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gh-117431: Improve performance of startswith, endswith, count and find methods for strings and bytes #117432

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gh-117431: Improve performance of startswith, endswith, count and find methods for strings and bytes #117432

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@eendebakpt eendebakpt commented Apr 1, 2024 •
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Benchmarks (non-PGO):

main: python -m timeit -s "s = 'abcdef'" "s.startswith('abc')"
5000000 loops, best of 5: 63.8 nsec per loop

pr: python -m timeit -s "s = 'abcdef'" "s.startswith('abc')"
5000000 loops, best of 5: 42.3 nsec per loop

main: python -m timeit -s "s = 'abcdef'" "s.count('a')"
5000000 loops, best of 5: 70 nsec per loop

pr: python -m timeit -s "s = 'abcdef'" "s.count('a')"
5000000 loops, best of 5: 51.4 nsec per loop

main: python -m timeit -s "s = b'abcdef'" "s.startswith(b'q')"
5000000 loops, best of 5: 68.3 nsec per loop

pr: python -m timeit -s "s = b'abcdef'" "s.startswith(b'q')"
5000000 loops, best of 5: 44.5 nsec per loop

Notes:

  • We could also add a fast path for the case where there are 2 or 3 arguments. Since all arguments are positional only, for 1, 2 or 3 arguments the parsing cannot fail. That will increase performance for the 2 and 3 argument case, but it adds some more complexity.

@bedevere-app bedevere-app bot mentioned this pull request Apr 1, 2024
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@eendebakpt eendebakpt marked this pull request as draft April 1, 2024 20:19
@eendebakpt eendebakpt changed the title Draft: gh-117431 Improve performance of startswith, endswith, count and find methods for strings and bytes gh-117431 Improve performance of startswith, endswith, count and find methods for strings and bytes Apr 1, 2024
@eendebakpt eendebakpt marked this pull request as ready for review April 1, 2024 21:16
@AlexWaygood AlexWaygood added the performance Performance or resource usage label Apr 1, 2024
@AlexWaygood AlexWaygood requested a review from gvanrossum April 2, 2024 14:38
@erlend-aasland erlend-aasland changed the title gh-117431 Improve performance of startswith, endswith, count and find methods for strings and bytes gh-117431: Improve performance of startswith, endswith, count and find methods for strings and bytes Apr 2, 2024
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Closing in favor of #117466

@eendebakpt eendebakpt closed this Apr 2, 2024
@eendebakpt eendebakpt deleted the parse_args_finds branch June 26, 2025 13:45
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