[python-committers] Survey about DVCSs compared to svn

[M.-A. Lemburg]

On 2009-02-26 15:50, Antoine Pitrou wrote:
> Hi,
> 
> I'm no trying to advocate switching to a DVCS, but really:
> 
>> I think that's a much better approach and one that reduces the
>> load on the python.org repo sys-admins.
> 
> How does having 4 more-or-less supported VCSes, rather than 1, lighten
> the load on the sysadmins? Even though the DVCSes are theoretically
> handled by separate people, they have needs which must be fulfilled by
> the sysadmins (e.g. for Mercurial, mod_wsgi had to be installed for the
> Web front-end; and we see how much cooperation Bazaar support seems to
> require from the sysadmins).

I didn't know that and was under the impression that those other
systems simply hook up to the svn repo via the standard Subversion
interfaces.

>> Another aspect to consider is that Subversion uses copy-on-write,
>> so that creating a branch with only a few changes doesn't take
>> up much space in the repo.
> 
> Other systems like Mercurial (and I'd be surprised if the others didn't
> have that option as well) also use copy-on-write when creating clones of
> a repository. You shouldn't assume that SVN has optimizations that the
> others don't have. SVN is actually quite crappy performance-wise (at
> least compared to Mercurial, which I'm used to).

I wasn't trying to imply that the other system don't support this.

However, it is often said that branches in DVCS system are so much
better to work with. Subversion supports these as well, it's just
that we currently don't make much use of them and that's what I
wanted to point out.

>> BTW: You can avoid the extra checkout of the branch in Subversion
>> by first locally copying the trunk checkout to a new dir (using e.g.
>> cp -al) and then running a "svn switch" on it.
> 
> That means you only work on one feature at a time, though (since you
> can't locally commit your changes).

I don't understand that comment. Of course, you can commit whatever
changes you make to the branch. It's not done locally and then forwarded,
but that's not really a technical disadvantage, it's merely a different
way to work.

By contrast, the reasons for switching from CVS to Subversion were
mostly technical ones - we often had problems with locks and tagging
was very slow.

> Besides, every time you switch the
> source URL you have to "make distclean", which makes builds quite a bit
> longer.

Why is that ? You need to do that for patches that change the build
system or configuration, but for patches to a single C file, that's
normally not needed.

-- 
Marc-Andre Lemburg
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