[Python-checkins] gh-95865: Further reduce quote_from_bytes memory consumption (#96860)

[gpshead]

https://github.com/python/cpython/commit/e61ca2243163d829ab04d91d8e67940ea850aefa
commit: e61ca2243163d829ab04d91d8e67940ea850aefa
branch: main
author: Gregory P. Smith <greg at krypto.org>
committer: gpshead <greg at krypto.org>
date: 2022-09-19T16:06:25-07:00
summary:

gh-95865: Further reduce quote_from_bytes memory consumption (#96860)

on large input values.  Based on Dennis Sweeney's chunking idea.

files:
A Misc/NEWS.d/next/Library/2022-09-16-07-53-29.gh-issue-95865.oHjX0A.rst
M Lib/test/test_urlparse.py
M Lib/urllib/parse.py

diff --git a/Lib/test/test_urlparse.py b/Lib/test/test_urlparse.py
index 2f629c72ae78..81d6018bd1a4 100644
--- a/Lib/test/test_urlparse.py
+++ b/Lib/test/test_urlparse.py
@@ -985,6 +985,10 @@ def test_quote_from_bytes(self):
         self.assertEqual(result, 'archaeological%20arcana')
         result = urllib.parse.quote_from_bytes(b'')
         self.assertEqual(result, '')
+        result = urllib.parse.quote_from_bytes(b'A'*10_000)
+        self.assertEqual(result, 'A'*10_000)
+        result = urllib.parse.quote_from_bytes(b'z\x01/ '*253_183)
+        self.assertEqual(result, 'z%01/%20'*253_183)
 
     def test_unquote_to_bytes(self):
         result = urllib.parse.unquote_to_bytes('abc%20def')
diff --git a/Lib/urllib/parse.py b/Lib/urllib/parse.py
index f25c770068bd..3734c73948c6 100644
--- a/Lib/urllib/parse.py
+++ b/Lib/urllib/parse.py
@@ -29,6 +29,7 @@
 
 from collections import namedtuple
 import functools
+import math
 import re
 import types
 import warnings
@@ -906,7 +907,14 @@ def quote_from_bytes(bs, safe='/'):
     if not bs.rstrip(_ALWAYS_SAFE_BYTES + safe):
         return bs.decode()
     quoter = _byte_quoter_factory(safe)
-    return ''.join(map(quoter, bs))
+    if (bs_len := len(bs)) < 200_000:
+        return ''.join(map(quoter, bs))
+    else:
+        # This saves memory - https://github.com/python/cpython/issues/95865
+        chunk_size = math.isqrt(bs_len)
+        chunks = [''.join(map(quoter, bs[i:i+chunk_size]))
+                  for i in range(0, bs_len, chunk_size)]
+        return ''.join(chunks)
 
 def urlencode(query, doseq=False, safe='', encoding=None, errors=None,
               quote_via=quote_plus):
diff --git a/Misc/NEWS.d/next/Library/2022-09-16-07-53-29.gh-issue-95865.oHjX0A.rst b/Misc/NEWS.d/next/Library/2022-09-16-07-53-29.gh-issue-95865.oHjX0A.rst
new file mode 100644
index 000000000000..03a5be722949
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2022-09-16-07-53-29.gh-issue-95865.oHjX0A.rst
@@ -0,0 +1,3 @@
+Reduce :func:`urllib.parse.quote_from_bytes` memory use on large values.
+
+Contributed by Dennis Sweeney.