Snake Oil

A picture of the Chinese water snake curtesy of the Hong Kong Biodiversity Information Hub (part of the Agriculture, Fisheries and Conservation Department)

`whoami`

Sindre Nistad

pronounced similar to cinder 🔥

Consultant @ Bouvet 🐧

						
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Showtime!

Profiling

deterministic vs. sampling profilers NOTE
Execute source .venv.linux/bin/activate


							uv run --active py-spy top --native --subprocesses -- python -m
							mandelbrot

on Linux

`numpy.ufunc`

Universal functions; used to define functions that should be evaluated elementwise on one (ore more) numpy array.
@np.vectorizecan take any function; including a function from an extension.


							from mandelbrot.implementations.cython.cython_naive import _compute

							# Replace exising (naïve) implementation with
							mandelbrot = np.vectorize(_compute.mandelbrot)

`cython`


					# cython: profile=True
					# cython: linetrace=True
					# distutils: define_macros=CYTHON_TRACE_NOGIL=1

NOTE: Can be veryslow

In cython_direct/_compute.pyx


							channel: int
							for channel in range(3):
								pixels[i, j, channel] = colormap[color_index][channel]


							for index in prange(width * height):
								i = index % width
								j = index // width

Inlining the function (@cython.inline) can also be done. This has been suggested by multiple speakers here already.
The remaining implementations will allbe parallelized.

Rust

via maturin &$PyO_3$

Parallelize the Rust code:


							cd src/mandelbrot/implementations/rust/rust_native
							cargo add ndarray --features rayon

then add


							use ndarray::{Array3, Array2, Zip};
							use ndarray::parallel::prelude::*;

and replace the for loop with


							Zip::indexed(pixels.view_mut()).par_for_each(|(i, j), val| {
								*val = mandelbrot(
									x.0 + (i as f64) * x_scale,
									y.0 + (j as f64) * y_scale,
									cutoff,
								)
							});

`numba`

Nvidia CUDA

via cuda-core

There is also PyOpenCL

Other tools

I tried using free-threaded Python in this example, but I was unable to get pygameto compile with it.
I tried adding an example of using LPython, but I was unable to get it to compile and function on Windows in time.
I was able to install GraalPy with necessary dependencies (on Linux). pygamedid compile (mostly). Fonts did not work. When running graal gave an error message saying "Systemic Graal compilation failure detected". Each frame (with the pure Python implementation) took ~30 seconds (compared to ~1s normally) numpy.f2pyallows you to use Fortran in Python codonis an alternative Python implementation

Source code & presentation

QR code to the repository for the source code and presentation. Points to https://github.com/sindre-nistad/snake-oil

Addendum

Sources

A History Of 'Snake Oil Salesmen'
by Lakshmi Gandhi (NPR)
Snake Oil Salesmen Were on to Something
by Cynthia Graber ( Scientific American)
Chinese Water Snake by Agriculture, Fisheries and Conservation Department, Hong Kong

Mandelbrot

A (complex) number $c$ is in the Mandelbrot set if

$ |z_{n}| \le 2 $

for all $ n \ge 0 $ \[\begin{aligned} z_{0} = 0 \\ z_{n+1} = z_{n}^2 + c \end{aligned}\]

Snake Oil

`whoami`

Profiling

`numpy.ufunc`

`cython`

Rust

Rust

`numba`

Nvidia CUDA

Nvidia CUDA

Other tools

Source code & presentation

Addendum

Sources

Further reading

Mandelbrot

Mandelbrot

Video explainers