It's not yet time to anoint git, or anything else

[Eric S. Raymond]

I'm glad there is active discussion of distributed VCSes happening 
on the list, as I strongly believe we should move to one in the 
near future.  

But I think it's worth noting that pretty much all the good things
being said about git apply equally to other DVCSes such as Mercurial, bzr,
monotone, darcs, and Codeville.  All of these have very similar basic
models based on commit-before-merge and push/pull operations.  

It is not yet time to anoint git (or anything else) as a winner, even
by implication.  We will need to carefully consider the strengths and
weaknesses of each of these systems in relation to the specific needs
of the Emacs project.

I am working on an in-depth technical survey of this space.  You
can pull it at from a Mercurial repo at <http://thyrsus.com/hg/uvc/>.
As that indicates, I am leaning towards Mercurial for my own work --
but I intend to do a lot of research and testing before making a
final decision, and the results of my research will go into
that paper.

So far, I have done comparative evaluations of SCCS, RCS, CVS,
Subversion, Arch, and Monotone.  I intend to do similar ones of SVK,
git, bzr, darcs, Mercurial, and Codeville.  If I can get an evaluation
copy I will do Bitkeeper as well -- yes, it has a closed--source
license and there is thus no way I would recommend it, but it is of
some historical importance.

I also intend to write a test suite that will exercises all of these
in some known problem areas, especially near renames.  If I can 
come up with any way to do meaningful benchmarks, I will do that too.

So far, the only conclusion I am prepared to assert is that monotone,
darcs, and Codeville are not at present production-quality tools. I
am surveying them anyway because they have some important ideas in
them, and it is possible that they might become production-quality
tools in the future.

This leaves git, bzr, and Mercurial as near-term candidates for
production use from among the DVCSes.  All three have strikingly
similar functional models, though git is perhaps a bit more distant
from Mercurial and bzr than the latter two are from each other.

When my survey is done, we'll be in an extremely strong position to
make a selection based on hard facts and rigorous comparative analysis.
Until then, it's not time to choose among them or get too attached 
to any particular one.

(I would, by the way, welcome collaborators and reviewers to help
finish the survey.  It's a large job.  More hands would help.)
-- 
                <a href="http://www.catb.org/~esr/";>Eric S. Raymond</a>

"Say what you like about my bloody murderous government," I says,
"but don't insult me poor bleedin' country."    -- Edward Abbey