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Bitkeeper News Redux
gosand writes "Newsforge is running Part 1 of a two-part interview with Bitkeeper author Larry McVoy. You may recall that there was quite an uproar in the community over Linus choosing to use a proprietary source management tool. Although there are no hard numbers, the estimates are that Linus has been 10x more productive with BK."
"Here's how that announcement came about. I asked someone we were considering hiring why he wanted to come work for us. His response was, "I hang out on the kernel list and it is obvious that Linus is ten times more effective since he switched to BitKeeper." That sounded pretty nice, but I didn't believe it. I knew things were better, but ten times better? That sounded a little too good to be true."
Did you bother to read the article before posting? They say the real number is closer to 2.5x.
Sheesh.
Who cares if it's Free or not?
I usually don't, butif you read the BK license, you will notice that it disallows you to work on competitors (including CVS and subversion) if you are a BK user. I think at least one of the subversion developers (who also contributes to the Linux Kernel) is not allowed to send Kernel patched using BK because of that (he sends them via email).
BK uses a more distributed development model instead of having one central server, which allows people to maintain their own version controlled source tree from which Linus (or anyone) can pull patches from. This is more like Arch or SVK than CVS or Subversion. Although in the end it performs a similar function, the difference is fairly significant.
It gets the job done better, and in the end that's what counts
I've used many peices of software that have gotten "the job done better."
And, I've been burned too many times to count when the company that makes the software changes focus or goes out of business.
Free Software, for me, is great insulation from forced migrations, "upgrades" and unsupported software.
Moneyed corporations, non-working 'poor' and criminal prisoners are turning productive citizens into tax-slaves.
The fact that it's actually used outside of one project/domain (unlike BitKeeper) also helps as there's a wider pool of experience to tap into.
Having said that, while it's maturing fast it still has an evil UI (no Tom wrappers are NOT an acceptable solution for that), and lacks some important features like being able to turn a changeset into a flat text file and then email it in one command. If you're willing to do some scripting arch is the most powerful SCM I've ever seen, but it could always be better.
Finally it's a bit misleading to say that it was BitKeeper that made Linus 10x more productive. Before BK they didn't use any source control at all, and all patches were sent either in private email or onto lkml. It's not surprising that using source control improved things!
For comparison, Alexandre Julliard who maintains Wine processes approximately 100 checkins a week, so that's about 14 a day. We use CVS with a single committer. Given that Alexandre actually codes a lot as well, I think it's pretty clear that Linus' "productivity boost" more to do with being able to work full time and having a decent project structure (we all send patches to a dedicated mailing list for instance and we don't have a ton of "lietenant" trees) than anything magical about BitKeeper.
Larry referenced some stuff I wrote for Open Source magazine recently. Here's the basic information if anyone wants to know what the real rate of change was for the 2.6 kernel development cycle. As for if it is faster than 2.4 we don't have real numbers (bk wasn't being used) but you can take the diffs and compare them for yourselves...
The Linux 2.6.0 kernel was released after 680 days of development. Here are some statistics about the development cycle during that time period:
- 27149 different changes were accepted into the kernel source tree. That averages out to about 1.66 changes per hour over the entire 680 days.
- 916 different developers contributed at least one kernel patch.
- 413 different developers contributed one kernel change.
- 117 different developers contributed two kernel changes.
- 57 different developers contributed three kernel changes.
- 38 different developers contributed four kernel changes.
- 20 different developers contributed five kernel changes.
- The top 10 developers contributed 10933 kernel changes.
- The top 5 developers contributed 6956 kernel changes, averaging out to about 10 kernel changes a day.
- There were 6175 merges in the kernel source tree, averaging out to about 9 merges a day.
- Including merges and code changes, there were just over 2 modifications per hour over the entire 680 days of development.