The move could slow Linux development as Torvalds reverts to a less automated system based on e-mail, he said Wednesday in postings to the Linux kernel mailing list. But it's better to start shifting away sooner rather than later, he said.
"I've decided to not use BK (BitKeeper) mainly because I need to figure out the alternatives," Torvalds said in a posting. "Rather than continuing 'things as normal,' I decided to bite the bullet and just see what life without BK looks like."
Linux leader Linus Torvalds has begun looking for a replacement for the BitKeeper system to house and manage the complicated, global programming effort. The move addresses gripes from some in the open-source and free software community about the proprietary nature of BitKeeper.
A shift back to an older e-mail based control method likely will disrupt and slow some Linux development, but Torvalds says it's better to start shifting away from BitKeeper sooner rather than later.
But at a minimum, there will be significant disruptions for the many Linux developers who have grown accustomed to using BitKeeper to shuttle modifications called "changesets" up and down the programmer hierarchy.
There are more than 10,000 active versions of the Linux kernel in an interconnected system of BitKeeper repositories, said Larry McVoy, founder of the company called BitMover that sells the proprietary BitKeeper software. That's likely to change now. "I suspect that in three years some alternative will become the primary source code management system for the Linux kernel. What that is remains to be seen," McVoy said in an interview.
As the Linux programming effort has grown--McVoy now estimates there are more than 1,500 developers who have contributed to Linux components--it has gradually become more formal. Torvalds in 2004 started requiring contributors to, and began in 2002. Torvalds also has standardized his format.
Torvalds isn't fond of centralized code repositories such as those using the Concurrent Version System software, though he said that possibility shouldn't be completely ruled out. The leading alternative for a Linux management system is a project called Monotone, Torvalds said.
Why the change?
Ultimately, the shift away from BitKeeper arose because of differences between the advocates of open-source and proprietary software. BitKeeper is proprietary, so Torvalds' adoption of it rankled many open-source advocates.
McVoy supports and uses open-source software, but he's determined to protect his technology from copycats--including open-source programmers. BitMover offered a no-cost, proprietary, somewhat stripped-down version of BitKeeper that let Linux programmers use the system for free. But that led to efforts to reproduce its abilities, which McVoy spurned. On Wednesday, BitMover announced it will discontinue that free product, instead offering only an open-source alternative that's not powerful enough to support all Linux programmers.
"This is not an attempt to extract money from the open-source community. It's an attempt to protect our intellectual property," McVoy said in an interview. Not that he hasn't considered the value of what his company has offered: In a February posting, McVoy estimated that Linux programmers' use of BitKeeper software would cost at least $65 million per year.
Among those who criticized Torvalds' adoption of BitKeeper was Richard Stallman, the programmer who founded the Free Software Foundation to promote software that's free of such proprietary constraints. In 2002, he suggested creating free software that could interoperate with BitKeeper.
Recently, , a lead programmer for the open-source Samba project and, like Torvalds, an employee of Open Source Development Labs (OSDL), has begun work to do just that. However, he hasn't publicly released the software, called SourcePuller.
"I did write a tool that is interoperable with BitKeeper," Tridgell said in an interview. "I did not use BitKeeper at all in writing this tool and thus was never subject to the BitKeeper license. I developed the tool in a completely ethical and legal manner."
OSDL hired Tridgell to work full-time on Samba, the consortium said in a statement. "Any other projects he pursues are his own," OSDL said.
That type of work doesn't sit well with McVoy. "All we are trying to do is (1) provide the open-source community with a useful tool, (2) prevent that from turning into the open-source community creating a clone of our tool," he said in a February posting.
BitMover, based in South San Francisco, Calif., and founded in 1998, offered free use of the software for Linux programmers for two reasons, McVoy said: to aid marketing and because he has been Torvalds' friend for more than 10 years.
And Torvalds has said the use of BitKeeper has improved Linux development dramatically. "I'm personally very happy with BK, and with Larry. It didn't work out, but it sure as hell made a big difference to kernel development," Torvalds said Wednesday. "I'm convinced it caused us to do things in better ways, and one of the things I'm looking at is to make sure that those things continue to work."