Profile code executed by pytest
line-by-line profiling for code executed by pytest, using line-profiler.
Line profiler is a wonderful tool to easily identify bottlenecks inside specific functions of your code, and quantity the improvements after a refactor.
Using it is straightforward but required to instrument the functions you want to profile with a "virtual decorator"
and then execute "a trigger script" (some code that call the decorated functions somehow) via
kernprof.py which works as a python wrapper that undertand that decorator and register the functions to be profiled.
Altought it does its job, is a bit invasive: you need to have an special "instrumented" version of your code, and execute it in a way that potentially clashes with the way you do normally (for instance, through a shortcut command from your editor, another script, etc.)
Moreover, frequently in real case scenarios, "a trigger script" isn't just a simple function call. You need to prepare input data, connect to external resources, etc. And that's exactly what a test can do, right?
You can install "pytest-line-profiler" via pip from PyPI:
$ pip install pytest-line-profiler
Mark your test passing the functions you wants to profile as positional arguments,
@pytest.mark.line_profile.with_args(function1, function2, [...])
If your test exercises any of those functions, you'll get the profile result as a report.
For example, consider this example
import pytest def f(i): return i * 10 def g(n=10): return sum(f(i) for i in range(10)) @pytest.mark.line_profile.with_args(f, g) def test_as_mark(): assert g() == 450
After that test is executed, you'll get the stats from the line profiler instance.
============ Line Profile result for tests/test_line_profiler.py::test_as_mark ============ Timer unit: 1e-06 s Total time: 4e-06 s File: /home/tin/lab/pytest-line-profiler/tests/test_line_profiler.py Function: f at line 4 Line # Hits Time Per Hit % Time Line Contents ============================================================== 4 def f(i): 5 10 4.0 0.4 100.0 return i * 10 Total time: 3e-05 s File: /home/tin/lab/pytest-line-profiler/tests/test_line_profiler.py Function: g at line 7 Line # Hits Time Per Hit % Time Line Contents ============================================================== 7 def g(n=10): 8 1 30.0 30.0 100.0 return sum(f(i) for i in range(10))
Alternatively, you can run any test passing the function/s to profile from the command line
$ pytest --line-profile path.to.function_to_be profiled [...]
Contributions are very welcome. Tests can be run with pytest, please ensure the coverage at least stays the same before you submit a pull request.
Distributed under the terms of the MIT license, "pytest-line-profiler" is free and open source software
If you encounter any problems, please file an issue along with a detailed description.
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