pywebworker 0.0.7a1

Python tools for interacting with Web Workers in Pyodide

PyWebWorker

Background

Out-of-the box Pyodide lacks support for a pure Python solution to using web workers. PyWebWorker seeks to fill that

gap by providing a set of Python objects and functions to interact with the Web Worker API.

Installation

PyWebWorker can be imported using micropip:

import micropip

await micropip.install('pywebworker')

Quick Reference

The examples here are valid as of Version 0.0.6

from pywebworker.worker import PyWorker



# This script will print a message to the console when the worker starts and

# will echo back any messages it receives

script = '''

console.log('worker created');

self.onmessage = function(message){

	console.log('Received: ' + message.data);

	self.postMessage(message.data);

}

'''



worker = PyWorker(script)

worker.start()



# the script echos back whatever we send, that message should be ready for us

worker.send_message('This is the first message')

messages = worker.get_unread_messages()



# messages have a .read method so the consumer knows what has and has not been processed

print([message.read() for message in messages])



# the message list can be checked for any unread messages using the has_unread_messages method

worker.send_message('This is the second message')

print(worker.has_unread_messages())



# individual messages can be checked to see if they have been read or not

first_message = worker.get_message(0)

second_message = worker.get_message(1)

print(first_message.is_opened())

print(second_message.is_opened())



# this isn't recommended, but if you really need to check for new messages without using has_unread_messages() or

# get_unread_messages(), _update_messages() will update the messages attribute.

# PLEASE NOTE THAT THIS IS A TEMPORARY WAY TO UPDATE THE LIST, THIS WILL BE REMOVED LATER

worker.send_message('This is the third message')

worker._update_messages()

print(worker.get_message(2).read())



# killing the worker stops it *immediately*. Anything in-progress will be stopped, so only use this when it is certain

# the worker is done and no longer needed!

worker.kill()

Roadmap

This timeline is tentative and subject to change

Version 0.1.0

• PyWorker and JsWorker as objects that run either Python or JavaScript, respectively

• Exception handling for common errors

• Message queues for inbound/outbound messages to the worker

• Enhancements to underlying JavaScript

• Add tests for basic object functions

Version 0.2.0

• Ability to execute scripts from Enscriptem and URI's

• Place JavaScript for underlying JS objects into its own file (as opposed to text in a python module)

Version 0.X.0: Planned near-future but not scheduled

• Ability to pass environment settings to the interpreter in PyWorkers (currently runs on defaults)

• Creation of flexible thread pool for PyWorkers

Known Limitations

PyWorkers are slow to start

In order to run Pyodide in a worker, it must be downloaded and started in each worker thread, which takes time. The

goal is to eventually have a pool of threads that start this process in the background on import.