lesson05_semaphore.py

# SuperFastPython.com
# example of using an asyncio semaphore
from random import random
import asyncio

# task coroutine
async def task(semaphore, number):
 # acquire the semaphore
 async with semaphore:
 # generate a random value between 0 and 1
 value = random()
 # suspend for a moment
 await asyncio.sleep(value)
 # report a message
 print(f'Task {number} got {value}')

# main coroutine
async def main():
 # create the shared semaphore
 semaphore = asyncio.Semaphore(2)
 # create and schedule tasks
 tasks = [asyncio.create_task(task(semaphore, i))
 for i in range(10)]
 # wait for all tasks to complete
 _ = await asyncio.wait(tasks)

# start the asyncio program
asyncio.run(main())