`_colorize` module is slow to import, affecting `traceback` and `logging` modules

“It is a truth universally acknowledged, that a module in possession of great colors, suffers import time slowdown.

_colorize module is slow to import due to its use of dataclasses

python -Ximporttime -c "import _colorize"

Visualization in tuna

Notice that significant time is also spent executing the _colorize, due to the creation of its dataclasses

❯ uvx python@3.15 -m cProfile -m _colorize | head -15
         5609 function calls (5489 primitive calls) in 0.006 seconds

   Ordered by: cumulative time

   ncalls  tottime  percall  cumtime  percall filename:lineno(function)
      9/1    0.003    0.000    0.006    0.006 {built-in method builtins.exec}
        1    0.000    0.000    0.006    0.006 <string>:1(<module>)
        1    0.000    0.000    0.006    0.006 <frozen runpy>:199(run_module)
        1    0.000    0.000    0.006    0.006 <frozen runpy>:65(_run_code)
        1    0.000    0.000    0.006    0.006 _colorize.py:1(<module>)
        7    0.000    0.000    0.005    0.001 dataclasses.py:1432(wrap)
        7    0.000    0.000    0.005    0.001 dataclasses.py:986(_process_class)
        7    0.000    0.000    0.003    0.000 dataclasses.py:478(add_fns_to_class)
        4    0.000    0.000    0.001    0.000 inspect.py:3342(signature)
        4    0.000    0.000    0.001    0.000 inspect.py:3055(from_callable)

The slow import time directly affects (among others) the traceback module which in turn affects logging, which is 40% slower in 3.14 and 3.15 compared to 3.13. That is quite unfortunate since in applications that care about import time, logging module is typically hard to avoid (I originally discovered this when looking at pip's startup time)

 hyperfine -w 10 "python3.13 -c 'import logging'"  "python3.15 -c 'import logging'" 
Benchmark 1: python3.13 -c 'import logging'
  Time (mean ± σ):      21.0 ms ±   3.4 ms    [User: 14.8 ms, System: 5.9 ms]
  Range (min … max):    16.2 ms …  28.2 ms    155 runs
 
Benchmark 2: python3.15 -c 'import logging'
  Time (mean ± σ):      29.6 ms ±   2.1 ms    [User: 22.2 ms, System: 7.0 ms]
  Range (min … max):    26.4 ms …  35.1 ms    100 runs
 
Summary
  python3.13 -c 'import logging' ran
    1.40 ± 0.25 times faster than /home/hollas/.local/share/uv/python/cpython-3.15.0a5-linux-x86_64-gnu/bin/python3.15 -c 'import logging'

It's not very clear how to make this better (besides not using dataclasses). We tried to make traceback lazy in logging, but failed. #112995

Linked PRs

• gh-144879
• gh-149318

Inizia con il modulo _colorize e riproduci il relativo profilo di importazione usando python -Ximporttime -c "import _colorize" e il comando cProfile mostrato. Confronta i benchmark di logging, quindi esamina le PR collegate gh-144879 e gh-149318; il lavoro è completato quando viene ridotto l’overhead di importazione che interessa _colorize, traceback e logging.