[JDEV] Q: Has any other threading library been considered?

[Dave Smith]

> I've been messing around with the Jlib stuff on Windows 2000 most of the
> night trying to come as close as possible to a succesful compile.  I ran
> into what I believe were several cross-platform issues that just hadn't
been
> handled yet.  However, I've never been actively involved in an
open-source,

You are undoubtedly correct. :) Pth simply won't compile on Win32 -- even
using cygwin. This is due to the way that Pth handles context switches
between the threads. At this point, it's due to the fact that the cygwin
implementation doesn't implement all the necessary POSIX calls that Pth
uses.

> cross-platform project before, so I could be mistaken (or could have made
> mistakes during modification), but I've got several modified source files.
> What should I do with them?

Hmm..what did  you modify and why? You'll probably need to talk to jer if
you've made any modifications on the Jabber core. At any rate, it would be
nice to hear what changes you've made as I've also been trying to get Jabber
over to Win32 (and BeOS -- which is also POSIX deficient).

> Windows platform, at least).  I surfed around and noticed several other
> freely available cross-platform threading libraries, and I'm wondering if
> any of these have been considered, or if there are specific reasons that
PTH
> is being used and others won't be considered.  I saw several alternatives

The current line of thought on Pth is that it allows us to use asynchronous
sockets without having to deal with the mess of polling them. Async. sockets
are especially critical server side as you really don't want to have
seperate threads for every single connection (which would get out of hand
after 1000 or so connections, due to the large amount of time which would be
spent context switching between kernel threads). :) Hence, Pth gives us a
"lightweight" solution which doesn't require super-efficient threads on the
part of the O/S

As Jer pointed out fairly early on in the project, Jabber is somewhat unique
among internet apps in that it requires long-term connections to the server.
Compare this to the approach utilized by most "modern" IM which use UDP for
message transfer, or even HTTP which uses a relatively short-lived TCP
connection for retrieving a single document. Most of the other threading
libraries you mentioned utilize kernel-level  threads which are simply too
heavy for the Jabber server (this is not to say that they shouldn't be used
for the *client* though). :)

Like you, I'm hoping to one day get the Jabber server to other platforms
(with or without Pth) I'm not sure how it's going to be done yet, but if
enough of us put our heads together, it should be possible. Unfortunately, I
don't see it as happening before 1.0. :(

Hope this helps. :)

D.