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From Andrew Wang <andrew.w...@cloudera.com>
Subject Re: Looking to a Hadoop 3 release
Date Tue, 03 Mar 2015 16:03:44 GMT
Hi Junping, thanks for your response,

I view branch-3 as essentially the same size as our recent 2.x releases,
with the exception of incompatible changes like classpath isolation and
JDK8 target version. These, while perhaps not revolutionary, are still
incompatible, and require a major version bump.

I don't see a forking of the community effort, since backports should flow
pretty easily from branch-3 to branch-2 the same way they currently can
flow from branch-2 to branch-2.6. It's just an extra git commit, not like
what we had to deal with in the branch-1 days with a custom backport.

Hopefully that addresses your concerns.

Thanks,
Andrew

On Tue, Mar 3, 2015 at 6:12 AM, Junping Du <jdu@hortonworks.com> wrote:

> Thanks all for good discussions here.
> +1 on supporting Java 8 ASAP. In addition, I agree that we should
> separating this effort with cutting down Hadoop 3.
> IMO, Hadoop is still very cool today, and we should only consider Hadoop 3
> until we have revolutionary feature (like YARN for 2.0) which deserve to
> break fundamental compatibilities. Or it may just cause more distractions
> for community effort.
> Just 2 cents.
>
> Thanks,
>
> Junping
> ________________________________________
> From: Akira AJISAKA <ajisakaa@oss.nttdata.co.jp>
> Sent: Tuesday, March 03, 2015 12:04 PM
> To: common-dev@hadoop.apache.org; mapreduce-dev@hadoop.apache.org;
> hdfs-dev@hadoop.apache.org; yarn-dev@hadoop.apache.org
> Subject: Re: Looking to a Hadoop 3 release
>
> Thanks Andrew for bringing this up.
> +1 mostly looks fine but I'm thinking it's not now to cut branch-3.
>
>  > classpath isolation
>
> IMHO, classpath isolation is a good thing to do.
> We should pay down the technical dept ASAP. I'm willing to help.
>
> I'm thinking we can cut branch-3 and release 3.0 alpha
> after HADOOP-11656 is fixed. That is, I'd like to mark
> this issue as a blocker for 3.0.
> I wonder that even if we cut branch-3 now, trunk and
> branch-3 would be the same for a while. That seems useless.
>
>  > JDK8
>
> As Steve suggested, JDK8 can be in both trunk and branch-2.
> +1 for moving to JDK8 ASAP.
>
>  > maintaining 2.x
>
> For user side, now there is little merit to upgrade to 3.x.
> More important thing is how long 2.x will be maintained.
> Therefore we should consider when to stop backporting
> new features to 2.x, and when to stop maintaining 2.x.
> I'd like to maintain 2.x as long as possible, at least
> one year after 3.x GA release.
>
> * Other issue
>
> What's the current status of HDFS symlink?
> If HADOOP-10019 requires some incompatible changes,
> I'd like to include in 3.x.
>
> Regards,
> Akira
>
> On 3/2/15 15:19, Andrew Wang wrote:
> > Hi devs,
> >
> > It's been a year and a half since 2.x went GA, and I think we're about
> due
> > for a 3.x release.
> > Notably, there are two incompatible changes I'd like to call out, that
> will
> > have a tremendous positive impact for our users.
> >
> > First, classpath isolation being done at HADOOP-11656, which has been a
> > long-standing request from many downstreams and Hadoop users.
> >
> > Second, bumping the source and target JDK version to JDK8 (related to
> > HADOOP-11090), which is important since JDK7 is EOL in April 2015 (two
> > months from now). In the past, we've had issues with our dependencies
> > discontinuing support for old JDKs, so this will future-proof us.
> >
> > Between the two, we'll also have quite an opportunity to clean up and
> > upgrade our dependencies, another common user and developer request.
> >
> > I'd like to propose that we start rolling a series of monthly-ish series
> of
> > 3.0 alpha releases ASAP, with myself volunteering to take on the RM and
> > other cat herding responsibilities. There are already quite a few changes
> > slated for 3.0 besides the above (for instance the shell script rewrite)
> so
> > there's already value in a 3.0 alpha, and the more time we give
> downstreams
> > to integrate, the better.
> >
> > This opens up discussion about inclusion of other changes, but I'm hoping
> > to freeze incompatible changes after maybe two alphas, do a beta (with no
> > further incompat changes allowed), and then finally a 3.x GA. For those
> > keeping track, that means a 3.x GA in about four months.
> >
> > I would also like to stress though that this is not intended to be a big
> > bang release. For instance, it would be great if we could maintain wire
> > compatibility between 2.x and 3.x, so rolling upgrades work. Keeping
> > branch-2 and branch-3 similar also makes backports easier, since we're
> > likely maintaining 2.x for a while yet.
> >
> > Please let me know any comments / concerns related to the above. If
> people
> > are friendly to the idea, I'd like to cut a branch-3 and start working on
> > the first alpha.
> >
> > Best,
> > Andrew
> >
>
>

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