timeit

Timeit is a Python standard library module for measuring the execution time of small code snippets. It focuses on accuracy and minimal overhead by repeatedly executing the target code and by isolating setup work, using a high-resolution timer. Time measurements produced are intended to help compare implementations or micro-optimize code rather than to benchmark long-running tasks.

The module provides two primary interfaces: a functional interface timeit.timeit and a Timer class. Both accept a code string to be run, an optional setup string, and an optional globals mapping to provide variables without re-importing in every run. The Timer can be configured with a custom timer function and can report the total time for a given number of executions via timeit(number=...). It also offers repeat(repeat, number) to obtain multiple timings. The default timer is typically time.perf_counter, which offers high-resolution wall-clock timing.

Usage example: timeit.timeit("sum(range(10))", setup="from itertools import accumulate", number=1000). Or using a Timer: t = timeit.Timer("sum(range(10))"); t.timeit(1000). For code that interacts with libraries, globals can be supplied to avoid repetitive setup.

Notes: For more stable results, disable garbage collection during timing and perform multiple repeats with a consistent number. The module also includes a command-line interface via python -m timeit to run statements directly from the shell.