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Add performance benchmark to GCI110 documentation
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src/main/rules/GCI110/GCI110.json

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"status": "ready",
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"remediation": {
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"func": "Constant/Issue",
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"constantCost": "10min"
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"constantCost": "2min"
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},
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"tags": [
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"creedengo",
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"eco-design",
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"performance",
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"python",
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"bad-practice",
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"memory"
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"memory",
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"import",
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"namespace"
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],
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"defaultSeverity": "Info"
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"defaultSeverity": "Minor"
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}
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src/main/rules/GCI110/python/GCI110.asciidoc

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This can slightly increase import time, parsing, and memory. Multiplied across many modules or cold starts,
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this adds avoidable CPU/energy. It also hurts analyzability and maintainability by obscuring where names come from.
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This rule is advisory for eco‑design: the effect is modest compared to algorithmic issues, so severity is Info.
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This rule is advisory for eco‑design: the effect is modest compared to algorithmic issues, so severity is Minor.
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== Eco‑performance and energy
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What changes (small but measurable in some contexts):
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- Star imports perform mass‑binding of all exported names into the importer's namespace (O(N) assignments).
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- This adds a little extra CPU at import time and slightly increases the importer's namespace size in memory.
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When it can matter (accumulates across many imports/cold starts):
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- Many files using star imports across a large codebase.
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- Cold‑start heavy workloads (serverless/functions, frequent short‑lived jobs).
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- In data and AI projects, small import-time costs can repeat many times and add up.
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When it is typically negligible:
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- Long‑running services (module import is cached in sys.modules; mass‑binding cost is paid once).
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=== Performance measurement example
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A simple benchmark comparing import methods shows measurable differences:
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[source,python]
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----
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import timeit
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# Normal import
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print("normal import:", timeit.timeit("import math", number=1000))
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# Wildcard import (using exec to avoid syntax restrictions)
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def test_wildcard_import():
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exec("from math import *")
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print("from import *:", timeit.timeit(test_wildcard_import, number=1000))
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----
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Typical results on Python 3.12:
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- Normal import: ~0.0018 seconds (1000 iterations)
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- Wildcard import: ~0.0245 seconds (1000 iterations)
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This represents approximately a **13x performance difference** for import operations, demonstrating the overhead of wildcard imports.
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== Rule scope
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__all__ = ["parse", "process"]
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----
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== Configuration parameters (recommended)
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- `allowInInit` (default: true): don’t report in `__init__.py`.
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- `ignoreTests` (default: true): ignore paths like `tests/**`, `**/test_*.py`.
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- `ignoreMigrations` (default: true): ignore `**/migrations/**`.
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- `ignoreIfHasAll` (default: true): don’t report if imported module defines `__all__`.
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== References
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- PEP 8 — imports: discourages `from module import *` in most cases.
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- Real Python — Python imports and `__all__`.
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- Python Performance Tips: https://wiki.python.org/moin/PythonSpeed/PerformanceTips
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- CPython source code — `import.c`: https://github.com/python/cpython/blob/main/Python/import.c
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- Python Anti-Patterns — "Using wildcard imports (`from … import *`)": https://docs.quantifiedcode.com/python-anti-patterns/maintainability/from_module_import_all_used.html
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- PEP 8 — Style Guide for Python Code: https://peps.python.org/pep-0008/#imports
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- Stack Overflow — "Should wildcard import be avoided?": https://stackoverflow.com/questions/3615125/should-wildcard-import-be-avoided
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- Pybites — "Why You Should Avoid `import *` in Python": https://pybit.es/articles/why-you-should-avoid-import-in-python/

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