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MapReduce >> mail # dev >> Re: Moving to JDK7, JDK8 and new major releases

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Re: Moving to JDK7, JDK8 and new major releases
After reading this thread and thinking a bit about it, I think it should be
OK such move up to JDK7 in Hadoop 2 for the following reasons:

* Existing Hadoop 2 releases and related projects are running
  on JDK7 in production.
* Commercial vendors of Hadoop have already done lot of
  work to ensure Hadoop on JDK7 works while keeping Hadoop
  on JDK6 working.
* Different from many of the 3rd party libraries used by Hadoop,
  JDK is much stricter on backwards compatibility.

IMPORTANT: I take this as an exception and not as a carte blanche for 3rd
party dependencies and for moving from JDK7 to JDK8 (though it could OK for
the later if we end up in the same state of affairs)

Even for Hadoop 2.5, I think we could do the move:

* Create the Hadoop 2.5 release branch.
* Have one nightly Jenkins job that builds Hadoop 2.5 branch
  with JDK6 to ensure not JDK7 language/API  feature creeps
  out in Hadoop 2.5. Keep this for all Hadoop 2.5.x releases.
* Sanity tests for the Hadoop 2.5.x releases should be done
  with JDK7.
* Apply Steve’s patch to require JDK7 on trunk and branch-2.
* Move all Apache Jenkins jobs to build/test using JDK7.
* Starting from Hadoop 2.6 we support JDK7 language/API

Effectively what we are ensuring that Hadoop 2.5.x builds and test with
JDK6 & JDK7 and that all tests towards the release
are done with JDK7.

Users can proactively upgrade to JDK7 before upgrading to Hadoop 2.5.x, or
if upgrade to Hadoop 2.5.x and they run into any issue because of JDK6
(which it would be quite unlikely) they can reactively upgrade to JDK7.

On Tue, Jun 24, 2014 at 4:22 PM, Andrew Wang <[EMAIL PROTECTED]>