cProfile

November 8, 2022

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The cProfile module provides an interface to profile Python programs. A single function or an entire script or module can be profiled. As an example, the script shown below contains two functions that suspend execution for 2 and 4.5 seconds.

# ztest.py

import time


def slow():
    time.sleep(2)


def slower():
    time.sleep(4.5)


slow()

slower()

Use the terminal command given below to profile the script. This will output the profile results to the terminal as total time tottime and cumulative time cumtime.

$ python -m cProfile ztest.py

7 function calls in 6.503 seconds

   Ordered by: standard name

   ncalls  tottime  percall  cumtime  percall filename:lineno(function)
        1    0.000    0.000    6.503    6.503 ztest.py:1(<module>)
        1    0.000    0.000    2.002    2.002 ztest.py:4(slow)
        1    0.000    0.000    4.501    4.501 ztest.py:8(slower)
        1    0.000    0.000    6.503    6.503 {built-in method builtins.exec}
        2    6.502    3.251    6.502    3.251 {built-in method time.sleep}
        1    0.000    0.000    0.000    0.000 {method 'disable' of '_lsprof.Profiler' objects}

The output can be sorted using the sort arguments: calls, cumtime, cumulative, filename, line, module, name, ncalls, nfl, pcalls, stdname, time, and tottime. The example below sorts the output based on the total time.

$ python -m cProfile -s tottime ztest.py

7 function calls in 6.506 seconds

   Ordered by: internal time

   ncalls  tottime  percall  cumtime  percall filename:lineno(function)
        2    6.506    3.253    6.506    3.253 {built-in method time.sleep}
        1    0.000    0.000    4.501    4.501 ztest.py:8(slower)
        1    0.000    0.000    6.506    6.506 ztest.py:1(<module>)
        1    0.000    0.000    2.005    2.005 ztest.py:4(slow)
        1    0.000    0.000    6.506    6.506 {built-in method builtins.exec}
        1    0.000    0.000    0.000    0.000 {method 'disable' of '_lsprof.Profiler' objects}

See the Python documentation for more information about the profiler.