[pypy-dev] some questions

[Aurélien Campéas]

On Thu, Dec 21, 2006 at 05:44:00PM +0100, Armin Rigo wrote:
> Hi Aurelien,
> 
> On Tue, Dec 19, 2006 at 06:50:46PM +0100, Aur?lien Camp?as wrote:
> > * is there a chance that a peer review and eventual correction/advice
> > on that non-working code can yield a working solution in a reasonnable
> > amount of time ?
> 
> No.  Getting the original coroutine cloning code to really work
> correctly took us quite some time, and certainly more than 10 days,
> including a final night following data structures at the C level with
> ddd.  (Btw, that's a gdb front-end that I really recommend for Debugging
> and Displaying Data :-)  It looks innocent enough but it is really
> subtle code, so you should try to build on top of that and not reinvent
> it from scratch.

I never meant to reinvent this from scratch. You also said to me
recently that the local pooling was not especially tied to coroutines,
which matched the intuition I had from reading the interp_clonable
stuff.

> 
> Note also that if you need sets of several coroutines that are all
> cloned together, it's possible to put each set in a single
> InterpClonableCoroutine that acts as a "big" thread; and it would itself
> contain several regular Coroutines for its own local purposes.  This
> works nicely if in each InterpClonableCoroutine you first create a new
> CoState() instance, and use it as the 'state' argument of all the local
> Coroutines.  This local CoState has a current and a main that are local
> too.  If you clone one of the "big" InterpClonableCoroutine, everything
> will be cloned - the local CoState and its Coroutines.

Some time ago I tried that road but abandonned it because it yielded
non-working builds. But at that time I missed the "this works nicely
if ..." part. Thanks for taking the time to talk about it.

> 
> Hum, actually for now that's theory only.  The local Coroutines have a
> __del__ and objects with a __del__ are never cloned.  I guess that my
> point is that we could make this work with minimal efforts (e.g. with a
> variety of Coroutines that doesn't need a __del__).

I don't think in my usage of Coroutines I need a __del__. So maybe
there is a tiny hope.

> 
> > The later option would entail throwing away ten days of work, and
> > spending a more days to reorganize and rewrite stuff, but can be done
> > while retaining a reasonnable amount of functionnality.
> 
> Well, I would have given you the same answer 10 days ago, or even a few
> months ago, if only I had known.  I should point out that we ("the
> technical board") tried to ask Logilab in general to tell us what plans
> they had, and we tried quite a few times now, 

Logilab's plan wrt WP9 have always been clear I think, but
whatever. Talking about logilab relationships with the PyPy group is
for another day.

> so I fail to feel bad
> about telling you now to throw away just 10 days of work, sorry.

Well, sorry if you interpreted my poor wording about days of work
being thrown away as an attempt to culpabilize you. That was not my
intent. Moreover I highly respect what you have done for the cloning
facility and everything in general the core PyPy developpers have
achieved so far.

Thanks,
Aurélien.