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Merged
merged 4 commits into from
Feb 17, 2025
Merged

gh-118761: Improve import time of cmd module #130056

merged 4 commits into from
Feb 17, 2025

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donBarbos
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@donBarbos donBarbos commented Feb 12, 2025 •
edited by bedevere-app bot
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I use lazy import for inspect module (called 1 time).
And I suggest getting rid of import string. This will improve import time as much as possible (benchmarks without string module separately in second comment).

CPython configure flags:

./configure --enable-optimizations --with-lto --enable-loadable-sqlite-extensions

Benchmarks:

Running: pipx install tuna && ./python -X importtime -c 'import cmd' 2> import.log && tuna import.log

Total import time: 0.023s -> 0.013s = x1.77 as fast

main branch PR branch
Screenshot from 2025-02-13 01-59-59 Screenshot from 2025-02-13 01-54-43

cmd import time: 0.016s -> 0.007s = x2.29 as fast

main branch PR branch
Screenshot from 2025-02-13 02-00-06 Screenshot from 2025-02-13 01-54-50

hyperfine: 23.7ms -> 15.0ms = x1.58 as fast

Main branch:

$ hyperfine --warmup 11 "./python -c 'import cmd'"
Benchmark 1: ./python -c 'import cmd'
  Time (mean ± σ):      23.7 ms ±   0.3 ms    [User: 20.3 ms, System: 3.3 ms]
  Range (min … max):    23.1 ms …  25.7 ms    123 runs

PR branch:

$ hyperfine --warmup 11 "./python -c 'import cmd'"
Benchmark 1: ./python -c 'import cmd'
  Time (mean ± σ):      15.0 ms ±   0.3 ms    [User: 12.6 ms, System: 2.4 ms]
  Range (min … max):    14.4 ms …  16.0 ms    189 runs

@bedevere-app bedevere-app bot mentioned this pull request Feb 12, 2025
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@donBarbos
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I also suggest removing import string and making the following one change:

# from this:
IDENTCHARS = string.ascii_letters + string.digits + '_'
# to this:
IDENTCHARS = ('ABCDEFGHIJKLMNOPQRSTUVWXYZ'
              'abcdefghijklmnopqrstuvwxyz'
              '0123456789'
              '_')

That's all!

Benchmarks for cmd module without import string

comparing with the main branch here are the results:

Total import time: 0.023s -> 0.008s = x2.88 as fast

main branch PR branch
Screenshot from 2025-02-13 01-59-59 Screenshot from 2025-02-13 01-53-26

cmd import time: 0.016s -> 0.001s = x16 as fast (or more :)

main branch PR branch
Screenshot from 2025-02-13 02-00-06 Screenshot from 2025-02-13 01-53-34

hyperfine: 23.7ms -> 9.0ms = x2.64 as fast

$ hyperfine --warmup 11 "./python -c 'import cmd'"
Benchmark 1: ./python -c 'import cmd'
  Time (mean ± σ):       9.0 ms ±   0.6 ms    [User: 7.6 ms, System: 1.4 ms]
  Range (min … max):     8.4 ms …  13.0 ms    288 runs

@gpshead
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gpshead commented Feb 17, 2025

Go ahead and remove the import string as described.

@donBarbos donBarbos requested a review from gpshead February 17, 2025 19:39
@gpshead gpshead enabled auto-merge (squash) February 17, 2025 20:03
@gpshead gpshead merged commit 99d9656 into python:main Feb 17, 2025
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@donBarbos @gpshead