[Python-Dev] PEP 563: Postponed Evaluation of Annotations (original) (raw)

Barry Warsaw barry at python.org
Fri Nov 3 16:44:59 EDT 2017

On Nov 2, 2017, at 23:22, Nick Coghlan <ncoghlan at gmail.com> wrote:

Another point worth noting is that merely importing the typing module is expensive:

$ python -m perf timeit -s "from importlib import reload; import typing" "reload(typing)" ..................... Mean +- std dev: 10.6 ms +- 0.6 ms 10 ms is a big chunk out of a CLI application's startup time budget.

Far and away so, except for the re module.

% ./python.exe -X importtime -c "import typing" import time: self [us] | cumulative | imported package import time: 72 | 72 | _codecs import time: 625 | 696 | codecs import time: 354 | 354 | encodings.aliases import time: 713 | 1762 | encodings import time: 198 | 198 | encodings.utf_8 import time: 98 | 98 | _signal import time: 233 | 233 | encodings.latin_1 import time: 353 | 353 | _weakrefset import time: 264 | 617 | abc import time: 402 | 1018 | io import time: 136 | 136 | _stat import time: 197 | 333 | stat import time: 227 | 227 | genericpath import time: 377 | 604 | posixpath import time: 2812 | 2812 | _collections_abc import time: 787 | 4534 | os import time: 315 | 315 | _sitebuiltins import time: 336 | 336 | sitecustomize import time: 114 | 114 | usercustomize import time: 1064 | 6361 | site import time: 160 | 160 | _operator import time: 1412 | 1571 | operator import time: 371 | 371 | keyword import time: 817 | 817 | _heapq import time: 762 | 1579 | heapq import time: 272 | 272 | itertools import time: 635 | 635 | reprlib import time: 99 | 99 | _collections import time: 3580 | 8104 | collections import time: 112 | 112 | _functools import time: 781 | 892 | functools import time: 1774 | 2666 | contextlib import time: 272 | 272 | types import time: 861 | 1132 | enum import time: 76 | 76 | _sre import time: 426 | 426 | sre_constants import time: 446 | 872 | sre_parse import time: 414 | 1361 | sre_compile import time: 79 | 79 | _locale import time: 190 | 190 | copyreg import time: 17200 | 19961 | re import time: 374 | 374 | collections.abc import time: 15124 | 46226 | typing

-Barry

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