GitHub Repository: sagemathinc/wapython
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CoWasm-Python: Collaborative Python in WebAssembly for Servers and Browsers

URL: https://github.com/sagemathinc/cowasm/python/README.md

DEMOS:

https://cowasm.org - Python using SharedArrayBuffers
https://zython.org - Python using Service Workers
https://cowasm.sh - Dash Shell with Python, Sqlite, Lua, etc., using SharedArrayBuffers

Type this if you have nodejs at least version 16 installed:

~$ npx python-wasm  # pnpm dlx python-wasm  or  yarn dlx python-wasm
Python 3.11.0 (main, Oct 27 2022, 10:03:11) [Clang 15.0.3 (git@github.com:ziglang/zig-bootstrap.git 0ce789d0f7a4d89fdc4d9571 on wasi
Type "help", "copyright", "credits" or "license" for more information.
>>> 2 + 3
5
>>> import numpy
>>> import sympy
>>> import pandas
...

What is this?

See https://github.com/sagemathinc/cowasm for more about the CoWasm project.

Try python-wasm

Try the python-wasm REPL under node.js (version at least 16):

~$ npx python-wasm
Python 3.11.0 (main, Oct 27 2022, 10:03:11) [Clang 15.0.3 (git@github.com:ziglang/zig-bootstrap.git 0ce789d0f7a4d89fdc4d9571 on wasi
Type "help", "copyright", "credits" or "license" for more information.
>>> 2 + 3
5
>>> import sys; sys.version
'3.11.0 (main, Oct 27 2022, 10:03:11) [Clang 15.0.3 ([email protected]:ziglang/zig-bootstrap.git 0ce789d0f7a4d89fdc4d9571'
>>> sys.platform
'wasi'

Install python-wasm

Install python-wasm into your project, and try it via the library interface and the node.js terminal.

pnpm install python-wasm

Then from the nodejs REPL:

~/cowasm/packages/python-wasm$ node
Welcome to Node.js v19.0.0.
Type ".help" for more information.
> {syncPython, asyncPython} = require('python-wasm')
{
  syncPython: [AsyncFunction: syncPython],
  asyncPython: [AsyncFunction: asyncPython],
  default: [AsyncFunction: asyncPython]
}
> python = await syncPython(); 0;
0
> python.exec('import sys')
undefined
> python.repr('sys.version')
"'3.11.0b3 (main, Jul 14 2022, 22:22:40) [Clang 13.0.1 ([email protected]:ziglang/zig-bootstrap.git 623481199fe17f4311cbdbbf'"
> python.exec('import numpy')
undefined
> python.repr('numpy.linspace(0, 10, num=5)')
'array([ 0. ,  2.5,  5. ,  7.5, 10. ])'

There is also a Python REPL that is part of python-wasm:

> python.terminal()
Python 3.11.0 (main, Oct 27 2022, 10:03:11) [Clang 15.0.3 (git@github.com:ziglang/zig-bootstrap.git 0ce789d0f7a4d89fdc4d9571 on wasi
Type "help", "copyright", "credits" or "license" for more information.
>>> 2 + 3   # you can edit using readline
5
>>> input('name? ')*3
name? william  <-- I just typed "william"
'williamwilliamwilliam'
>>> import time; time.sleep(3)  # sleep works
>>> while True: pass   # ctrl+c works, but exits this terminal
> # back in node.

You can also use python-wasm in your own web applications via webpack. In the browser, this transparently uses SharedArrayBuffers if available, and falls back to ServiceWorkers.

Build from Source

We support and regularly test building CoWasm-Python from source on the following platforms:

x86_64 macOS and aarch64 macOS (Apple Silicon M1)
x86_64 and aarch64 Linux

See the top level README.md file.

Benchmarks

There is a collection of cpu-intensive benchmarks in packages/bench/src, which you can run under various Python interpreters by running

your-python-interpreter src/all.py

Here are some grand total times that I recorded at some point in time in the past. Don't take them too seriously. That said, I chose the parameters of the benchmarks so a single benchmark doesn't unduly impact the results (e.g., it is easy to game any such benchmark by adjusting parameters).

Python	x86_64 Linux	MacOS M1 max	aarch64 Linux (docker on M1 max)
PyPy 3.9.x (Python reimplemented with a JIT)	2997 ms	2127 ms	1514 ms (ver 3.6.9)
pylang (Javascript Python -- see https://github.com/sagemathinc/pylang)	6909 ms	2876 ms	4424 ms
Native CPython 3.11	9284 ms	4491 ms	4607 ms
WebAssembly CPython (python-wasm)	23109 ms	12171 ms	12909 ms

The quick summary is that in each case pypy is twice as fast as pylang (basically node.js), python-lang is twice as fast as cpython, and native cpython is about 2.5x as fast as python-wasm. However, when you study the individual benchmarks, there are some significant differences. E.g., in brython.py there is a benchmark "create instance of simple class" and it typically takes 4x-5x longer in WebAssembly versus native CPython.

Contact

Email [email protected] or @wstein389 if find this interesting and want to help out.

CoWasm is an open source 3-clause BSD licensed project. It includes components and dependencies that may be licensed in other ways, but nothing is GPL licensed, except some code in the sagemath subdirectory (which nothing else depends on).