https://github.com/python/cpython/commit/58f3fe0d9b9882656e629e8caab687c7fcb21b36
commit: 58f3fe0d9b9882656e629e8caab687c7fcb21b36
branch: main
author: Cody Maloney <[email protected]>
committer: vstinner <[email protected]>
date: 2025-11-18T10:10:32+01:00
summary:
gh-129005: Remove copies from _pyio using take_bytes (#141539)
Memory usage now matches that of _io for large files.
files:
M Lib/_pyio.py
M Lib/test/test_io/test_bufferedio.py
M Lib/test/test_io/test_largefile.py
diff --git a/Lib/_pyio.py b/Lib/_pyio.py
index 423178e87a8684..69a088df8fc987 100644
--- a/Lib/_pyio.py
+++ b/Lib/_pyio.py
@@ -546,7 +546,7 @@ def nreadahead():
res += b
if res.endswith(b"\n"):
break
- return bytes(res)
+ return res.take_bytes()
def __iter__(self):
self._checkClosed()
@@ -620,7 +620,7 @@ def read(self, size=-1):
if n < 0 or n > len(b):
raise ValueError(f"readinto returned {n} outside buffer size
{len(b)}")
del b[n:]
- return bytes(b)
+ return b.take_bytes()
def readall(self):
"""Read until EOF, using multiple read() call."""
@@ -628,7 +628,7 @@ def readall(self):
while data := self.read(DEFAULT_BUFFER_SIZE):
res += data
if res:
- return bytes(res)
+ return res.take_bytes()
else:
# b'' or None
return data
@@ -1738,7 +1738,7 @@ def readall(self):
assert len(result) - bytes_read >= 1, \
"os.readinto buffer size 0 will result in erroneous EOF / returns
0"
result.resize(bytes_read)
- return bytes(result)
+ return result.take_bytes()
def readinto(self, buffer):
"""Same as RawIOBase.readinto()."""
diff --git a/Lib/test/test_io/test_bufferedio.py
b/Lib/test/test_io/test_bufferedio.py
index 30c34e818b1572..3278665bdc9dd3 100644
--- a/Lib/test/test_io/test_bufferedio.py
+++ b/Lib/test/test_io/test_bufferedio.py
@@ -1277,7 +1277,8 @@ def test_flush_and_readinto(self):
def _readinto(bufio, n=-1):
b = bytearray(n if n >= 0 else 9999)
n = bufio.readinto(b)
- return bytes(b[:n])
+ b.resize(n)
+ return b.take_bytes()
self.check_flush_and_read(_readinto)
def test_flush_and_peek(self):
diff --git a/Lib/test/test_io/test_largefile.py
b/Lib/test/test_io/test_largefile.py
index 41f7b70e5cfe81..438a90a92ed588 100644
--- a/Lib/test/test_io/test_largefile.py
+++ b/Lib/test/test_io/test_largefile.py
@@ -56,9 +56,7 @@ class TestFileMethods(LargeFileTest):
(i.e. > 2 GiB) files.
"""
- # _pyio.FileIO.readall() uses a temporary bytearray then casted to bytes,
- # so memuse=2 is needed
- @bigmemtest(size=size, memuse=2, dry_run=False)
+ @bigmemtest(size=size, memuse=1, dry_run=False)
def test_large_read(self, _size):
# bpo-24658: Test that a read greater than 2GB does not fail.
with self.open(TESTFN, "rb") as f:
@@ -154,7 +152,7 @@ def test_seekable(self):
f.seek(pos)
self.assertTrue(f.seekable())
- @bigmemtest(size=size, memuse=2, dry_run=False)
+ @bigmemtest(size=size, memuse=1, dry_run=False)
def test_seek_readall(self, _size):
# Seek which doesn't change position should readall successfully.
with self.open(TESTFN, 'rb') as f:
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