Threads, signals and sockets (on UNIX)

[geoffbache]

On Jun 11, 2:08 pm, Jean-Paul Calderone <exar... at divmod.com> wrote:
> On Mon, 11 Jun 2007 04:56:43 -0700, geoffbache <geoff.ba... at pobox.com> wrote:
>
> >> Twisted *should* be able to do this, as it uses non-blocking IO.
>
> >>http://twistedmatrix.com/trac/
>
> >Thanks for the tip. I'll take a look if nobody has any better
> >suggestions.
>
> Twisted is a pretty good suggestion in general. ;)
> >It still seems to me that what I'm trying to do is essentially quite
> >simple, and shouldn't require
> >as large a tool as Twisted to fix it. Isn't Twisted basically for web
> >applications?
>
> Twisted supports HTTP, but it does plenty of other things too.  Generally
> speaking, it's useful for any network application, plus some other stuff.
>

My application is only incidentally a network application. It doesn't
have clients
and servers as such, it just distributes its work via a grid engine
and then lets
these workers communicate back their results via sockets.

> You're half right about this being simple though, and not needing Twisted
> to solve the problem.  The only thing you need to do to solve the problem
> is avoid using either signals or threads.  Interaction between the two is
> very complicated and, as you've noticed, varies across platforms.  Twisted
> is solving the problem for you here by letting you do I/O without using
> threads, making signals *almost* simple.
>

Yes, I would avoid signals or threads if I could, but it's tough. The
program
is supposed to "appear" to just be a batch process, so handling e.g.
ctrl-C is essential.
The standard SocketServer doesn't allow for this, so I need some other
thread of control
that will, or some means of "asynchronising" SocketServer internally.

Or there's always the really hacky low tech solution which has a
certain appeal : have
the main thread check all the others for being alive and sleep in
between...

Geoff