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Linus On Branching Practices
rocket22 writes "Not long ago Linus Torvalds made some comments about issues the kernel maintainers were facing while applying the 'feature branch' pattern. They are using Git (which is very strong with branching and merging) but still need to take care of the branching basics to avoid ending up with unstable branches due to unstable starting points. While most likely your team doesn't face the same issues that kernel development does, and even if you're using a different DVCS like Mercurial, it's worth taking a look at the description of the problem and the clear solution to be followed in order to avoid repeating the same mistakes. The same basics can be applied to every version control system with good merge tracking, so let's avoid religious wars and focus on the technical details."
I think that the development process should be selected to match the particular project and the stage it is in. There is no perfect process that applies to every project, or even to one project forever. A team of 4 in a single room working on a demo for a new product idea will have very different requirements from a team of 20 working in two locations on an improved version of a product that is already in production...
There are two conflicting goals: to avoid breaking the main branch (trunk) and to get changes out to the other developers soon. A broken main branch wastes the time of other developers on the project. But integrating changes late has its own inefficiencies: Problems in the modifications will only be raised after the work is done. It is more likely for one set of modifications to conflict with another set if both are being developed in parallel for a longer time. Other developers might have to wait for a full set of changes to arrive while they only need a subset, or they might start merging the subset from each other's development branches, creating a confusing mix of versions.
Committing directly into trunk can be acceptable and even desirable depending on the project. It depends on how likely commits are to break the code: How many developers are there? How many mistakes do they make? (a combination of experience and carefulness) Is there decent test coverage before committing? How fragile is the code base; are there many unexpected side effects? And it depends on how much damage a broken main branch does: How long does it typically take to find and fix a problem? How modular is the code base: will a bug in one part be a nuisance to developers working on another part? And it also depends on how much there is to gain from early merging: Is the project in the start-up phase where it is likely that other developers are waiting for new core functionality, or is the code base mature and are most changes done on the edges of the program? Are all design decisions made before code is written or are developers doing design and implementation work at the same time?
I go in the reverse.
Trunk is dev, branches are stable. We haven't had much trouble with this set up at all.
I'm god, but it's a bit of a drag really...
We did this where I worked previously too. It was also the MO for the artists building the artwork for the game.
Your trunk is the "Main line", a boiling pot of all the changes and can change on a minute by minute bases right near crunch time; This is good because you fail early if your change is not compatible with other changes instead of at the end of the day or whatever. This is very important for artwork.
The last known good build is tagged/labelled (or branch if you prefer) and was generated by an auto build process that ran tests or the lead/QA department.
Also a admin user (project manager, lead developer etc) could lock the whole project with exceptions for themselves or other specified users (automated build machine user etc). Do a build and test cycle and then mark it as known good release.
The source control system for the artists also allowed changes to be kept separate from the "Main Line" but kept in source control; this is like a branch if you will, but with the difference that you could allow other users or custom defined groups access to your WIP changes. This in effect is like been able to get the latest of the trunk and changes from other users branches at once.
Very useful when a group of artists, 3D modeller, texturer, animator are working on a new area as they can refine it without checking in none working bits to the main line everyone else is working on.