On Mon, Jan 8, 2018 at 11:28 PM, Aaron T. Myers <a...@apache.org> wrote:

> Thanks a lot for the response, Larry. Comments inline.
>
> On Mon, Jan 8, 2018 at 6:44 PM, larry mccay <lmc...@apache.org> wrote:
>
>> Question...
>>
>> Can this be addressed in some way during or before upgrade that allows it
>> to only affect new installs?
>> Even a config based workaround prior to upgrade might make this a change
>> less disruptive.
>>
>> If part of the upgrade process includes a step (maybe even a script) to
>> set the NN RPC port explicitly beforehand then it would allow existing
>> deployments and related clients to remain whole - otherwise it will uptake
>> the new default port.
>>
>
> Perhaps something like this could be done, but I think there are downsides
> to anything like this. For example, I'm sure there are plenty of
> applications written on top of Hadoop that have tests which hard-code the
> port number. Nothing we do in a setup script will help here. If we don't
> change the default port back to what it was, these tests will likely all
> have to be updated.
>
>

I may not have made my point clear enough.
What I meant to say is to fix the default port but direct folks to
explicitly set the port they are using in a deployment (the current
default) so that it doesn't change out from under them - unless they are
fine with it changing.


>
>> Meta note: we shouldn't be so pedantic about policy that we can't back
>> out something that is considered a bug or even mistake.
>>
>
> This is my bigger point. Rigidly adhering to the compat guidelines in this
> instance helps almost no one, while hurting many folks.
>
> We basically made a mistake when we decided to change the default NN port
> with little upside, even between major versions. We discovered this very
> quickly, and we have an opportunity to fix it now and in so doing likely
> disrupt very, very few users and downstream applications. If we don't
> change it, we'll be causing difficulty for our users, downstream
> developers, and ourselves, potentially for years.
>

Agreed.


>
> Best,
> Aaron
>

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