On Thu, Sep 10, 2015 at 4:17 PM, Britton Smith <brittonsmith@gmail.com> wrote:

Hi Andrew,

Have we continued to have problems with PRs being issued to the wrong head now that Bitbucket tags the heads with bookmarks?  If so, then maybe that's the end, but I was under the impression that that had taken care of this.

I don't think it has come up since that hapenned, but we haven't been in a situation where the "experimental" bookmark was the tip of the yt branch for more than a day or two.

 

As far as allowing development to take place in a single dev head, I am worried about ending up in the situation where many new features in there are ready to go and some are not.  If development has continued over multiple PRs on different features, will it still be possible to pick out only the features that are ready?  If so, then I guess that's that, but if not, then I am very wary of this.

In practice how would this problem work? Right now we have an experimental bookmark including both unstructured mesh support and the volume rendering refactor. Since unstructured mesh support depends on the VR refactor, we can't release that it without also releasing the VR refactor. In principle we could release the VR refactor without unstructured mesh support, but I think we all agree that 3.3 should probably include both features.

I think merging a new feature into a single-headed yt branch implicitly means that that the feature will be "done" in time for the next major release. If we have more than one work-in-progress features due for the next major release, then the release is blocked on all of them. As a community we need to be careful to not merge in features if we're not prepared to block the release on them until they are done.

 

Maybe as a way to move this discussion forward, since there seems to be two main perspectives, is there any way at all for us to compromise? I'm not sure there is, since some of us think it's ok to have work-in-progress features in the dev branch while they're still not fully baked, while others strongly object. Maybe we could have a discussion about what level of "doneness" a new feature needs to have before it can be merged in? Right now the level of acceptable "doneness" is quite high, and maybe it can be relaxed a bit while still keeping everyone happy.

Britton

On Thu, Sep 10, 2015 at 4:59 PM, Andrew Myers <atmyers2@gmail.com> wrote:

I just want to chime in to say I agree with Nathan and Matt re: allowing more active development on the yt branch. Ideally, I think there should be two branches (stable and yt) with one head each, with the yt branch being the "development" version of the code. Most users would be on the stable branch, and more active users / developers would be on the development branch. Having multiple heads / bookmarks on the yt branch makes for a more complicated development process (as evidenced by the fact that none of us can remember how it works in this very email chain ;) ), which can be discouraging for new developers. Since creating the experimental bookmark for the scene refactor, we've already had PRs accidently made and merged into the wrong head, and it's created more work for Kacper in keeping the CI working smoothly. 

I appreciate the concerns about release deadlines creating pressure to release under-documented and under-tested code. However, and as others have stated, with Nathan's backport script, we can now do bugfix releases as often as needed, which removes some (most? all?) of that pressure. 

Additionally, I agree that in practice, most of the serious testing of new features is going to be done after the code gets merged, and the community of yt developers / active users who use the development version of the code get their hands on it. Doing that merge sooner rather than later will result in an overall faster timeline to stable code.

To be clear, I think Britton's proposal is a definite improvement over the "forks of forks" model, but I think an even simpler development process with only one head on the main yt branch would be more productive in the long run.

On Thu, Sep 10, 2015 at 1:23 PM, Matthew Turk <matthewturk@gmail.com> wrote:

Hi Britton,

I was going to reply, broadly in support of everything you suggested, until I saw the other emails.  It looks like I missed my opportunity.

In general, I would like to see more experimental development in the main yt repo; I think with the backporting script, as you suggest, we now have a good reason for people to use "stable" instead of the main development branch.

So I guess "multiple heads" even with multiple bookmarks is off the table now, if I read the rest of the thread correctly?  If so, can we figure out a way to allow experimental stuff into "yt" and then move most folks onto "stable"?

On Thu, Sep 10, 2015 at 1:52 PM, Britton Smith <brittonsmith@gmail.com> wrote:

Hi everyone,

I had some ideas for improving the yt development process that I

wanted to run by everyone.  This can be discussed further at our

upcoming team meeting and if people are in favor, I will issue a pull

request to the relevant YTEP.

STATEMENT OF PROBLEM

Currently, development proceeds roughly as follows.  The two main

active branches within the central yt repository are yt and stable.

The tip of stable is the latest release and the yt branch is the de

facto "development version" of the code.  Until recently, we have not

been very good at regularly scheduled minor releases and so the stable

branch sits for quite some time with many bugs that are fixed within

the development branch.  This effectively makes stable unusable and

pushes most users to the yt branch.

When new features are developed, pull requests are issued to the

single head of the yt branch.  Because this is the version most people

are actually using, the current policy is to not allow PR with new

functionality to be accepted until they are 100% ready (full

functionality, tests, docs, etc).  As we have already seen, this makes

collaborative development very cumbersome, as it requires people to

create forks of the fork from which the PR originates.  They then must

issue PRs to that fork after which time the original PR is updated.

The current volume render refactor is the perfect example of this.

PROPOSED SOLUTION

Before I lay out the proposed solution, I want to list a number of

recent developments that I think will make this possible:

1. Nathan's new script for backporting changes now keeps stable and yt

   synced on bugfixes.

2. We have returned to doing minor releases containing only bugfixes,

   thanks again to Nathan's hard work.  This and point 1 means that

   users are once again safe to be on stable, and now should be there

   most of the time.

3. Bitbucket now supports bookmarks, meaning that PRs can be issued to

   specific bookmarks instead of to branches or heads named only by the

   changeset hash.

4. The weekly PR triage hangouts are making it easier to process PRs

   and also providing a place to strategize getting larger PRs

   accepted.  Thanks to Hilary for keeping this going.

With the above in mind, I propose the following:

1. Create a "development" bookmark to sit at the tip of the yt

   branch.  All PRs containing relatively small new features are

   issued to this.  The requirements for acceptance remain the same:

   PRs accepted to "development" must contain all intended

   functionality and be fully documented.  This allows the

   "development" bookmark to be defined explicitly as everything that

   will be included in the next major release.

2. Large new features should have a corresponding YTEP that has been

   accepted.  After the YTEP has been accepted, a PR should be issued

   to the yt branch.  After some initial discussion, this PR is pulled

   into the main yt repo with a bookmark named after the feature.

   Once this has happened, developers can now issue new PRs

   specifically to this bookmark.  This is effectively what we have

   now with the volume render work in the "experimental" bookmark,

   only we would rename the bookmark to something like "vr-refactor".

   As with PRs issued directly to "development", only after the new

   feature is 100% ready shall it be merged into the "development"

   bookmark.

3. We continue to make use of the PR triage hangouts to establish when

   large features are ready to be merged.

I believe this will have the following benefits:

1. Large, new features can be developed collaboratively without the

   need for forks of forks of forks.

2. New, underdevelopment features are more accessible to the larger

   community by simply updating to named bookmarks from the main repo

   (no need for "just pull these changes from my fork").

3. The "development" branch is preserved as a place only for

   ready-to-be-released features (i.e., polished and documented).

All told, this is really just a small tweak on our current process.

Please comment with any thoughts, or even a +/-1 if your feelings can

be summed up thusly.

Britton

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