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From Vinod Kumar Vavilapalli <vino...@apache.org>
Subject Re: Moving to JDK7, JDK8 and new major releases
Date Tue, 24 Jun 2014 22:42:44 GMT
Tx for the new thread Andrew, hopefully it can attract more eyes.

Here's what I am behind - a modified proposal C.
 - Overall I wouldn't think about EOL of JDK7 and/or JDK8 specifically given how long it has
taken for JDK6 life-cycle to end. We should try to focus on JDK7 only for now.
 - As we have seen, a lot (majority?) of orgs on Hadoop have moved beyond JDK6 and are already
running on JDK7. So upgrading to JDK7 is more of a reflection of reality (to quote Steve)
than it in itself being a disruptive change.
 - We should try decoupling the discussion of major releases from JDK upgrades. We have seen
individual libraries getting updated right in the 2.x lines as and when necessary. Given the
new reality of JDK7, I don't see the 'JDK change' as much different from the library upgrades.

We have seen how long it has taken (and still taking) users and organization to move from
Hadoop 1 to Hadoop 2. A Hadoop 3/4 that adds nothing else other than JDK upgrades will be
a big source of confusion for users. A major version update is also seen an opportunity for
devs to break APIs. Unless we have groundbreaking 'features' (like YARN or wire-compatibility
in Hadoop-2) that a majority of users want and that specifically warrant incompatible changes
in our APIs or wire protocols, we are better off separating the major-version update discussion
into ints own.

Irrespective of all this, we should actively get behind better isolation of user classes/jars
from MapReduce classpath. This one's been such a long running concern, it's not funny anymore.


On Jun 24, 2014, at 11:17 AM, Andrew Wang <andrew.wang@cloudera.com> wrote:

> Hi all,
> Forking this thread as requested by Vinod. To help anyone who's catching up
> with this thread, I've written up a wiki page containing what I think are
> the proposals under discussion. I did my very best to make this as
> fact-based and disinterested as possible; I really appreciate the
> constructive discussion we've had so far. If you believe you have a
> proposal pending, please feel free to edit the wiki.
> https://wiki.apache.org/hadoop/MovingToJdk7and8
> I think based on our current compatibility guidelines, Proposal A is the
> most attractive. We're pretty hamstrung by the requirement to keep the
> classpath the same, which would be solved by either OSGI or shading our
> deps (but that's a different discussion).
> Thanks,
> Andrew

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