On Tue, Jan 19, 2021 at 10:08 AM Mark Shannon <m...@hotpy.org> wrote:
> > > On 19/01/2021 5:48 pm, Guido van Rossum wrote: > > I'm not clear on how you plan to implement this in CPython. > > > > I can totally see that if a Python function calls another Python > > function, you can avoid the C stack frame and hence you can have as many > > Python call levels as you want. > > > > However, there are many scenarios where a Python function calls a C > > function (e.g. `filter()`, or `dict.__setitem__()`) and that C function > > at some point calls a Python function (e.g. the `__hash__()` method of > > the key, or even the `__del__()` method of the value being replaced). > > Then that Python function can recursively do a similar thing. > > Indeed, that is the second case below, where a Python __add__ > function recursively performs addition. Most likely, the C stack will > get exhausted before the recursion limit is hit, so you'll get a > StackOverflow exception. > > > > > Are you proposing to also support that kind of thing to go on for a > > million levels of C stack frames? > > No, most likely 10k to 20k calls before a StackOverflow exception. > Okay, that helps my understanding of the proposal. So StackOverflow really means "C stack overflow"? And the plan seems to be - no intervening C frame for Python-to-Python calls - fix all C code to explicitly check for stack overflow (even in `__del__`) - decouple RecursionError (Python) from StackOverflow (C) If you can pull that off I am all for it. -- --Guido van Rossum (python.org/~guido) *Pronouns: he/him **(why is my pronoun here?)* <http://feministing.com/2015/02/03/how-using-they-as-a-singular-pronoun-can-change-the-world/>
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