2.6, 3.0, and truly independent intepreters

[greg]

Glenn Linderman wrote:

> If Py_None corresponds to None in Python syntax ... then 
> it is a fixed constant and could be left global, probably.

No, it couldn't, because it's a reference-counted object
like any other Python object, and therefore needs to be
protected against simultaneous refcount manipulation by
different threads. So each interpreter would need its own
instance of Py_None.

The same goes for all the other built-in constants and
type objects -- there are dozens of these.

> The cost is one more push on every function call,

Which sounds like it could be a rather high cost! If
(just a wild guess) each function has an average of 2
parameters, then this is increasing the amount of
argument pushing going on by 50%...

> On many platforms, there is the concept of TLS, or thread-local storage.

That's another possibility, although doing it that
way would require you to have a separate thread for
each interpreter, which you mightn't always want.

-- 
Greg