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From "Zheng, Kai" <kai.zh...@intel.com>
Subject RE: Looking to a Hadoop 3 release
Date Wed, 04 Mar 2015 23:50:08 GMT
Might I have some comments for this, just providing my thought. Thanks.

>> If we start now, it might make it out by 2016. If we start now, downstreamers can
start aligning themselves to land versions that suit at about the same time.
Not only for down streamers to align with the long term release, but also for contributors
like me to align with their future effort, maybe.

In addition to the JDK8 support and classpath isolation, might we add more possible candidate
considerations. 
How would you like this one, HADOOP-9797 Pluggable and compatible UGI change ?
https://issues.apache.org/jira/browse/HADOOP-9797

The benefits: 
1) allow multiple login sessions/contexts and authentication methods to be used in the same
Java application/process without conflicts, providing good isolation by getting rid of globals
and statics.
2) allow to pluggable new authentication methods for UGI, in modular, manageable and maintainable
manner.

Another, we would also push the first release of Apache Kerby, preparing for a strong dedicated
and clean Kerberos library in Java for both client and KDC sides, and by leveraging the library,

update Hadoop-MiniKDC and perform more security tests.
https://issues.apache.org/jira/browse/DIRKRB-102

Hope this makes sense. Thanks.

Regards,
Kai

-----Original Message-----
From: saint.ack@gmail.com [mailto:saint.ack@gmail.com] On Behalf Of Stack
Sent: Thursday, March 05, 2015 2:47 AM
To: common-dev@hadoop.apache.org
Cc: mapreduce-dev@hadoop.apache.org; hdfs-dev@hadoop.apache.org; yarn-dev@hadoop.apache.org
Subject: Re: Looking to a Hadoop 3 release

In general +1 on 3.0.0. Its time. If we start now, it might make it out by 2016. If we start
now, downstreamers can start aligning themselves to land versions that suit at about the same
time.

While two big items have been called out as possible incompatible changes, and there is ongoing
discussion as to whether they are or not*, is there any chance of getting a longer list of
big differences between the branches? In particular I'd be interested in improvements that
are 'off' by default that would be better defaulted 'on'.

Thanks,
St.Ack

* Let me note that 'compatible' around these parts is a trampled concept seemingly open to
interpretation with a definition that is other than prevails elsewhere in software. See Allen's
list above, and in our downstream project, the recent HBASE-13149 "HBase server MR tools are
broken on Hadoop 2.5+ Yarn", among others.  Let 3.x be incompatible with 2.x if only so we
can leave behind all current notions of 'compatibility'
and just start over (as per Allen).


On Mon, Mar 2, 2015 at 3:19 PM, Andrew Wang <andrew.wang@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
>
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