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bpo-37348: optimize decoding ASCII string #14283

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merged 7 commits into from Jun 24, 2019
Merged

bpo-37348: optimize decoding ASCII string #14283

merged 7 commits into from Jun 24, 2019

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methane commented Jun 21, 2019 •
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Use _PyUnicode_Writer only after ascii_decode is failed.

https://bugs.python.org/issue37348

methane mentioned this pull request Jun 21, 2019
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brettcannon added the performance Performance or resource usage label Jun 21, 2019
vstinner reviewed Jun 21, 2019
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methane commented Jun 22, 2019 

$ ./python -m pyperf timeit --compare-to=./python-master -s 'b=b"foo"' -- 'b.decode()'
python-master: ..................... 83.3 ns +- 1.2 ns
python: ..................... 72.4 ns +- 1.1 ns

Mean +- std dev: [python-master] 83.3 ns +- 1.2 ns -> [python] 72.4 ns +- 1.1 ns: 1.15x faster (-13%)

PyUnicode_FromString("aaaaaaaaaaaaaaaaaaaaaaaaaaaaaa");: about 38ns -> 28ns

methane merged commit 770847a into python:master Jun 24, 2019
methane deleted the ascii-fromstring branch Jun 24, 2019
lisroach pushed a commit to lisroach/cpython that referenced this pull request Sep 10, 2019
bpo-37348: optimize decoding ASCII string (pythonGH-14283)
6634958 
`_PyUnicode_Writer` is a relatively complex structure.  Initializing it is significant overhead when decoding short ASCII string.
DinoV pushed a commit to DinoV/cpython that referenced this pull request Jan 14, 2020
bpo-37348: optimize decoding ASCII string (pythonGH-14283)
04efd0d 
`_PyUnicode_Writer` is a relatively complex structure.  Initializing it is significant overhead when decoding short ASCII string.
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