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GeezerVison is showing github.com — gh-129813, PEP 782: Use PyBytesWriter in FileIO.read() by vstinner · Pull Request #138955 · python/cpython

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@vstinner

@vstinner vstinner commented Sep 15, 2025 •
edited by bedevere-app Bot
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Replace PyBytes_FromStringAndSize(NULL, size) and _PyBytes_Resize() with the new public PyBytesWriter API.

  • Issue: [C API] PEP 782: Add PyBytesWriter API #129813

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@vstinner
pythongh-129813, PEP 782: Use PyBytesWriter in FileIO.read()
aed84c9 
Replace PyBytes_FromStringAndSize(NULL, size) and _PyBytes_Resize()
with the new public PyBytesWriter API.
@vstinner vstinner added the skip news label Sep 15, 2025
@bedevere-app bedevere-app Bot added the awaiting core review label Sep 15, 2025
@bedevere-app bedevere-app Bot mentioned this pull request Sep 15, 2025
[C API] PEP 782: Add PyBytesWriter API #129813
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@vstinner

vstinner commented Sep 15, 2025

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Benchmark:

import pyperf
import os

file = open(__file__, "rb", 0)
def func():
    file.seek(0)
    for _ in range(100):
        file.read(1)

runner = pyperf.Runner()
runner.bench_func('bench', func)

file.close()

Result: Mean +- std dev: [ref] 65.8 us +- 1.0 us -> [change] 63.2 us +- 1.0 us: 1.04x faster

cc @cmaloney
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cmaloney
cmaloney approved these changes Sep 15, 2025
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@vstinner
vstinner merged commit e814e6b into python:main Sep 15, 2025
@vstinner
vstinner deleted the pybyteswriter_fileio branch September 15, 2025 21:49
@bedevere-app bedevere-app Bot removed the awaiting core review label Sep 15, 2025
@vstinner

vstinner commented Sep 15, 2025

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Merged. Thanks for the review @cmaloney.
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@cmaloney cmaloney cmaloney approved these changes

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@vstinner @cmaloney
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