# Online Python - IDE, Editor, Compiler, Interpreter
 
import asyncio
import sys
import typing
from collections.abc import Awaitable, Iterable
 
 
ConsumerId = int
 
tasks: dict[ConsumerId, Awaitable] = {}
sem = asyncio.Semaphore(4)
 
async def consumer(data, consumer_id: ConsumerId):
    try:
        print(f'Starting consumer {consumer_id}')
        print(f'Working on "{data}" ...')
        await asyncio.sleep(2)
        print(f'Exiting consumer {consumer_id}')
    finally:
        sem.release()
        # If we exited cleanly, just remove ourselves from `tasks` dict because nobody needs to await us.
        if not sys.exc_info()[0]:
            del tasks[consumer_id]
 
async def main(producer: Iterable):
    for consumer_id, data in enumerate(producer):
        await sem.acquire()
        consumer_task = asyncio.create_task(consumer(data, consumer_id = consumer_id))
        tasks[consumer_id] = consumer_task
 
    # At this point just await all the remaining tasks which are either still running or had exited with exception
    for coro in asyncio.as_completed(tasks.values()):
        try:
            await coro
        except Exception as exc:
            print(f'Do something about {exc}')
 
producer = range(100)
asyncio.run(main(producer = producer))

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