Comment 5 for bug 419421

To clarify what I meant in comment #4:

I described a possible circular reference problem in bug #419408, which might be impossible to garbage collect because of the presence of __del__ methods. I don't know where the circular reference might be, I'm just speculating.

However, in the code mentioned, processes not being collected would be congruent with problems during gc. Perhaps the fix for bug #419408 will help with this bug.

That's a lot of possiblys, mights, perhapses and speculation.