Re: guile fibers - looking for adivce

["Aleix Conchillo Flaqué" <aconchillo@gmail.com>]

On Tue, Sep 8, 2020 at 12:48 AM Chris Vine <vine35792468@gmail.com> wrote:

> On Mon, 7 Sep 2020 17:25:38 -0700
> Aleix Conchillo Flaqué <aconchillo@gmail.com> wrote:
> [snip]
> > To be honest, I've never used GOOPS so things might be a bit more
> > complicated there, I don't know. But it sounds like you have two options:
> >
> > - Create a fiber with the object and pass data from the object using
> > channels to other fibers. Then return data to the main fiber (or the
> fiber
> > that has the object) through a channel and update your object.
> > - Make the object global and have fibers that update the object. In this
> > case you would need to use mutexes.
> >
> > Or maybe you find another way?
>
> The OP should use channels.  It is a bad idea to mix mutexes (which are
> a construct for native OS threads) with fibers, because fibers run as
> delimited continuations, a group of which may be running on a
> particular thread.  To synchronize fibers, you use channels.
>
> Guile's atomic variables (boxes) are available and can be used with
> fibers because they do not block, but to use them you really need to
> know what you are doing, just as you do if you are using them in C.
> Atomic variables do synchronize memory, but they do not provide mutual
> exclusion (they don't block) and so require expert skills: don't use
> them if you don't know how to use atomic compare-and-swap correctly.
>
> This is what the guile fibers manual has to say:
>
> [snip]
>
>
Ooops, duh... Thank you Chris! I don't know what I was thinking when I
wrote that, I guess just about Go. Funny enough, I read that fibers section
about mutexes the day before, so it clearly didn't stick.

So, Jan, ignore my last email and stick to channels. My apologies for the
confusion.

Aleix