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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."
What we did to arrive at that number was to simply measure the amount of change over the two-year period in BitKeeper and contrast that with the two-year period before BitKeeper. It worked out to about 2.5x more change.
I'm no mathematician but I'd say that's a decent way of estimating their productivity increase. But does BitKeeper actually help that much? Anyone who has every used it in a production environment please comment.
Linus is processing around 50 patches a day, 365 days a year.
That's a pretty incredible number. If that's the truth, then I'm very impressed.
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Although there are no hard numbers, the estimates are that Linus has been 10x more productive with BK.
And I'm 1000x more productive with CVS!
Instead of pulling numbers out of the air, just say the guy likes the tool and performs better with it. Sheesh.
Javascript + Nintendo DSi = DSiCade
Yes, methamphetamine.
Give me Classic Slashdot or give me death!
Why there was an uproar over this. Who cares if it's Free or not? It gets the job done better, and in the end that's what counts. The flame wars all over LKML and other places were just wastes of time.
BLING BLING. Meet the architecture that's changing everything.
The lesson to be learned here is very simple...
Open source and propriety software can and should be used hand in hand. The best tool for the job etc. etc. The OSS scene suffers from the idea they are members of some religion and by using anything other then Open Source they are committing a crime against the movement.
Please do not let scientific accuracy interfere with the intended humourous/interesting/insightful value of this comment
BitKeeper is a fine product. Check out the other fine products in the same product line:
*BitCreeper debugging tool
*BitSleeper archiving tool
*BitDeeper anti-anti-enhancement spam tool
*BitPeeper anti-anti-porn tool
-[joke removed for your safety]-
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.
Actually, it's meaningless without looking at other factors. Even the concept of more change is so open ended it tells us nothing. As Linux gains users it will certainly increase in these numbers, there is no strong indication that bitkeeper is a factor at all, or how much of a factor it is.
Although there are no hard numbers, the estimates are that Linus has been 10x more productive with BK.
Following the statement that there are no hard numbers , the ten percent figure seems more like a number pulled out of thin air and selected to not be large enough to be called outrageous but big enough to encourage people to make a change. That's not to say we are not talking about a good tool here (I have no opnion on that issue), but this is much more hype than a valid study.
I'm an American. I love this country and the freedoms that we used to have.
The monotone project needs developers to create a free software tool solving the same problem. We really do need good tools that are free.
Folks -- the 10x productivity number mentioned in the article was only an anecdotal claim; Larry McVoy claimed 2x. And the latter number is backed up by some pretty fair reasoning. I RTFA and didn't get the impression anyone was pulling numbers out of their ass.
S
Unlike a lot of you, Linus isn't a Linux zealot. He's said on more than one occasion that Linux/OSS is about making the right tool for the job when one doesn't already exist. It has nothing to do with shoving an ideology down everyone's throat.
In this case, Linus decided that Bitkeeper was the best tool for the job, and it is very telling that people are judging him for not complying with an almost religious ideology that he doesn't even subscribe to.
"Ask not what your country can do for you." --John F. Kennedy
There has been a noticable improvement in the 2.5-2.6 cycle compared to 2.3-2.4. Linus and the team has done a super job. Bitkeeper gets a lot of credit for it. I can't help but wonder if similar results would not have been achieved with CVS, Subversion, or arch. Are there any features Bitkeeper has that the free alternatives do not?
The GCC project is of comparable complexity to Linux. They use CVS with some success, don't they?
an ill wind that blows no good
IIRC he was not using any SCM at all so yes using one in gneral will help. CVS for me was able to get my team about 10x better (but then again I did most of the work anyways and this was for class).
But anything not using a SCM will be helped by using one.
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.
"When we are testing out a new release we can put it on bkbits.net and we know in seconds if we have broken something important; people use old versions of BK to talk to bkbits.net every few seconds."
I'm sure they're experts in code management, but their testing procedures could use some work.
In all matters of opinion, our adversaries are insane. -Oscar Wilde
Remember that this number is about perception. Linus himself says he's more than twice as productive. The other developers say he's 10x as productive.
But what's their measurement? The number of patches from them he accepts. For years, Linux development was badly hamstrung by the fact that Linus couldn't work fast enough. The patch submission process, was, in essence, emailing him over and over and over, hammering away at the poor guy, trying to get your patch noticed. The developer frustration with this process was EXTREME. The single most common thing I heard about kernel development was "Linus doesn't scale". BK has changed that completely.
It seems entirely possible to me that Linus is now 10x better at processing and merging patches. But that's not all he does.... a 10x improvement in patch management could easily translate to a 2x overall productivity increase. Measurements of code changes show about a 2.5x overall improvement, which is pretty close to Linus' own guess.
In other words, these numbers aren't incompatible... productivity is a hard thing to measure, and there are a lot of angles from which you can look at it.
If the claim of 50 patches a day, 365 days a year are true... that's 18,250 patches a year. The fact that he can do that and get coding done TOO should be an object of reverence and awe.
Since BK was designed with Linus in mind, it probably won't affect other programmers as dramatically as it did him. Not all coders will think like he does, and his distributed coding needs are very specialized. It's not going to be applicable to all environments, but it's pretty obvious that at least in some cases, it is an enormous win and completely worth what they're charging for it.
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.
Idealism is nice and all but it doesn't get shit done.
Unless you've used BK you really have no idea just how much more powerful it is than everything else. And yes, the p2p model that BK seemingly employs is a big part of it, but only a part of it.
BK has beautiful diff and merge tools. It has incredible file history tools. But most importantly, it's best at doing it's job: accurate revision control while staying near completely out of your face. That's why we used it at SOMA, and that's why I really wish we used it at Alias. Of course, all this really just scratches the surface.
Try it. Check in code. Share it with others. Propogate changes between people. Imagine sharing a development branch served off your desktop without doing any setup other than typing "bkd". Imaging 10 people pushing and pulling code between themselves and the server. Now you understand BK. It's not that source is stored or even the toolset alone. It's the fact that umpteen developers can push and pull between themselves and/or the server and accurately propogate changes all around. Combine that with the tools Larry and crew have written, and now you'll understand why it's better.
And to be fair, I work in the field and I've used SourceSafe, CVS/RCS, BitKeeper, Perforce, ClearCase, arch, Subversion, Accurev, and others. BK is easily the best of them... by far!
--ck