[issue39907] `pathlib.Path.iterdir()` wastes memory by using `os.listdir()` rather than `os.scandir()`

[Barney Gale]

New submission from Barney Gale <barney.gale at gmail.com>:

`pathlib.Path.iterdir()` uses `os.listdir()` rather than `os.scandir()`. I think this has a small performance cost, per PEP 471:

> It returns a generator instead of a list, so that scandir acts as a true iterator instead of returning the full list immediately.

As `scandir()` is already available from `_NormalAccessor` it's a simple patch to use `scandir()` instead.

----------
components: Library (Lib)
messages: 363689
nosy: barneygale
priority: normal
severity: normal
status: open
title: `pathlib.Path.iterdir()` wastes memory by using `os.listdir()` rather than `os.scandir()`
type: resource usage
versions: Python 3.9

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue39907>
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