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Re: What is required for LTS releases? (was: [PROPOSAL] Prepare Beam 2.8.0 release)

On Wed, Oct 10, 2018 at 2:56 AM Robert Bradshaw <robertwb@xxxxxxxxxx> wrote:
On Wed, Oct 10, 2018 at 9:37 AM Ismaël Mejía <iemejia@xxxxxxxxx> wrote:
The simplest thing we can do is just to pin all the deps of the LTS
and not move them in any maintenance release if not a strong reason to
do so.

The next subject is to make maintainers aware of which release will be
the LTS in advance so they decide what to do with the dependencies
versions. In my previous mail I mentioned all the possible cases that
can happen with dependencies and it is clear that one unified policy
won’t satisfy every one. So better let the maintainers (who can also
ask for user feedback in the ML) to decide about  versions before the

Alexey’s question is still a really important issue, and has been so
far ignored. What happens with the ‘Experimental’ APIs in the LTS.
Options are:

(1) We keep consistent with Experimental which means that they are
still not guarantees (note that this does not mean that they will be
broken arbitrarily).
(2) We are consistent with the LTS approach which makes them ‘non
experimental’ for the LTS so we will guarantee the functionality/API

I personally have conflicted opinions I would like to favor (1) but
this is not consistent with the whole idea of LTS so probably (2) is

Yeah, I think (2) is the only viable option. 

I think important thing here is that future releases on a  LTS branch will be patch (bugfix) releases so I don't think we can/should do API/functionality changes (even if the change is experimental and/or backwards compatible).

I think same goes for dependency changes. If the change is to fix a known bug we can do that in a patch release but if it's to add more functionality probably that should come in a new minor release instead of a patch release. 

This is why I think we should be bit careful about "rushed" changes to major functionalities of Beam going into LTS releases. Just my 2 cents.

Finally I also worry about Tim’s remarks on performance and quality,
even if some of these things effectively can be fixed in a subsequent
LTS release. Users will probably prefer a LTS to start with Beam and
if the performance/quality of the LTS, this can hurt perception of the

Yes, for this reason I think it's important to consider what goes into an LTS as well as what happens after. Almost by definition, using an LTS is choosing stability over cutting edge features. I'd rather major feature X goes in after LTS, and lives in a couple of releases gaining fixes and improvements before being released as part of the next LTS, than quickly making it into an LTS while brand new (both due to the time period before we refine it, and the extra work of porting refinements back). 

Or maybe LTS-users are unlikely to pick up a x.y.0 release anyway, waiting for at least x.y.1? 

Come to think of it, do we even have to designate releases at LTS at the time of release? Perhaps we could instead just keep with our normal release cadence, and periodically choose one of them as LTS once we've confirmed its stability out in the wild and start backporting to it. (I can think of several cons with this approach as well, e.g. generally it's easier to backport bugfixes at the time a bugfix is done in master rather than swapping in context at a later date, but just thought I'd throw it out there.)

On Wed, Oct 10, 2018 at 4:53 AM Kenneth Knowles <kenn@xxxxxxxxxx> wrote:
> I've seen two mentions that "rushing" is contrary to the goals of LTS. But I wouldn't worry about this. The fact is there is almost nothing you can do to stabilize *prior* to cutting the LTS branch. Stability comes from the branch being long-lived and having multiple releases.
> (I think this is pretty much my version of what JB is saying)
> What a conservative user will do if 2.8.x is declared LTS is to start using the 2.8.x branch after it has had a couple bugfix releases. I don't think it is useful or possible to try for an "extra stable" 2.x.0.
> The arguments about supporting the most widely used versions of runner backends apply regardless of LTS. We should support them if we have the resources to do so.
> Kenn
> On Tue, Oct 9, 2018 at 4:57 PM Ahmet Altay <altay@xxxxxxxxxx> wrote:
>> On Fri, Oct 5, 2018 at 4:38 AM, Jean-Baptiste Onofré <jb@xxxxxxxxxxxx> wrote:
>>> Hi,
>>> I think we have to remember what it's a LTS. A LTS is clearly a branch
>>> that we guarantee to have fixes on it for a long period of time.
>>> It doesn't mean that LTS == unique release. We can do a bunch of
>>> releases on a LTS branch, the only constraint is to avoid to introduce
>>> breaking changes.
>> I agree with this perspective. Thank you for sharing this. However the other commenters also had a good point. Requiring users to upgrade their runner version maybe incompatible with the goals of an LTS branch. Ideally the fixes here should be very minimal and targeted.
>>> So, IMHO, the key part is not release, it's branch.
>>> The first thing to decide is the branch.
>>> Instead of talking about 2.8.0 or 2.9.0, I would prepare a 2.8.x LTS
>>> branch. It's a branch where we will cherry-pick some important fixes in
>>> the future and where we will cut release. It's the approach I use in
>>> other Apache projects (especially Karaf) and it works fine.
>> JB, does Karaf has a documented process that we can re-use? If not could you explain a bit more?
>> Is the proposal here to prepare 2.8.x LTS branch and make a 2.8.0 release out of that?
>>> Just my $0.01
>>> Regards
>>> JB
>>> On 05/10/2018 12:14, Robert Bradshaw wrote:
>>> > On Fri, Oct 5, 2018 at 3:59 AM Chamikara Jayalath <chamikara@xxxxxxxxxx
>>> > <mailto:chamikara@xxxxxxxxxx>> wrote:
>>> >
>>> >
>>> >     On Thu, Oct 4, 2018 at 9:39 AM Ahmet Altay <altay@xxxxxxxxxx
>>> >     <mailto:altay@xxxxxxxxxx>> wrote:
>>> >
>>> >         I agree that LTS releases require more thought. Thank you for
>>> >         raising these questions. What other open questions do we have
>>> >         related LTS releases?
>>> >
>>> >         One way to do this would be to add them to a particular tracking
>>> >         list (e.g. 2.9.0 blocking list) that way we would be ready for
>>> >         an LTS release ahead of time.
>>> >
>>> >         Related to dependencies, I agree with Thomas. If we block on
>>> >         waiting for dependencies, we may end up taking a long time
>>> >         before making any LTS release. And the reality of Beam releases
>>> >         right now is that there are no supported releases today that and
>>> >         in the long term that might hurt user trust. In my opinion, we
>>> >         need to fix that sooner rather than later.
>>> >
>>> >
>>> >     Agree on the idea of focussing on stability instead of feature set
>>> >     when it comes to LTS releases. Based on the previous discussion on
>>> >     this [1] looks like the intended audience is enterprise customers
>>> >     that would like to maintain a stable environment and that usually
>>> >     have a long testing cycle before deploying a new version. Seems
>>> >     like, rushing in features  or dependency upgrades for an LTS release
>>> >     will be counterintuitive for such use cases.
>>> >
>>> >     On the other hand, I think a part of Ismaël point was that all major
>>> >     features of Beam (Spark Runner, Flink Runner, Kafka IO, etc ..)
>>> >     should be supportable for the duration of the time Beam LTS release
>>> >     is supported (1 year based on [1]). If a major dependency is
>>> >     expected to become unsupported within an year, it makes sense to
>>> >     upgrade that before the LTS release. I suggest we do this at least
>>> >     one release before the planned LTS release (so 2.9.0 if we want to
>>> >     make 2.10.0 a LTS release) so that we have all major
>>> >     dependency/feature updates battle tested before committing to them.
>>> >
>>> >
>>> > Dependencies are a significant concern. What happens if one of our
>>> > dependencies has no version they're going to support for a year hence?
>>> > It could happen that there's never a time when all our dependencies will
>>> > be supported for at least a year as of any given date. And rushing to
>>> > get the "latest" version of a dependency in is often contrary to the
>>> > goals of an LTS. (Better to have those depend on the battle-hardened
>>> > versions.)
>>> >
>>> > The long-term goal is probably to avoid pinning specific versions as
>>> > much as possible. E.g. if we worked with Flink 1.5 or 1.6 (whichever the
>>> > user provided), and considered backporting support for 1.7 when it came
>>> > out, we'd be in much better shape here. How feasible this is depends on
>>> > how backwards-compatible the dependency is.
>>> >
>>> > On the other hand, forcing a user to upgrade a (user-visible, which in
>>> > particular includes runners) dependency seems contrary to the goals of
>>> > an LTS. Even if that dependency becomes unsupported.
>>> >
>>> >
>>> --
>>> Jean-Baptiste Onofré
>>> jbonofre@xxxxxxxxxx
>>> http://blog.nanthrax.net
>>> Talend - http://www.talend.com