Crash report

What happened?

When creating a deeply nested chain of filter() iterators, Python 3.12 can handle it (although very slow), but Python 3.13 results in a segmentation fault instead of raising an exception.

This appears to be a regression in Python 3.13’s iterator implementation, as user code should never cause a segfault. Ideally, this should raise a RecursionError or another Python exception, not crash the interpreter.

if __name__ == '__main__':
    import sys
    import gc
    
    def main():
        i = filter(bool, range(1000000))
        for _ in range(100000):
            i = filter(bool, i)
        print(list(i))

    #sys.setrecursionlimit(1000000)
    main()

CPython versions tested on:

3.13

Operating systems tested on:

Linux

Output from running 'python -VV' on the command line:

Python 3.13.2 crashes with:Segmentation fault (core dumped) Python 3.12.9 executes successfully (though very slow).

Linked PRs

• [3.13]gh-137894: Fix segmentation fault in deeply nested filter() iterator chains #137895
• gh-137894: Fix segmentation fault in deeply nested filter() iterator chains #137896