiari <jean-marc@spaggiari.org>
To: dev@hbase.apache.org 
Sent: Friday, March 1, 2013 7:12 PM
Subject: Re: [DISCUSS] More new feature backports to 0.94.
 
@Lars: No, not any concern about anything already backported. Just a
preference to #2 because it seems to make things more stable and
easier to manage. New feature = new release. Given new sub-releases
are for fixes and improvements, but not new features. Also, if we
backport a feature in one or many previous releases, we will have to
backport also all the fixes each time there will be an issue. So we
will have more maintenant work on previous releases.

2013/3/1 Enis Söztutar <enis.soz@gmail.com>:
> I think the current way of risk vs rewards analysis is working well. We
> will just continue doing that on a case by case basis, discussing the
> implications on individual issues.
>
>
>
> On Fri, Mar 1, 2013 at 6:46 PM, Lars Hofhansl <lhofhansl@yahoo.com> wrote:
>
>> BTW are you concerned about any specific back port we did in the past? So
>> far we have not seen any destabilization in any of the 0.94 releases.
>>
>> Jean-Marc Spaggiari <jean-marc@spaggiari.org> wrote:
>>
>> >Hi Lars, #2, does it mean you will stop back-porting the new features
>> >when it will become a "long-term" release? If so, I'm for option #2...
>> >
>> >JM
>> >
>> >In your option
>> >2013/3/1 Enis Söztutar <enis.soz@gmail.com>:
>> >> Thanks Lars, I think it is a good listing of the options we have.
>> >>
>> >> I'll be +1 for #1 and #2, with #1 being a preference.
>> >>
>> >> Enis
>> >>
>> >>
>> >> On Fri, Mar 1, 2013 at 6:10 PM, lars hofhansl <larsh@apache.org> wrote:
>> >>
>> >>> So it seems that until we have a stable 0.96 (maybe 0.96.1 or 0.96.2)
>> we
>> >>> have three options:
>> >>> 1. Backport new features to 0.94 as we see fit as long as we do not
>> >>> destabilize 0.94.
>> >>> 2. Declare a certain point release (0.94.6 looks like a good
>> candidate) as
>> >>> a "long term", create an 0.94.6 branch (in addition to the usual 0.94.6
>> >>> tag) and than create 0.94.6.x fix only releases. I would volunteer to
>> >>> maintain a 0.94.6 branch in addition to the 0.94 branch.
>> >>> 3. Categorically do not backport new features into 0.94 and defer to
>> 0.95.
>> >>>
>> >>> I'd be +1 on option #1 and #2, and -1 on option #3.
>> >>>
>> >>> -- Lars
>> >>>
>> >>>
>> >>>
>> >>> ________________________________
>> >>>  From: Jonathan Hsieh <jon@cloudera.com>
>> >>> To: dev@hbase.apache.org; lars hofhansl <larsh@apache.org>
>> >>> Sent: Friday, March 1, 2013 3:11 PM
>> >>> Subject: Re: [DISCUSS] More new feature backports to 0.94.
>> >>>
>> >>> I think we are basically agreeing -- my primary concern is bringing
new
>> >>> features in vital paths introduces more risk, I'd rather not backport
>> major
>> >>> new features unless we achieve a higher level of assurance through
>> system
>> >>> and basic fault injection testing.
>> >>>
>> >>> For the three current examples -- snapshots, zk table locks, online
>> merge
>> >>> -- I actually would prefer not including any in apache 0.94.  Of the
>> bunch,
>> >>> I feel the table locks are the most risky since it affects vital paths
>> a
>> >>> user must use,  where as snapshots and online merge are features that
a
>> >>> user could choose to use but does not necessarily have to use.  I'll
>> voice
>> >>> my concerns, reason for concerns, and justifications on the individual
>> >>> jiras.
>> >>>
>> >>> I do feel that new features being in a dev/preview release like 0.95
>> aligns
>> >>> well and doesn't create situations where different versions have
>> different
>> >>> feature sets.  New features should be introduced and hardened in a
>> >>> dev/preview version, and the turn into the production ready versions
>> after
>> >>> they've been proven out a bit.
>> >>>
>> >>> Jon.
>> >>>
>> >>> On Fri, Mar 1, 2013 at 11:00 AM, lars hofhansl <larsh@apache.org>
>> wrote:
>> >>>
>> >>> > This is an open source project, as long as there is a volunteer
to
>> >>> > backport a patch I see no problem with doing this.
>> >>> > The only thing we as the community should ensure is that it must
be
>> >>> > demonstrated that the patch does not destabilize the 0.94 code
base;
>> that
>> >>> > has to be done on a case by case basis.
>> >>> >
>> >>> >
>> >>> > Also, there is no stable release of HBase other than 0.94 (0.95
is
>> not
>> >>> > stable, and we specifically state that it should not be used in
>> >>> production).
>> >>> >
>> >>> > -- Lars
>> >>> >
>> >>> >
>> >>> >
>> >>> > ________________________________
>> >>> >  From: Jonathan Hsieh <jon@cloudera.com>
>> >>> > To: dev@hbase.apache.org
>> >>> > Sent: Friday, March 1, 2013 8:31 AM
>> >>> > Subject: [DISCUSS] More new feature backports to 0.94.
>> >>> >
>> >>> > I was thinking more about HBASE-7360 (backport snapshots to 0.94)
and
>> >>> also
>> >>> > saw HBASE-7965 which suggests porting some major-ish features (table
>> >>> locks,
>> >>> > online merge) in to the apache 0.94 line.   We should chat about
>> what we
>> >>> > want to do about new features and bringing them into stable versions
>> >>> (0.94
>> >>> > today) and in general criteria we use for future versions.
>> >>> >
>> >>> > This is similar to the snapshots backport discussion and earlier
>> backport
>> >>> > discussions.  Here's my understanding of  high level points we
>> basically
>> >>> > agree upon.
>> >>> > * Backporting new features to the previous major version incurs
more
>> cost
>> >>> > when developing new features,  pushes back efforts on making the
>> trunk
>> >>> > versions and reduces incentive to move to newer versions.
>> >>> > * Backporting new features to earlier versions (0.9x.0, 0.9x.1)
is
>> >>> > reasonable since they are generally less stable.
>> >>> > * Backporting new features to later version (0.9x.5, 0.9x.6) is
less
>> >>> > reasonable --  (ex: a 0.94.6, or 0.94.7 should only include robust
>> >>> > features).
>> >>> > * Backporting orthogonal features (snapshots) seems less risky
than
>> core
>> >>> > changing features
>> >>> > * An except: If multiple distributions declare intent to backport,
it
>> >>> makes
>> >>> > sense to backport a feature. (snapshots for example).
>> >>> >
>> >>> > Some new circumstances and discussion topics:
>> >>> > * We now have a dev branch (0.95) with looser compat requirements
>> that we
>> >>> > could more readily release with dev/preview versions.  Shouldn't
this
>> >>> > reduce the need to backport features to the apache stable branches?
>> >>> Would
>> >>> > releases of these releases "replace" the 0.x.0 or 0.x.1 releases?
>> >>> > * For major features in later versions we should raise the bar
on the
>> >>> > amount of testing probably be more explicit about what testing
is
>> done
>> >>> > (unit tests not suffcient, system testing stories/resports a
>> >>> requirement).
>> >>> > Any other suggestions?
>> >>> >
>> >>> > Jon.
>> >>> >
>> >>> > --
>> >>> > // Jonathan Hsieh (shay)
>> >>> > // Software Engineer, Cloudera
>> >>> > // jon@cloudera.com
>> >>> >
>> >>>
>> >>>
>> >>>
>> >>> --
>> >>> // Jonathan Hsieh (shay)
>> >>> // Software Engineer, Cloudera
>> >>> // jon@cloudera.com
>> >>>
>>
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