A short script to demostrate how to use semaphore to manipulate async coroutines

semademo.py

#!/usr/bin/env python3
# -*- vim: set fileencoding=utf-8 ff=unix: -*-
from random import randint
import argparse, asyncio


async def wait4me(semaphore, taskno):
	async with semaphore:
		waittime = randint(1, 10)
		await asyncio.sleep(waittime)
		print(f'Task #{taskno} has waited {waittime} seconds.')
		return waittime


async def process(n, concurrency):
	semaphore = asyncio.Semaphore(concurrency)
	tasks = [asyncio.create_task(wait4me(semaphore, i)) for i in range(n)]
	results = await asyncio.gather(*tasks)
	print(results)


def getargs():
	parser = argparse.ArgumentParser(description='Async Semaphore Demo')
	parser.add_argument(
		'--concurrency',
		type=int,
		default=4,
		help='max number of simultaneous running tasks'
	)
	parser.add_argument(
		'--tasks',
		type=int,
		default=8,
		help='total number of tasks'
	)
	return parser.parse_args()


if '__main__' == __name__:
	args = getargs()
	asyncio.run(process(args.tasks, args.concurrency))