perflint

library0.8.1pypypiunverified

Perflint is an extension for Pylint that identifies performance anti-patterns in Python code, helping developers optimize their applications by flagging common inefficiencies. It is currently in early beta, version 0.8.1, and may produce false positives. The project is actively maintained with a focus on enhancing code performance through static analysis.

testing

pip install perflint

github ↗package ↗

INSTALL

IMPORT

SIG · PERFLINT

perflint

testingpythonv0.8.1

Install

2.7s avg

Import

—

Disk

26MB

Pass rate

10/ 10

Env Coverage10 / 10

glibc

3.9–3.13

musl

3.9–3.13

Install & Compatibility

Where this runs

tested against v0.8.1 · pip install

no network on importno background threads

Install × environment matrix

Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux

musl

py 3.10–3.910 runs

installs and imports cleanly · install 0.0s · import 0.000s · 26.9MB

glibc

py 3.10–3.910 runs

installs and imports cleanly · install 2.7s · import 0.000s · 27MB

26MB installed

● package 26MB

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

Perflint as Pylint Plugin

✓ pylint your_module/ --load-plugins=perflint

✗ from perflint import some_check

Perflint is not imported as a Python module in application code. It's loaded as a plugin for Pylint via the command line or configuration.

Save the code above as `my_module.py`. Then run Perflint as a Pylint plugin. It will highlight performance anti-patterns like global lookups in loops, unnecessary list casting, and inefficient dictionary iteration.

import os def process_data(items): # W8202: Global name usage in a loop # os.environ is a global lookup; cache it outside the loop for performance. for item in items: value = os.environ.get(item, 'default') # This will trigger W8202 print(value) def unnecessary_list_cast_example(data): # W8101: Unnecessary use of list() on an already iterable type for x in list(data): # data is already iterable, no need for list() print(x) def incorrect_dict_iterator_example(dictionary): # W8102: Incorrect iterator method for dict for _, value in dictionary.items(): # If only values are needed, use .values() print(value) if __name__ == '__main__': my_items = ['HOME', 'PATH'] process_data(my_items) my_tuple = (1, 2, 3) unnecessary_list_cast_example(my_tuple) my_dict = {'a': 1, 'b': 2} incorrect_dict_iterator_example(my_dict)

Debug

Known issues

gotchaPerflint is currently an 'early beta' and may generate false positives, requiring careful review of its findings.

fix

Always manually verify reported performance anti-patterns before refactoring code based on Perflint warnings.

affects: 0.1.0 - 0.8.1

breakingUsing `try...except` blocks inside loops can have significant computational overhead, especially in Python versions prior to 3.11 (R8203).

fix

Refactor code to place the entire loop within a single `try` block, or move exception handling outside the loop if possible, to avoid per-iteration overhead.

affects: <=3.10

gotchaDotted imports (e.g., `os.path.exists`) inside loops can be inefficient because Python performs multiple lookups in each iteration (W8205).

fix

Import the specific function or attribute directly before the loop (e.g., `from os.path import exists`) to reduce lookup overhead.

affects: All versions

gotchaAccessing global variables within a tight loop can be slower than using local variables (W8202).

fix

Cache the global variable's value in a local variable outside the loop, then use the local variable inside the loop.

affects: All versions

Upgrade

Version history

0.8.1latest on PyPI · released Jan 10, 2024

Audit

Dependencies

pylintrequiredPerflint functions as a plugin for Pylint.

Agent activity

2 hits · last 30 days

node

Resources

githubhttps://github.com/tonybaloney/perflint ↗

packagehttps://pypi.org/project/perflint/ ↗