Line Profiler¶

The line_profiler module for doing line-by-line profiling of functions

Github	https://github.com/pyutils/line_profiler
Pypi	https://pypi.org/project/line_profiler
ReadTheDocs	https://kernprof.readthedocs.io/en/latest/

Installation¶

Releases of line_profiler and kernprof can be installed using pip

pip install line_profiler

The package also provides extras for optional dependencies, which can be installed via:

pip install line_profiler[all]

Line Profiler Basic Usage¶

To demonstrate line profiling, we first need to generate a Python script to profile. Write the following code to a file called demo_primes.py.

from line_profiler import profile


@profile
def is_prime(n):
    '''
    Check if the number "n" is prime, with n > 1.

    Returns a boolean, True if n is prime.
    '''
    max_val = n ** 0.5
    stop = int(max_val + 1)
    for i in range(2, stop):
        if n % i == 0:
            return False
    return True


@profile
def find_primes(size):
    primes = []
    for n in range(size):
        flag = is_prime(n)
        if flag:
            primes.append(n)
    return primes


@profile
def main():
    print('start calculating')
    primes = find_primes(100000)
    print(f'done calculating. Found {len(primes)} primes.')


if __name__ == '__main__':
    main()

In this script we explicitly import the profile function from line_profiler, and then we decorate function of interest with @profile.

By default nothing is profiled when running the script.

python demo_primes.py

The output will be

start calculating
done calculating. Found 9594 primes.

The quickest way to enable profiling is to set the environment variable LINE_PROFILE=1 and running your script as normal.

LINE_PROFILE=1 python demo_primes.py

This will output 3 files: profile_output.txt, profile_output_<timestamp>.txt, and profile_output.lprof and stdout will look something like:

start calculating
done calculating. Found 9594 primes.
Timer unit: 1e-09 s

  0.65 seconds - demo_primes.py:4 - is_prime
  1.47 seconds - demo_primes.py:19 - find_primes
  1.51 seconds - demo_primes.py:29 - main
Wrote profile results to profile_output.txt
Wrote profile results to profile_output_2023-08-12T193302.txt
Wrote profile results to profile_output.lprof
To view details run:
python -m line_profiler -rtmz profile_output.lprof

For more control over the outputs, run your script using kernprof. The following invocation will run your script, dump results to demo_primes.py.lprof, and display results.

python -m kernprof -lvr demo_primes.py

Note: the -r flag will use “rich-output” if you have the rich module installed.

Line Profiler¶

Installation¶

Line Profiler Basic Usage¶

Indices and tables¶