Defer imports for faster overall import time: 19 ms -> 5 ms

[hugovk]

Defer imports, especially avoid typing import for normal use, which is getting slower in 3.14, to make the overall import time of humanize faster.

Before: 19 ms

After: 5 ms

Also move mypy dependency to autoupdateable requirements file.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.48%. Comparing base (c6455cf) to head (147cbbc).
Report is 4 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #234      +/-   ##
==========================================
- Coverage   99.49%   99.48%   -0.01%     
==========================================
  Files          11       11              
  Lines         785      782       -3     
==========================================
- Hits          781      778       -3     
  Misses          4        4              

Flag	Coverage Δ
macos-latest	97.69% <100.00%> (-0.01%)	⬇️
ubuntu-latest	97.69% <100.00%> (-0.01%)	⬇️
windows-latest	95.90% <100.00%> (-0.02%)	⬇️

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[glensc]

@hugovk care to share how you measured those things and made graphs? I want to check similarly in my project.

[hugovk]

Sure!

Before each test I ran python3 -c 'import humanize' to make sure everything was cached after making source changes, so any pyc files had been created etc.

Then I ran python3 -X importtime -c "import humanize" 2> import.log. The log file looks like this, and shows each import time and the total:

import time: self [us] | cumulative | imported package
import time:       114 |        114 |   _io
import time:        18 |         18 |   marshal
import time:       146 |        146 |   posix
import time:       376 |        653 | _frozen_importlib_external
import time:       354 |        354 |   time
import time:       149 |        502 | zipimport
import time:        32 |         32 |     _codecs
import time:       363 |        394 |   codecs
import time:       273 |        273 |   encodings.aliases
import time:       475 |       1141 | encodings
import time:       108 |        108 | encodings.utf_8
import time:        49 |         49 | _signal
import time:        17 |         17 |     _abc
import time:       112 |        128 |   abc
import time:       108 |        236 | io
import time:        28 |         28 |       _stat
import time:        53 |         80 |     stat
import time:       491 |        491 |     _collections_abc
import time:        34 |         34 |       errno
import time:        36 |         36 |       genericpath
import time:        88 |        157 |     posixpath
import time:       308 |       1035 |   os
import time:        53 |         53 |   _sitebuiltins
import time:       128 |        128 |   encodings.utf_8_sig
import time:       296 |        296 |   types
import time:        93 |         93 |     importlib
import time:       121 |        121 |     importlib._abc
import time:       105 |        318 |   importlib.util
import time:        26 |         26 |   importlib.machinery
import time:       234 |        234 |   _distutils_hack
import time:        89 |         89 |     __future__
import time:       110 |        199 |   pre_commit_uv
import time:       452 |        452 |   sitecustomize
import time:        74 |         74 |   usercustomize
import time:      3351 |       6159 | site
import time:       132 |        132 | linecache
import time:        88 |         88 |   humanize.filesize
import time:        36 |         36 |         _operator
import time:       161 |        197 |       operator
import time:        62 |         62 |               itertools
import time:        85 |         85 |               keyword
import time:       112 |        112 |               reprlib
import time:        34 |         34 |               _collections
import time:       640 |        931 |             collections
import time:        63 |         63 |             _functools
import time:       395 |       1388 |           functools
import time:       803 |       2191 |         enum
import time:        56 |         56 |           _sre
import time:       145 |        145 |             re._constants
import time:       269 |        414 |           re._parser
import time:        65 |         65 |           re._casefix
import time:       284 |        817 |         re._compiler
import time:       130 |        130 |         copyreg
import time:       325 |       3462 |       re
import time:       626 |       4283 |     gettext
import time:       228 |        228 |       warnings
import time:       136 |        136 |       _weakrefset
import time:       394 |        758 |     threading
import time:        78 |       5118 |   humanize.i18n
import time:        68 |         68 |   humanize.lists
import time:       110 |        110 |   humanize.number
import time:       266 |        266 |   humanize.time
import time:        63 |         63 |   humanize._version
import time:       137 |       5847 | humanize

Rather than poring over the log file, you can install https://github.com/nschloe/tuna and run that on the log: tuna import.log

That opens the visualisation in the browser. It's a nice tool, you can click and zoom in to see the sub-imports, and click the top to zoom out again.

Then change your code to defer some imports and repeat :)

See also https://medium.com/alan/how-we-improved-our-python-backend-start-up-time-2c33cd4873c8

Another good tool is https://github.com/sharkdp/hyperfine, which repeatedly runs a command to get an average, for example:

❯ hyperfine --warmup 3 "python3 -c 'import humanize'"
Benchmark 1: python3 -c 'import humanize'
  Time (mean ± σ):      21.4 ms ±   0.7 ms    [User: 15.9 ms, System: 4.6 ms]
  Range (min … max):    20.2 ms …  24.1 ms    127 runs

More advanced use allows you to give it two commands and it'll compare them both. You can give different setup commands as well, like tell it to checkout a Git branch before each test. This is for broader use as it includes the Python interpreter startup overhead, whereas -X importtime is more focused.