step3: profit

A small, focused Python profiler built on sys.monitoring (Python 3.12+).

Installation

uv tool install step3  # recommended

Or run without installing:

uvx --from step3 profit

Or with pip: pip install step3

Usage

profit run — profile a script

profit run script.py

Focus on specific functions:

profit run script.py -p mymod:func1 -p mymod:func2

Compare two functions side by side:

profit run script.py -b mymod:func_old -p mymod:func_new

Run a module:

profit run -m mypackage.module

Pass arguments to the script after --:

profit run script.py -- --script-arg value

Options

Targets use importable names: mymod:MyClass.method or mymod.func.

profit timeit — profile a statement in a loop

profit timeit 'sum(range(1000))'

With setup code:

profit timeit 'f()' --setup 'from mymod import f'

Focus on specific functions:

profit timeit 'f()' --setup 'from mymod import f' -p mymod:f

Options

Global options

Python API

Context manager — profile a block of code:

from step3 import profit

with profit as p:
    do_work()

p.print_stats()

Decorator — profile a specific function:

from step3 import profit

@profit
def my_func():
    ...

my_func()
profit.print_stats()

Requirements

• Python 3.12+