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From Andrew Purtell <andrew.purt...@gmail.com>
Subject Re: [DISCUSS] Criteria for including MOB feature backport in branch-1
Date Thu, 03 Mar 2016 22:15:26 GMT
In addition to Stack's points those of us running HBase in production will need assurance in
the form of data collected from a plausible test environment that the MOB backport does not
affect function, stability, or performance for anyone who doesn't want it. Furthermore some
affirmative demonstration of its benefit in a community reproducible way continues to be overdue
on master and in my view mandatory for branch-1. 

> On Mar 3, 2016, at 1:01 PM, Stack <stack@duboce.net> wrote:
> 
>> On Thu, Mar 3, 2016 at 9:02 AM, Ted Yu <yuzhihong@gmail.com> wrote:
>> 
>> Hi,
>> As requested by Sean Busbey, I am starting a new thread w.r.t. backporting
>> MOB feature to branch-1.
> This is to solicit discussion on the criteria for including MOB feature
>> backport in branch-1.
>> 
>> I can think of the following:
>> 1. whether there is customer interest
>> 
>> There is.
>> See Jonathan's response here: http://search-hadoop.com/m/YGbbDSqxD1PYXK62
> You should probably mention that a note requesting if there was interest
> got no response here on the public lists. This would seem to imply no
> interest by the community?
> 
> Jon's note is pregnant but opaque on the details of these 'supported'
> deploys. He is in a bit of an awkward spot unable to share detail on
> someone else's deploy.
> 
> Would be good to see more interest than Jon's note as evidence of interest
> I'd say.
> 
> You know of any? Even if they could be described in outline and hopefully
> more than one instance and that MOB makes sense for this deploy. And they
> need it now in a branch-1?
> 
> Which version of hbase are we talking of backporting too? 1.3? 1.4?
> 
> 
> 
>> 2. whether unit test stability can be maintained in branch-1
>> 
>> Inclusion of the backport should keep unit tests (both existing and new) in
>> branch-1 green.
>> Preliminary test runs showed that MOB / snapshot related tests consistently
>> pass.
>> 
>> 
>> https://issues.apache.org/jira/browse/HBASE-15370?focusedCommentId=15176094&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-15176094
> 
> 
> Hopefully we are aiming for more than just 'test stability'. Some large
> community users have placed big bets on branch-1 being stable at scale;
> this is the stability we should be precious of -- not just 'test stability'.
> 
> Besides, I see failures in your listing. MOB is pervasive. Why is it not
> responsible for the mentioned test failures? (And "... passes on my local
> machine... " doesn't cut it; builds.apache.org is our public CI where
> community comes together on state of branch and master, not some devs
> laptop).
> 
> Branch-1 builds have been generally stable after large investment fixing,
> tuning and pruning tests. Master branch had been rendered stable but seems
> to be rotting again though it is the most important of our builds given it
> can catch the bad stuff before the commits make it in. During the campaign
> to stabilize Master, MOB tests failed often. I see MOB failures in master
> patch build from time to time still (I've been lax of late but our flakies
> list contains a few mentionds, see HBASE-15012). They go unaddressed
> (though, to be fair, Jingcheng, the original author, addressed a few
> failures early on when asked). Just this morning I note:
> https://builds.apache.org/view/H-L/view/HBase/job/PreCommit-HBASE-Build/818/testReport/junit/org.apache.hadoop.hbase.mob.mapreduce/TestMobSweepMapper/org_apache_hadoop_hbase_mob_mapreduce_TestMobSweepMapper/
> 
> 
> (Suggestion: MOB seems to be better in master branch of late -- Matteo and
> Heng work I believe (or just my disabling of broke tests) -- so a review
> and report of master and patch builds looking for MOB failures and fixing
> any found would help address the above concern. Another way to build
> confidence in a patched branch-1 would be doing the branch suggested up in
> the backport issue and then running builds on apache for a period. Or
> better, copy what was done by Jon et al. to build confidence; run
> long-running ITBLLs on a cluster w/ MOB set with obnoxious configs and post
> evidence it all holds up).
> 
> 
>> Comments are welcome
>> 
>> <https://issues.apache.org/jira/browse/HBASE-15370#>
> 
> 
> Is MOB an 'owned' feature. The MOB original author is mostly absent (for
> instance, no participation in these conversations and no general follow-up
> on test failures). As has been said before many times, features need to be
> owned. Writing the code is just one part of owning a feature. Features that
> are not owned become a burden on the community to maintain. We have enough
> of this latter type of feature already.
> 
> (Jingcheng did show up in the last day though with HBASE-15381"Implement a
> distributed MOB compaction by procedure" which looks like a pretty
> important issue and begs the question, is MOB finished? And if not,
> shouldn't we wait till its done before we backport?)
> 
> Finally, MOB backport should be done by someone who is familiar with MOB. I
> see no evidence of your expertise in MOB other than an odd review nor even
> that you've run it in other than a unit test mode. Not to mention that the
> way you go about the backport, dumping an 800k blob of unattributed code
> into the issue for review in HBASE-15370, does not bode well for our
> continued stability.
> 
> St.Ack

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