Jonas H. <[email protected]> added the comment:
I agree with your statement in principle. Here are numbers for the slowdown
that's introduced:
Without the change:
./python.exe -m timeit -s 'import re'\n'[re.compile(f"fill_cache{i}") for i
in range(512)]'\n'pat = re.compile(".")' 're.match(pat, "asdf")'
500000 loops, best of 5: 462 nsec per loop
./python.exe -m timeit -s 'import re'\n'[re.compile(f"fill_cache{i}") for i
in range(512)]'\n'pat = re.compile(".")' 're.match(".", "asdf")'
1000000 loops, best of 5: 316 nsec per loop
With the change:
./python.exe -m timeit -s 'import re'\n'[re.compile(f"fill_cache{i}") for i
in range(512)]'\n'pat = re.compile(".")' 're.match(pat, "asdf")'
1000000 loops, best of 5: 207 nsec per loop
./python.exe -m timeit -s 'import re'\n'[re.compile(f"fill_cache{i}") for i
in range(512)]'\n'pat = re.compile(".")' 're.match(".", "asdf")'
1000000 loops, best of 5: 351 nsec per loop
So we have a 2x speedup in the uncommon case and a 10% slowdown in the common
case.
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<https://bugs.python.org/issue45462>
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