Andrew, Hadoop 3 seems in general like a good idea to me. 1. I did not understand if you propose to release 3.0 instead of 2.7 or in addition? I think 2.7 is needed at least as a stabilization step for the 2.x line.
2. If Hadoop 3 and 2.x are meant to exist together, we run a risk to manifest split-brain behavior again, as we had with hadoop-1, hadoop-2 and other versions. If that somehow beneficial for commercial vendors, which I don't see how, for the community it was proven to be very disruptive. Would be really good to avoid it this time. 3. Could we release Hadoop 3 directly from trunk? With a proper feature freeze in advance. Current trunk is in the best working condition I've seen in years - much better, than when hadoop-2 was coming to life. It could make a good alpha. I believe we can start planning 3.0 from trunk right after 2.7 is out. Thanks, --Konst On Mon, Mar 2, 2015 at 3:19 PM, Andrew Wang <andrew.w...@cloudera.com> 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 >
