Re: [Qemu-devel] [RFC PATCH 0/2] port network layer onto glib

[Peter Maydell <peter.maydell@linaro.org>]

On 19 March 2013 09:30, Markus Armbruster <armbru@redhat.com> wrote:
> Coroutines are a perfectly pedestrian control flow construct.

In some languages, sure. Not in C, and we're writing C.

> Coroutines fit about as well with C as threads, namely not really.

Threads are supported by the language runtime provided on all
the systems we support, which is why they are reasonably usable.
When you've persuaded glibc, MacOSX libc and Windows to implement
coroutines please come back and let me know :-)

> If portable coroutines in C really was an intractable problem, the
> solution could not be "no more coroutines, please", only "no coroutines,
> period".  As long as we have to pay the price for coroutines anyway, I
> can't see why we should deny ourselves the benefits.

I'd like to see coroutines gone completely. The first step is not
to let them get used more than they are already.

> C programs have been doing coroutines since forever, using either hand
> coded assembly language stack switching, sigaltstack() trickery,
> ucontext(), w32 fibers, or some coroutine library built on top of these.

...and there's a wide range of really nasty options because none
of them are actually decent solutions to the problem.

-- PMM