[darcs-devel] announcing darcs 2.0.0pre1, the first prerelease for darcs 2

Dmitry Kurochkin dmitry.kurochkin at gmail.com
Wed Dec 19 03:00:41 UTC 2007

I tried to get pipelining working with cURL, but no luck. It looks to me
that cURL multi API is overcomplicated and not-too-well documented...

So I have taken a look at libwww and it works great! I created (copied
a sample) simple program to load given URL many times using only
persistent connection and using pipelining. And results are much better
than I expected: loading 1000 times http://nnov.ru takes 1:29,49 with persistent
connection and only 22,946s with pipelining!

I will experiment with replacing current cURL implementation with libwww.
I am not familiar with Darcs sources, advices are welcome. After a quick
look at External.hs it looks to me like we can provide a function which takes
a list of URLs instead of one, and fetches them using pipelining. I think
this will require minimum changes to Darcs sources. Am I correct with this?


2007/12/18, Dmitry Kurochkin <dmitry.kurochkin at gmail.com>:
> After looking at this a bit more it does not look so good to me.
> I thought that darcs uses a new TCP connection for each patch. But
> wireshark shows that it uses persistent connection already.
> So there is no TCP handshake overhead.
> Pipelining is sending multiple requests without waiting for response.
> This would give some benefit but I am not sure it worth the price of
> moving to cURL multi interface.
> I think I will write a script which grabs darcs repo using cURL with
> just persistent connection and with pipelining. And depending on
> results we can decide what to do.
> Regards,
>   Dmitry
> David Roundy wrote:
> > Hmmmm.  Alas, curl 7.16 is not yet in debian stable (my default for when we
> > can require something), but that's still very interesting!  Do you by any
> > chance have experience coding with libcurl? We've only ever used the "easy"
> > interface, and if you'd like to take a shot at updating src/hscurl.c to use
> > the "multi" interface, that would be great!
> >
> > (We'd need to have a configure check so we'd work with older libcurl
> > versions, but I could handle that if you'd rather not.)
> >
> > David
> >
> > On Tue, Dec 18, 2007 at 01:06:26AM +0300, Dmitry Kurochkin wrote:
> >
> >> Hi David,
> >>
> >> According to cURL changelog pipeline support has been added in version
> >> 7.16.0:
> >>
> >> CURLMOPT_PIPELINING added for enabling HTTP pipelined transfers.
> >>
> >> I did not use it myself but from the docs it looks like this is just
> >> what you want. Quote:
> >>
> >>
> >> Pass a long set to 1 to enable or 0 to disable. Enabling pipelining on a
> >> multi handle will make it attempt to perform HTTP Pipelining as far as
> >> possible for transfers using this handle. This means that if you add a
> >> second request that can use an already existing connection, the second
> >> request will be "piped" on the same connection rather than being
> >> executed in parallell. (Added in 7.16.0)
> >>
> >> Thanks for your work on darcs (and xmonad :))!
> >>
> >> Regards,
> >>  Dmitry
> >>
> > _______________________________________________
> > darcs-devel mailing list
> > darcs-devel at darcs.net
> > http://lists.osuosl.org/mailman/listinfo/darcs-devel
> >
> >

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