[Python-Dev] Extension modules, Threading, and the GIL

[Aahz]

On Sun, Dec 29, 2002, David Abrahams wrote:
>
> Python extension module B calls shared library Q and uses Q's callback
> interface.  Because some of the callbacks need to use the Python API,
> and *might* be invoked by threads, they must all acquire the GIL.
> Because they also might be invoked by direct calls into Q, B must
> always release the GIL before calling anything in Q.

So you're saying that the callback functions in B acquire the GIL?

> Problem: using B while A is loaded breaks A: because B has installed
> callbacks in Q that acquire the GIL, A must also release the GIL
> before calling into Q.

Why?  The callbacks in B will simply hang until they acquire the GIL.

I think this thread might be better handled on c.l.py, at least until
it's understood well enough to be clear whether something does need to
change in Python.
-- 
Aahz (aahz@pythoncraft.com)           <*>         http://www.pythoncraft.com/

"There are three kinds of lies: Lies, Damn Lies, and Statistics."  --Disraeli