Fantaisies programatico-ludiques

Handy recipe for timing Python code execution time

The timeit module is useful for micro benchmarks, but does not allow to measure execution time of large snippets, as it requires the code tested to fit in a string. Hence, I went looking for a context or decorator-based solution. And I found this bug report commented by Guido van Rossum, recommending a few recipes.

Here is another one, that can be used either as a decorator or as a "with-context", combining the following inspirations:

import gc
from contextlib import contextmanager
from functools import wraps
from time import perf_counter  # used by timeit module

def trace_exec_time(end_callback=None, **kwargs):
    def benchmark(**ctx_kwargs):
        gc_was_enabled = gc.isenabled()
        start = perf_counter()
        yield ctx_kwargs
        end = perf_counter()
        ctx_kwargs['exec_duration'] = end - start
        if end_callback:
        if gc_was_enabled:
    if end_callback:
        def decorator(func):
            def wrapper(*func_args, **func_kwargs):
                with benchmark(func_args=func_args, func_kwargs=func_kwargs,
                               func_name=func.__name__, **kwargs):
                    return func(*func_args, **func_kwargs)
            return wrapper
        return decorator
        return benchmark(**kwargs)

The triple args/kwargs variable shadowing is ugly, but that keeps the code short.

There are some usage examples:

def add(a, b):
    return a + b

add(2, b=3)  # -> {'func_kwargs': {'b': 3}, 'exec_duration': 1.9-06, 'func_args': (2,), 'func_name': 'add'}

with trace_exec_time(name='Heavy calculation') as report:
    result = big_compute(list_of_things)
print(report['name'], "%0.3fs" % report['exec_duration'])  # -> Heavy calculation 10.576s

[UPDATED] on 2016/08/04

With an aggregated list of all your timings, if you don't have numpy/scipy at hand, here is a handy recipe to compute some useful statistics out of them (requires Python 3 statistics module for pstdev):

import statistics

def compute_timing_stats(timings_in_ms):
    timings_in_ms = sorted(timings_in_ms)
    total = sum(timings_in_ms)
    return = {
        'count': len(timings_in_ms),
        'mean': total / len(timings_in_ms),
        'p00_min', timings_in_ms[0],
        'p01', percentile(timings_in_ms, 1),
        'p10', percentile(timings_in_ms, 10),
        'p50_median', percentile(timings_in_ms, 50),
        'p90', percentile(timings_in_ms, 90),
        'p99', percentile(timings_in_ms, 99),
        'p100_max', timings_in_ms[-1],
        'pstdev': statistics.pstdev(timings_in_ms),
        'sum': total

def percentile(sorted_data, percent):
    Find the percentile of a list of values.

    @parameter sorted_data - is an ALREADY SORTED list of values
    @parameter percent - a float value from 0.0 to 1.0.

    @return - the percentile of the values
    assert 0 <= percent < 1
    index = (len(sorted_data)-1) * percent
    return sorted_data[int(index)]