From 84534f9df17f8134b0329e43a8cb5d16f9551835 Mon Sep 17 00:00:00 2001
From: barneygale <barney.gale@gmail.com>
Date: Wed, 10 Apr 2024 21:33:06 +0100
Subject: [PATCH 1/2] GH-117727: Speed up `pathlib.Path.iterdir()` by using
 `os.scandir()`

Replace use of `os.listdir()` with `os.scandir()`. Forgo setting `_drv`,
`_root` and `_tail_cached`, as these usually aren't needed. Use
`os.DirEntry.path` to set `_str`.
---
 Lib/pathlib/__init__.py                       | 25 +++++--------------
 ...-04-10-21-30-37.gh-issue-117727.uAYNVS.rst |  2 ++
 2 files changed, 8 insertions(+), 19 deletions(-)
 create mode 100644 Misc/NEWS.d/next/Library/2024-04-10-21-30-37.gh-issue-117727.uAYNVS.rst

diff --git a/Lib/pathlib/__init__.py b/Lib/pathlib/__init__.py
index 88e3286d9b08dc..f64befd03360f2 100644
--- a/Lib/pathlib/__init__.py
+++ b/Lib/pathlib/__init__.py
@@ -584,7 +584,12 @@ def iterdir(self):
         The children are yielded in arbitrary order, and the
         special entries '.' and '..' are not included.
         """
-        return (self._make_child_relpath(name) for name in os.listdir(self))
+        root_dir = str(self)
+        with os.scandir(root_dir) as scandir_it:
+            paths = [entry.path for entry in scandir_it]
+        if root_dir == '.':
+            paths = map(self._remove_leading_dot, paths)
+        return map(self._from_parsed_string, paths)
 
     def _scandir(self):
         return os.scandir(self)
@@ -599,24 +604,6 @@ def _make_child_direntry(self, entry):
         path._tail_cached = self._tail + [entry.name]
         return path
 
-    def _make_child_relpath(self, name):
-        if not name:
-            return self
-        path_str = str(self)
-        tail = self._tail
-        if tail:
-            path_str = f'{path_str}{self.parser.sep}{name}'
-        elif path_str != '.':
-            path_str = f'{path_str}{name}'
-        else:
-            path_str = name
-        path = self.with_segments(path_str)
-        path._str = path_str
-        path._drv = self.drive
-        path._root = self.root
-        path._tail_cached = tail + [name]
-        return path
-
     def glob(self, pattern, *, case_sensitive=None, recurse_symlinks=False):
         """Iterate over this subtree and yield all existing files (of any
         kind, including directories) matching the given relative pattern.
diff --git a/Misc/NEWS.d/next/Library/2024-04-10-21-30-37.gh-issue-117727.uAYNVS.rst b/Misc/NEWS.d/next/Library/2024-04-10-21-30-37.gh-issue-117727.uAYNVS.rst
new file mode 100644
index 00000000000000..3a0b6834e91f18
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2024-04-10-21-30-37.gh-issue-117727.uAYNVS.rst
@@ -0,0 +1,2 @@
+Speed up :meth:`pathlib.Path.iterdir` by using :func:`os.scandir`
+internally.

From 8bec7c88ccbc1cb9fb75fc14cec07150c8929d4e Mon Sep 17 00:00:00 2001
From: barneygale <barney.gale@gmail.com>
Date: Fri, 12 Apr 2024 22:24:05 +0100
Subject: [PATCH 2/2] Remove errant newline

---
 Lib/pathlib/__init__.py | 1 -
 1 file changed, 1 deletion(-)

diff --git a/Lib/pathlib/__init__.py b/Lib/pathlib/__init__.py
index 9a5bb2340f5de8..66eb08a45b1bb3 100644
--- a/Lib/pathlib/__init__.py
+++ b/Lib/pathlib/__init__.py
@@ -591,7 +591,6 @@ def iterdir(self):
             paths = map(self._remove_leading_dot, paths)
         return map(self._from_parsed_string, paths)
 
-
     def glob(self, pattern, *, case_sensitive=None, recurse_symlinks=False):
         """Iterate over this subtree and yield all existing files (of any
         kind, including directories) matching the given relative pattern.