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Subject: Re: [DISCUSS] Looking to a 2.8.0 release
From: Allen Wittenauer <aw@altiscale.com>
In-Reply-To: <0C22896E-D77B-4DE4-99A2-9D81E150779C@hortonworks.com>
Date: Wed, 11 Nov 2015 12:43:31 -0800
Cc: Hadoop Common <common-dev@hadoop.apache.org>,
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To: hdfs-dev@hadoop.apache.org


> On Nov 11, 2015, at 12:13 PM, Vinod Vavilapalli =
<vinodkv@hortonworks.com> wrote:
>=20
>    =E2=80=94 HDFS-6200 Create a separate jar for hdfs-client: =
Compatible improvement - no dimension of alpha/betaness here.

	IMO: this feels like a massive break in backwards compatibility. =
Anyone who is looking for specific methods in specific jars are going to =
have a bad time. Also, it seems as though every week a new issue crops =
up that is related to this change.  Is Slider still having problems with =
it?  The reasoning =E2=80=9Cwell, the pom sets the dependencies so =
it=E2=80=99s ok=E2=80=9D feels like an *extremely weak* reason this =
wasn=E2=80=99t marked incompatible=E2=80=94 it basically makes the =
assumption that everyone recompiles for every minor release.

>    =E2=80=94 Compatibility tools to catch backwards, forwards =
compatibility issues at patch submission, release times. Some of it is =
captured at YARN-3292. This also involves resurrecting jdiff =
(HADOOP-11776/YARN-3426/MAPREDUCE-6310) and/or investing in new tools.

	There has been talk in the past about adding Java ACC support to =
Yetus.

> Thoughts?

	I=E2=80=99d rather see efforts on 3.x than another disastrous =
2.x release.  The track record is not good.  At least a new major will =
signify that danger looms ahead.  We=E2=80=99re already treating 2.x =
minor releases as effectively major (see the list of incompatible JIRAs) =
so what different does it make if we do 2.x vs. 3.x anyway?

>=20
> Thanks
> +Vinod
> PS:As you may have noted above, this time around, I want to do =
something that we=E2=80=99ve always wanted to do, but never explicitly =
did. I=E2=80=99m calling out readiness of each feature as they stand =
today so we can inform our users better of what they can start relying =
on in production clusters.

	=E2=80=A6 except some of these changes are so deep reaching that =
even if you don=E2=80=99t use the feature, you=E2=80=99re still impacted =
by it ...