Interview with Tom Lord of Arch Revision System

comforteagle writes "Every revision control system has its supporters and detractors, but none is as polar as Arch. Either you hate it or think it is the best thing in revision control ever. Built more around what our beloved kernel hackers use (BK), Arch is definitely a departure from CVS and Subversion. I've interviewed Tom Lord, Arch's daddy, about the application, and he has some -ahem- interesting answers and opinions."

Comments

Glad to see....

[GillBates0]

Support Services (coming soon...)
* Per Incident
* Subscription
* Deployment Services
* Custom Development

that they're considering starting Support services soon. As a Configuration Management guy at a fairly large company, one of the reasons major corporations choose commercial version control software (Rational ClearCase, etc) over the open source counterparts (CVS, etc) is primarily due to lack of formal support.

I'm all for open source and even dislike it when companies reject Linux because of "lack of support" (this is ofcourse changing with RedHat's efforts), but experience has taught me that not everybody in a large organization is a hacker and willing to figure out the intricacies incase something goes wrong. They'd rather pay for a service contract incase anything goes wrong.

And ofcourse, there's also the accountability angle (which I dislike) to it, when you're using the version control software to develop critical/huge amount of bread-and-butter software - companies want to be able to have someone to point fingers at incase something messes up.

Re:All that and he doesn't explain...

[omaha]

As to svn backends... I think it is prudent to point out a false statement made by Lord.

from: http://web.mit.edu/ghudson/info/fsfs/

"FSFS" is the name of a Subversion filesystem implementation, an
alternative to the original Berkeley DB-based implementation. See
http://subversion.tigris.org/ for information about Subversion. This
is a propaganda document for FSFS, to help people determine if they
should be interested in using it instead of the BDB filesystem.

and from http://subversion.tigris.org/svn_1.1_releasenotes. html
"Non-database repositories

It's now possible to create repositories that don't use a BerkeleyDB database. Instead, these new repositories store data in the ordinary filesystem. Because Subversion developers often refer to the repository as "The Filesystem", we have adopted the rather confusing habit of referring to these new repositories as "fsfs" repositories... that is, a Filesystem implementation that uses the OS filesystem to store data."

arch is...

[EsbenMoseHansen]

The good things about arch is:

1. Changeset orientation --- patches are project oriented, not file-oriented, which is better (IMHO)
2. Easy to make a private branch of a repository which you do not have access to
3. Supposedly good merge mechanism
4. Revisions are stored as simple changesets (patches) with only tarring and bzip2'ing.
5. It has a lot of advanced features.

The first two are why I use arch. The bad things are

1. In Tom Lord's words, tla (the arch implementation) is a box of sharp knives. In other words, the interface is dangerous, uncomfortable, extremely badly documented and very clunky. E.g. simple operations like switching branch requires several commands and until all commands are executed the local version is in an inconsistent and unusable state
2. It's very slow. When working from a local repository, it feel roughly like cvs on a public mirror. A patch to partly fix this was rejected.
3. It uses just about every character available to the UNIX file system, including comma, =, {,} and more, and generates insanely long name. Some work is supposedly going on to fix the long names, though.
4. To use safely, you have to know some graph theory. (I do, but I don't believe everyone should)
5. Some commands are only safe if you have perfect knowledge of other users actions (star-merge).

Oh yeah, the development has just sun-flared just when it had begun starting up again. A huge flame war (where Tom's primary contribution seemed to be "Grow up", "You're childish" and worse) arch is now without a release manager, and understandable nobody wants to take that role.

In short, arch has great promise, but needs some drastic changes.

Re:I'm left out...

[Humble Legend]

I used Bitkeeper for about two weeks, before being told that since I'd said this on the arch list: "I'd cringe if I had to use Bitkeeper", and because of my public pro-stance on free software (as they had researched from my homepage - http://www.souldound.net/), I was on their shitlist and they would not sell me, and therefore the company I currently work for, a license to use Bitkeeper.

Needless to say, I found this a little confronting, took stock of my temporary moral slip in even considering the use of proprietary software (forgive me Free Software gods), and promptly got stuck into arch/tla, which I've now been using for about a month.

In my experience, tla is more flexible - the design really does reach high, although the learning curve (at the moment at least) is a little higher for sure - you really do have to go read the tutorial, wiki, etc. I found the people on the gnu-arch-users@gnu.org mailing list to be very helpful though - even if personal/ power tiffs were going on, those involved never ceased to be supportive in replying to my questions.

Hope that's a useful datapoint,
Zenaan