8000 GH-120754: Disable buffering in Path.read_bytes by cmaloney · Pull Request #122111 · python/cpython · GitHub
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GH-120754: Disable buffering in Path.read_bytes #122111

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Merged
merged 2 commits into from
Aug 16, 2024
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GH-120754: Disable buffering in Path.read_bytes #122111

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dac5dd9
GH-120754: Disable buffering in Path.read_bytes
cmaloney Jul 22, 2024
02eaa92
📜🤖 Added by blurb_it.
blurb-it[bot] Jul 22, 2024
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GH-120754: Disable buffering in Path.read_bytes 
`Path.read_bytes()` is used to read a whole file. buffering /
BufferedIO is focused around making small, possibly interleaved,
read/write efficient which doesn't add value in this case.

On my Mac, running the benchmark:

```python
import pyperf
from pathlib import Path

def read_all(all_paths):
    for p in all_paths:
        p.read_bytes()

def read_file(path_obj):
    path_obj.read_bytes()

all_rst = list(Path("Doc").glob("**/*.rst"))
all_py = list(Path(".").glob("**/*.py"))
assert all_rst, "Should have found rst files"
assert all_py, "Should have found python source files"

runner = pyperf.Runner()
runner.bench_func("read_file_small", read_file, Path("Doc/howto/clinic.rst"))
runner.bench_func("read_file_large", read_file, Path("Doc/c-api/typeobj.rst"))
```

before:
```python
.....................
read_file_small: Mean +- std dev: 6.80 us +- 0.07 us
.....................
read_file_large: Mean +- std dev: 10.8 us +- 0.2 us
````

after:
```python
.....................
read_file_small: Mean +- std dev: 5.67 us +- 0.05 us
.....................
read_file_large: Mean +- std dev: 9.77 us +- 0.52 us
```
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@cmaloney
cmaloney committed Jul 22, 2024
commit dac5dd9f15f960f808a9bd547fa4271db6478b5e
2 changes: 1 addition & 1 deletion Lib/pathlib/_abc.py
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Original file line number Diff line number Diff line change
Expand Up @@ -576,7 +576,7 @@ def read_bytes(self):
"""
Open the file in bytes mode, read it, and close the file.
"""
with self.open(mode='rb') as f:
with self.open(mode='rb', buffering=0) as f:
return f.read()

def read_text(self, encoding=None, errors=None, newline=None):
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2 changes: 1 addition & 1 deletion Lib/test/test_pathlib/test_pathlib_abc.py
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Expand Up @@ -1465,7 +1465,7 @@ def stat(self, *, follow_symlinks=True):

def open(self, mode='r', buffering=-1, encoding=None,
errors=None, newline=None):
if buffering != -1:
if buffering != -1 and not (buffering == 0 and 'b' in mode):
raise NotImplementedError
path_obj = self.resolve()
path = str(path_obj)
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