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 <maban...@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 <a...@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 >
