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gh-151788: Speed up http.server directory listing by using os.scandir() #151789

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gh-151788: Speed up http.server directory listing by using os.scandir() #151789

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0606d02
gh-151788: Speed up http.server directory listing by using os.scandir
mjbommar Jun 20, 2026
9ba9f68
gh-151788: Address review — OSError fallback and tone down NEWS
mjbommar Jun 20, 2026
57bc982
gh-151788: Address review — drop perf comment, tame NEWS wording
mjbommar Jun 20, 2026
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24 changes: 17 additions & 7 deletions Lib/http/server.py
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Original file line number Diff line number Diff line change
Expand Up @@ -872,13 +872,13 @@ def list_directory(self, path):

"""
try:
list = os.listdir(path)
with os.scandir(path) as it:
entries = sorted(it, key=lambda e: e.name.lower())
except OSError:
self.send_error(
HTTPStatus.NOT_FOUND,
"No permission to list directory")
return None
list.sort(key=lambda a: a.lower())
r = []
displaypath = self.path
displaypath = displaypath.split('#', 1)[0]
Expand All @@ -899,14 +899,24 @@ def list_directory(self, path):
r.append(f'<title>{title}</title>\n</head>')
r.append(f'<body>\n<h1>{title}</h1>')
r.append('<hr>\n<ul>')
for name in list:
fullname = os.path.join(path, name)
for entry in entries:
name = entry.name
displayname = linkname = name
# Append / for directories or @ for symbolic links
if os.path.isdir(fullname):
# Append / for directories or @ for symbolic links. is_dir() and
# is_symlink() can raise OSError where os.path.isdir()/islink()
# return False, so fall back to False to keep the same behavior.
try:
is_dir = entry.is_dir()
except OSError:
is_dir = False
try:
is_symlink = entry.is_symlink()
except OSError:
is_symlink = False
if is_dir:
displayname = name + "/"
linkname = name + "/"
if os.path.islink(fullname):
if is_symlink:
displayname = name + "@"
# Note: a link to a directory displays with @ and links with /
r.append('<li><a href="%s">%s</a></li>'
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5 changes: 5 additions & 0 deletions Misc/NEWS.d/next/Library/2026-06-20-09-00-26.gh-issue-151788.Gr8IxK.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1,5 @@
:class:`http.server.SimpleHTTPRequestHandler` now uses :func:`os.scandir`
instead of :func:`os.listdir` to build directory listings, avoiding an
:func:`os.stat` call per entry. This can improve
:meth:`~http.server.SimpleHTTPRequestHandler.list_directory` performance where
``stat`` calls are slow.
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