Underexposed

Releasing 8.6 million lines of source code and expecting open-source programmers to join Google in its development is a technological challenge.

But when Google does make its Android mobile phone software an open-source project later this year, it looks likely it will take a page from the Linux playbook and use a tool called Git to manage that part of the work.

Linux leader Linus Torvalds originally developed the Git source-code management software in 2005. He didn't like available open-source tools for the chore, but encountered resistance in using a proprietary tool, BitMover's BitKeeper.

Torvalds liked the distributed approach enabled by BitKeeper and Git, in which individuals could maintain their own "trees," variations of a project that branch off a main trunk. Git also can be used to track and manage software patches sent "upstream" by contributors working on code branches to the programmers responsible for maintaining various open-source projects.

Google currently uses a source-code management tool called Perforce to manage Android, but the company is moving to another code repository technology in preparation for moving Android into an open-source project, said Android leader Andy Rubin.

"We need an open-source repository. Currently we're on Perforce. That has to be moved to Git," and there's an effort now to make the transition, Rubin told me in an interview about Android.

That sounded to me like Android had settled on Git, but Rubin wasn't willing to go that far. "We have no announcements at this time," he said.

Maybe we'll hear more at the Google I/O conference next week for programmers interested in Google's work. One theme of the conference is Android.

Benjamin Lynn of Google's developer programs group offered a basic guide to Git on a Google open-source blog posting this week. And Google uses Git elsewhere, for example, to help Linux kernel programmers with support for Qualcomm mobile phone processors.

Junio C. Hamano currently maintains Git.

One choice Google won't pick for source code management is the centralized Subversion software.

"Subversion we don't think is enough of a repository to handle 11 million lines of code. If this is adopted, and there are 10,000 people checking out, it'll die," Rubin said. (Android today consists of about 8 million lines of Linux code plus 11 million lines of higher-level code; of the latter, about 8.6 million will become open-source software.)