GH-120754: Disable buffering in Path.read_bytes #122111
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`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
```
hauntsaninja
approved these changes
Aug 16, 2024
jeremyhylton
pushed a commit
to jeremyhylton/cpython
that referenced
this pull request
Aug 19, 2024
`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
```
blhsing
pushed a commit
to blhsing/cpython
that referenced
this pull request
Aug 22, 2024
`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
```
cmaloney
added a commit
to cmaloney/cpython
that referenced
this pull request
Aug 28, 2024
NOTE: This needs a full buildbot test pass before merge, see: python#121143 (comment). 1. Added `statx` to set of allowed syscall forms (Should make Raspian bot pass). 2. Check that the `fd` returned from `open` is passed to all future calls. This helps ensure things like the `stat` call uses the file descriptor rather than the `filename` to avoid TOCTOU isuses. 3. Update the `Path().read_bytes()` test case to additionally validate the reduction in`isatty`/`ioctl` + `seek` calls from python#122111 4. Better diagnostic assertion messagess from @gpshead, so when the test fails have first information immediately available. Makes remote CI debugging much simpler.
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Path.read_bytes()is used to read a whole file.buffering=/BufferedIOis focused around making small, possibly interleaved, read and write efficient which doesn't add value for this case. This makesseek+isattysystem call no longer called in this case, as well as removing the construction of the BufferedIO, allocation of a buffer, etc.Benchmark
Run on my Mac
Benchmark code
Before:
After: