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gh-129813, PEP 782: Use PyBytesWriter in bytes_concat() #138840

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gh-129813, PEP 782: Use PyBytesWriter in bytes_concat() #138840

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@vstinner vstinner commented Sep 12, 2025 •
edited by bedevere-app bot
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Replace PyBytes_FromStringAndSize(NULL, size) with the new public PyBytesWriter API.

@vstinner
pythongh-129813, PEP 782: Use PyBytesWriter in bytes_concat()
3bded64 
Replace PyBytes_FromStringAndSize(NULL, size) with the new public
PyBytesWriter API.
@bedevere-app bedevere-app bot mentioned this pull request Sep 12, 2025
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Microbenchmark on bytes + bytes:

python -m pyperf timeit -s 'a=b"a"; b=b"b"' 'a+b'

Result: Mean +- std dev: [ref] 38.0 ns +- 1.1 ns -> [pep782] 52.7 ns +- 1.7 ns: 1.39x slower.

Oh, this change has a significant impact on performance. I prefer to abandon it.

@vstinner vstinner closed this Sep 13, 2025
@vstinner vstinner deleted the pybyteswriter_bytes_concat branch September 13, 2025 17:05
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