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. Are you proposing to also support that kind of thing to go on for a million levels of C stack frames? (Do we even have a cross-platform way of avoiding segfaults due to C stack overflow?) On Tue, Jan 19, 2021 at 5:38 AM Mark Shannon <m...@hotpy.org> wrote: > Hi everyone, > > It's time for yet another PEP :) > > Fortunately, this one is a small one that doesn't change much. > It's aim is to make the VM more robust. > > Abstract > ======== > > This PEP proposes that machine stack overflow is treated differently > from runaway recursion. This would allow programs to set the maximum > recursion depth to fit their needs and provide additional safety > guarantees. > > The following program will run safely to completion: > > sys.setrecursionlimit(1_000_000) > > def f(n): > if n: > f(n-1) > > f(500_000) > > The following program will raise a StackOverflow, without causing a VM > crash: > > sys.setrecursionlimit(1_000_000) > > class X: > def __add__(self, other): > return self + other > > X() + 1 > > ----------- > > The full PEP can be found here: > https://www.python.org/dev/peps/pep-0651 > > As always, comments are welcome. > > Cheers, > Mark. > _______________________________________________ > Python-Dev mailing list -- python-dev@python.org > To unsubscribe send an email to python-dev-le...@python.org > https://mail.python.org/mailman3/lists/python-dev.python.org/ > Message archived at > https://mail.python.org/archives/list/python-dev@python.org/message/ZY32N43YZJM3WYXSVD7OCGVNDGPR6DUM/ > Code of Conduct: http://python.org/psf/codeofconduct/ > -- --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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