Parallel Dev: Should developers work within the same branch?

Question

Should multiple developers work within the same branch, and update - modify - commit ? Or should each developer have his/her own each branch exclusively? And how would sharing branches impact an environment where you are doing routine maintenance as opposed to unmaintained code streams? Also, how would this work if you deploy each developers work as soon as it is done and passes testing (rapidly, as opposed to putting all of their work into a single release).

Answer 1

In general, I have found that having developers (who are working on the same project) use the same branch is better for finding integration problems sooner. If developers are each using an individual branch, then you're just delaying possible integration problems until later, when you merge the branches.

Of course, having developers work on the same branch means you need to have actual communication between those developers, but that's a social problem and not a technical one.

Developers would work on separate branches when there is a good reason for that branch to exist in the first place (such as a patch release of a previous version of the software, or a special build for a specific customer).

Note that tools such as Git and Mercurial allow developers to easily create their own private branches to organise their own work. This is a different situation from more than one developer sharing a branch, and (usually short-lived) private branches should be encouraged.

Answer 2

Branches are meant as a way to version control any feature or experimental piece of code that may break the mainline/trunk.

While it is common for developers to have their own personal branches for deep experimentation, often branches center around a new feature being added. These new features often require more than one person to be committing.

For example, on a web project, two developers and a designer may be doing a facelift to their company website. They still need to keep their mainline/trunk code clean in case they need to make a quick change to it before the facelift is complete. So they create a "facelift" branch and work on that instead. While the developers are committing javascript, the designer can be committing CSS and images. Once the facelift feature is complete, they can merge it into the mainline and send it live.

The only reason any of them would need personal branches would be for experimenting. Perhaps the designer is trying to implement "sliding door" tabs and can't get the padding right in IE6, for example. If he solves the problem, he can merge it into the facelift branch, if he can't, he simply ignores it and continues with the rest of the design back in the facelift branch.