[Zope-dev] Zope 2.7 running with Stackless 3.0

[Michael Hudson]

Shane Hathaway <shane at zope.com> writes:

> On 08/27/2003 07:55 PM, Christian Tismer wrote:
> > just by chance, I got into the position to try out
> > Zope 2.7.0 beta 1/2, and since it needs Python 2.2.3
> > at least, and Stackless 3.0 was just ported to that, I tried
> > to build Zope with Stackless 3.0.
> > It works very very well! After a few patches to get the includes
> > right, here the installation instructions.
> 
> I am in awe.  Cool. :-)
> 
> However, I am also a little confused.  As I understand it, Stackless
> needs all C code to be non-reentrant, i.e. C code must never call back
> into Python.  But Zope has a lot of reentrant code, especially in
> Acquisition and ZODB.  Doesn't that prevent Zope from taking advantage
> of Stackless continuations?

I think this is the magic of stackless 3: it uses assembler to move
pesky bits of the C stack away in some circumstances.

Not all C code can safely have this done to it, mind, but most can
(how often do you take the address of a stack variable and expect it
to be valid for an extended period of time?).

Cheers,
mwh

-- 
   This proposal, if accepted, will probably mean a heck of a lot of
   work for somebody.  But since I don't want it accepted, I don't
   care.                                   -- Laura Creighton, PEP 666