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From Andrew Purtell <apurt...@apache.org>
Subject Re: [DISCUSSION] Merge Backup / Restore - Branch HBASE-7912
Date Thu, 08 Sep 2016 16:21:09 GMT
Vlad,

I apologize for using the term 'half-baked' in a way that could seem a
description of HBASE-7912. I meant that as a general hypothetical.

On Wed, Sep 7, 2016 at 9:36 AM, Vladimir Rodionov <vladrodionov@gmail.com>
wrote:

> >> I'm not sure that "There is already lots of half-baked code in the
> branch,
> so what's the harm in adding more?"
>
> I meant - not production - ready yet. This is 2.0 development branch and,
> hence many features are in works,
> not being tested well etc. I do not consider backup as half baked feature -
> it has passed our internal QA and has very good doc, which we will provide
> to Apache shortly.
>
> -Vlad
>
> On Wed, Sep 7, 2016 at 9:13 AM, Andrew Purtell <apurtell@apache.org>
> wrote:
>
> > We shouldn't admit half baked changes that won't be finished. However in
> > this case the crew working on this feature are long timers and less
> likely
> > than just about anyone to leave something in a half baked state. Of
> course
> > there is no guarantee how anything will turn out, but I am willing to
> take
> > a little on faith if they feel their best path forward now is to merge to
> > trunk. I only wish I had bandwidth to have done some real kicking of the
> > tires by now. Maybe this week.
> >
> > (Yes, I'm using some of that time for this email :-) but I type fast.)
> >
> > That said, I would like to agitate for making 2.0 more real and spend
> some
> > time on it now that I'm winding down with 0.98. I think that means
> > branching for 2.0 real soon now and even evicting things from 2.0 branch
> > that aren't finished or stable, leaving them only once again in the
> master
> > branch. Or, maybe just evicting them. Let's take it case by case.
> >
> > I think this feature can come in relatively safely. As added insurance,
> > let's admit the possibility it could be reverted on the 2.0 branch if
> folks
> > working on stabilizing 2.0 decide to evict it because it is unfinished or
> > unstable, because that certainly can happen. I would expect if talk like
> > that starts, we'd get help finishing or stabilizing what's under
> discussion
> > for revert. Or, we'd have a revert. Either way the outcome is acceptable.
> >
> >
> > On Wed, Sep 7, 2016 at 8:56 AM, Dima Spivak <dimaspivak@apache.org>
> wrote:
> >
> > > I'm not sure that "There is already lots of half-baked code in the
> > branch,
> > > so what's the harm in adding more?" is a good code commit philosophy
> for
> > a
> > > fault-tolerant distributed data store. ;)
> > >
> > > More seriously, a lack of test coverage for existing features shouldn't
> > be
> > > used as justification for introducing new features with the same
> > > shortcomings. Ultimately, it's the end user who will feel the pain, so
> > > shouldn't we do everything we can to mitigate that?
> > >
> > > -Dima
> > >
> > > On Wed, Sep 7, 2016 at 8:46 AM, Vladimir Rodionov <
> > vladrodionov@gmail.com>
> > > wrote:
> > >
> > > > Sean,
> > > >
> > > > * have docs
> > > >
> > > > Agree. We have a doc and backup is the most documented feature :), we
> > > will
> > > > release it shortly to Apache.
> > > >
> > > > * have sunny-day correctness tests
> > > >
> > > > Feature has  close to 60 test cases, which run for approx 30 min. We
> > can
> > > > add more, if community do not mind :)
> > > >
> > > > * have correctness-in-face-of-failure tests
> > > >
> > > > Any examples of these tests in existing features? In works, we have a
> > > clear
> > > > understanding of what should be done by the time of 2.0 release.
> > > > That is very close goal for us, to verify IT monkey for existing
> code.
> > > >
> > > > * don't rely on things outside of HBase for normal operation (okay
> for
> > > > advanced operation)
> > > >
> > > > We do not.
> > > >
> > > > Enormous time has been spent already on the development and testing
> the
> > > > feature, it has passed our internal tests and many rounds of code
> > reviews
> > > > by HBase committers. We do not mind if someone from HBase community
> > > > (outside of HW) will review the code, but it will probably takes
> > forever
> > > to
> > > > wait for volunteer?, the feature is quite large (1MB+ cumulative
> patch)
> > > >
> > > > 2.0 branch is full of half baked features, most of them are in active
> > > > development, therefore I am not following you here, Sean? Why
> > HBASE-7912
> > > is
> > > > not good enough yet to be integrated into 2.0 branch?
> > > >
> > > > -Vlad
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > On Wed, Sep 7, 2016 at 8:23 AM, Sean Busbey <busbey@apache.org>
> wrote:
> > > >
> > > > > On Tue, Sep 6, 2016 at 10:36 PM, Josh Elser <josh.elser@gmail.com>
> > > > wrote:
> > > > > > So, the answer to Sean's original question is "as robust as
> > snapshots
> > > > > > presently are"? (independence of backup/restore failure tolerance
> > > from
> > > > > > snapshot failure tolerance)
> > > > > >
> > > > > > Is this just a question WRT context of the change, or is it
means
> > > for a
> > > > > veto
> > > > > > from you, Sean? Just trying to make sure I'm following along
> > > > adequately.
> > > > > >
> > > > > >
> > > > >
> > > > > I'd say ATM I'm -0, bordering on -1 but not for reasons I can
> > > articulate
> > > > > well.
> > > > >
> > > > > Here's an attempt.
> > > > >
> > > > > We've been trying to move, as a community, towards minimizing risk
> to
> > > > > downstream folks by getting "complete enough for use" gates in
> place
> > > > > before we introduce new features. This was spurred by a some
> features
> > > > > getting in half-baked and never making it to "can really use"
> status
> > > > > (I'm thinking of distributed log replay and the zk-less assignment
> > > > > stuff, I don't recall if there was more).
> > > > >
> > > > > The gates, generally, included things like:
> > > > >
> > > > > * have docs
> > > > > * have sunny-day correctness tests
> > > > > * have correctness-in-face-of-failure tests
> > > > > * don't rely on things outside of HBase for normal operation (okay
> > for
> > > > > advanced operation)
> > > > >
> > > > > As an example, we kept the MOB work off in a branch and out of
> master
> > > > > until it could pass these criteria. The big exemption we've had to
> > > > > this was the hbase-spark integration, where we all agreed it could
> > > > > land in master because it was very well isolated (the slide away
> from
> > > > > including docs as a first-class part of building up that
> integration
> > > > > has led me to doubt the wisdom of this decision).
> > > > >
> > > > > We've also been treating inclusion in a "probably will be released
> to
> > > > > downstream" branches as a higher bar, requiring
> > > > >
> > > > > * don't moderately impact performance when the feature isn't in use
> > > > > * don't severely impact performance when the feature is in use
> > > > > * either default-to-on or show enough demand to believe a
> non-trivial
> > > > > number of folks will turn the feature on
> > > > >
> > > > > The above has kept MOB and hbase-spark integration out of branch-1,
> > > > > presumably while they've "gotten more stable" in master from the
> odd
> > > > > vendor inclusion.
> > > > >
> > > > > Are we going to have a 2.0 release before the end of the year?
> We're
> > > > > coming up on 1.5 years since the release of version 1.0; seems like
> > > > > it's about time, though I haven't seen any concrete plans this
> year.
> > > > > Presuming we are going to have one by the end of the year, it
> seems a
> > > > > bit close to still be adding in "features that need maturing" on
> the
> > > > > branch.
> > > > >
> > > > > The lack of a concrete plan for 2.0 keeps me from considering these
> > > > > things blocker at the moment. But I know first hand how much
> trouble
> > > > > folks have had with other features that have gone into downstream
> > > > > facing releases without robustness checks (i.e. replication), and
> I'm
> > > > > concerned about what we're setting up if 2.0 goes out with this
> > > > > feature in its current state.
> > > > >
> > > >
> > >
> >
> >
> >
> > --
> > Best regards,
> >
> >    - Andy
> >
> > Problems worthy of attack prove their worth by hitting back. - Piet Hein
> > (via Tom White)
> >
>



-- 
Best regards,

   - Andy

Problems worthy of attack prove their worth by hitting back. - Piet Hein
(via Tom White)

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