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From "Zheng, Kai" <kai.zh...@intel.com>
Subject RE: Looking to a Hadoop 3 release
Date Tue, 03 Mar 2015 00:48:40 GMT
JDK8 support is in the consideration, looks like many issues were reported and resolved already.


-----Original Message-----
From: Andrew Wang [mailto:andrew.wang@cloudera.com] 
Sent: Tuesday, March 03, 2015 7:20 AM
To: common-dev@hadoop.apache.org; mapreduce-dev@hadoop.apache.org; hdfs-dev@hadoop.apache.org;
Subject: Looking to a Hadoop 3 release

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

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.

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