On 11/6/06, Joshua Haberman <joshua / reverberate.org> wrote:
> On Mon, 2006-11-06 at 13:55, Brian Mitchell wrote:
> > I agree enough with some of that though I wouldn't say Darcs doesn't
> > scale well (in comparison to svn) at this point.
>
> After I heard about the "poison patch" problem with Darcs, I basically
> stopped using it immediately and considered it unsuitable for pretty
> much anything.  I don't know how well-documented this problem is, but
> here is how one random person describes it:
>
> http://sayspy.blogspot.com/2006/08/comparing-mercurial-to-bazaar-ng.html
>
> "Well, Darcs suffer from a little advertised problem, known as the
> "poison patch". With a Darcs repo, you can end up in a situation where a
> particular checkout will take hours to days (and maybe eventually fail).
> This happened to one of my important Darcs-controlled project, and I can
> assure you that once it happened, you don't want to happen again. I
> should add that it is not predictable, so it can happen anytime."
>
> Yes, this is a informal comment on someone's blog, but I also see the
> problem referred to in this post to darcs-users, along with a proposal
> to address the problem:
>
> http://www.abridgegame.org/pipermail/darcs-users/2006-February/009454.html
>
> "I think there is a
> lot of potential here, but kept my initial proposal very basic and the
> minimum to help prevent the 'poison patch' problem which has been a
> serious issue in practice."
>
> I know my sources are somewhat hearsay, but I find this problem
> believable given what I know about Darcs and its theory of patches.  I
> would be very wary of trusting anything to a system that unpredictably
> becomes unusable.

After some research into the topic:

That problem is real but it is quite misrepresented in the blog post.
Poison patches are a generalized name for a few problems that emerge
from bad practices or sloppy management. Here is a FAQ entry that
notes the few problems that cause such things:

http://darcs.net/DarcsWiki/FrequentlyAskedQuestions#head-76fb029ff6e9c20468eacf3ff00d791e2cf03ecb

I've not had problems myself but they are there. Darcs is different
enough that some people feel like it is random. Fortunately, it seems
documented enough to avoid or at least solve.

Brian.