hadoop-common-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Andrew Wang <andrew.w...@cloudera.com>
Subject Re: Hadoop - Major releases
Date Mon, 09 Mar 2015 22:34:28 GMT
Hi Mayank,

Note that Hadoop 3 does not mean the end of updates for Hadoop 2.x, which
will keep supporting JDK7 for a while yet. Someone on the original thread
also proposed keeping Hadoop 3 JDK7-source compatible to make backports to
2.x easier. I support this.

Note also that the jump from Hadoop 1 to Hadoop 2 (which is what I assume
was your previous migration) is a far, far more impactful change than what
is being proposed for Hadoop 3. Hadoop 3 will look basically like a 2.x
release except for the JDK8 bump and classpath isolation. The intent is to
otherwise maintain wire and API compatibility.

Overall your timeline sounds like it fits the schedule I proposed. If we
release a 3.0 GA this year, it means you can upgrade to a baked 3.1 or 3.2
next year. Seems like a sound upgrade procedure for a large cluster.

Best,
Andrew

On Mon, Mar 9, 2015 at 2:24 PM, Mayank Bansal <mabansal@gmail.com> wrote:

> Hi Guys,
>
> From my prospective @ ebay we are not going to upgrade to JDK 8 any time
> soon we just upgraded to 7 and not want to move further at least this year
> so I will request you guys not to drop the support for JDK 7 as that would
> be very crucial for us to move forward.
>
> We also just completed our Hadoop 2 migration for all clusters this year
> which we started earlier last year, so I don't think we can do again major
> upgrades this year. Stabilizing the major releases takes lots of effort and
> time, I think Hadoop 3.x makes sense at least for us next year.
>
> Thanks,
>
> Mayank
>
> On Mon, Mar 9, 2015 at 12:29 AM, Arun Murthy <acm@hortonworks.com> wrote:
>
> > Over the last few days, we have had lots of discussions that have
> > intertwined several major themes:
> >
> >
> >
> > # When/why do we make major Hadoop releases?
> >
> > # When/how do we move to major JDK versions?
> >
> > # To a lesser extent, we have debated another theme: what do we do about
> > trunk?
> >
> >
> >
> > For now, let's park JDK & trunk to treat them in a separate thread(s).
> >
> >
> >
> > For a while now, I've had a couple of lampposts in my head which I used
> > for guidance - apologize for not sharing this broadly prior to this
> > discussion, maybe putting it out here will help - certainly hope so.
> >
> >
> >
> >
> >
> > Major Releases
> >
> >
> >
> > Hadoop continues to benefit tremendously by the investment in stability,
> > validation etc. put in by its *anchor* users: Yahoo, Facebook, Twitter,
> > eBay, LinkedIn etc.
> >
> >
> >
> > A historical perspective...
> >
> >
> >
> > In it's lifetime, Apache Hadoop went from monthly to quarterly releases
> > because, as Hadoop became more and more of a production system (starting
> > with hadoop-0.16 and more so with hadoop 0.18), users could not absorb
> the
> > torrid pace of change.
> >
> >
> >
> > IMHO, we didn't go far enough in addressing the competing pressures of
> > stability v/s rapid innovation.  We paid for it by losing one of our
> anchor
> > users - Facebook - around the time of hadoop-0.19 - they just forked.
> >
> >
> >
> > Around the same time, Yahoo hit the same problem (I know, I lived through
> > it painfully) and got stuck with hadoop-0.20 for a *very* long time and
> > forked to add Security rather than deal with the next major release
> > (hadoop-0.21). Later on, Facebook did the same, and, unfortunately for
> the
> > community, is stuck - probably forever - on their fork of hadoop-0.20.
> >
> >
> >
> > Overall, these were dark days for the community: every anchor user was on
> > their own fork, and it took a toll on the project.
> >
> >
> >
> > Recently, thankfully for Hadoop, we have had a period of relative
> > stability with hadoop-1.x and hadoop-2.x. Even so, there were close
> shaves:
> > Yahoo was on hadoop-0.23 for a *very* long time - in fact, they are only
> > just now finishing their migration to hadoop-2.x.
> >
> >
> >
> > I think the major lessons here are the obvious ones:
> >
> >
> >
> > # Compatibility matters
> >
> > # Maintaining ?multiple major releases, in parallel, is a big problem -
> it
> > leads to an unproductive, and risky, split in community investment along
> > different lines.
> >
> >
> >
> >
> >
> > Looking Ahead
> >
> >
> >
> > Given the above, here are some thoughts for looking ahead:
> >
> >
> >
> > # Be very conservative about major releases - a major benefit is required
> > (features) for the cost. Let's not compel our anchor users like Yahoo,
> > Twitter, eBay, and LinkedIn to invest in previous releases rather than
> the
> > latest one. Let's hear more from them - and let's be very accommodating
> to
> > them - for they play a key role in keeping Hadoop healthy & stable.
> >
> >
> >
> > # Be conservative about dropping support for JDKs. In particular, let's
> > hear from our anchor users on their plans for adoption jdk-1.8. LinkedIn
> > has already moved to jdk-1.8, which is great for the validation , but
> let's
> > wait for the rest of our anchor users to move before we drop jdk-1.7. We
> > did the same thing with jdk-1.6 - waited for them to move before we drop
> > support for jdk-1.7.
> >
> >
> >
> > Overall, I'd love to hear more from Twitter, Yahoo, eBay and other anchor
> > users on their plans for jdk-1.8 specifically, and on their overall
> > appetite for hadoop-3.  Let's not finalize our plans for moving forward
> > until this input has been considered.
> >
> >
> >
> > Thoughts?
> >
> >
> > thanks,
> > Arun
> >
> >
> >
> > Unfortunate that it's necessary disclaimers:
> >
> > # Before people point out vendor affiliations to lend unnecessary color
> to
> > my opinions, let me state that hadoop-2 v/s hadoop-3 is a non-issue for
> us.
> > For major HDP versions the key is, just, compatibility?... e.g. we ship
> > major, but compatible, community releases such as hive-0.13/hive-0.14 in
> > HDP-2.x/HDP-2.x+1 etc.
> >
> > # Also, release management is a similar non-issue - we have already had
> > several individuals step up in hadoop-2.x line. Expect more of the same
> > from folks like Andrew, Karthik, Vinod, Steve etc.
> >
>
>
>
> --
> Thanks and Regards,
> Mayank
> Cell: 408-718-9370
>

Mime
  • Unnamed multipart/alternative (inline, None, 0 bytes)
View raw message