threading and iterator crashing interpreter

[Janto Dreijer]

On Mar 11, 3:27 pm, "Gabriel Genellina" <gagsl-... at yahoo.com.ar>
wrote:
> En Sun, 11 Mar 2007 09:47:34 -0300, Janto Dreijer <jan... at gmail.com>
> escribió:
>
> > As far as I can tell I'm not running it from restricted mode
> > explicitly.
>
> This error is rather strange then:
>
> > > RuntimeError: instance.__dict__ not accessible in restricted mode
>
> "restricted mode" means that the current builtins are not the standard
> builtins.

Googling says "Some googling suggests that this error is a hint that a
Python object created in one subinterpreter is being used in a
different subinterpreter."

> > The reason I'm doing the random.choice() is so I don't have a handle
> > ("session" in this case) that would prevent it from being garbage
> > collected. I am not bothered by the Python-level Exceptions. I am
> > bothered by the interpreter throwing a segfault. What I suspect is
> > happening is the Session object is deallocated, while it still has a
> > reference from within the iterator.
>
> But on your code Session objects are never deleted; they stay inside
> System.sessions. Having an extra reference (the session variable) doesnt
> matter.

Hmmm. You're right.

> > It's quite difficult to reproduce these bugs consistently. You might
> > need to run it a few times.
>
> At least, the problem of using the same generator from different threads
> still remains, if you don't use my modified code. In general, when using
> multiple threads you always need some way to syncronize access to shared
> objects. You are lucky with Sessions because append is an atomic operation
> on lists; for more information see  http://effbot.org/pyfaq/what-kinds-of-global-value-mutation-are-threa...

Again you're right. But even putting a try-except:return around the
random.choice still manages to break the interpreter. I'm not looking
for any meaningful output really. I just want it not to break.

Like I said, this is just watered down code to try and isolate the
problem.