[Python-Dev] Threading and callbacks - missing documentation

[Thomas Heller]

From: "Martin v. Loewis" <martin@v.loewis.de>
> "Thomas Heller" <thomas.heller@ion-tof.com> writes:
> 
> > Can't you at least partly combine the advantages of 1 and 2 by using
> > thread local storage for the global variable? I have no idea if there
> > is a portable way to do this...
> 
> That would work, but, as you already guess: there is no portable way
> to do this. If you can accept platform-specific code, this is a good
> idea.
> 
[in another message]
> The pthreads equivalent of Windows TLS is
> pthread_getspecific/setspecific, so you could cover pthreads and Win32.

Normally I don't care too much about portable code, but in this case
(storing and retriving the current threadstate between calls to C code
and callbacks from C-code into Python code) the most benefits could
only be gained if the Python core and hopefully also extension developers
cooperated and used this method.

Maybe the Py_BEGIN_ALLOW_THREADS and Py_END_ALLOW_THREADS macros
could be changed to store the threadstate in a global TLS area for
Windows and pthreads platforms?

Thomas