Throttling Async Functions in Python Asyncio

Question

I have a list of awaitables that I want to pass to the asyncio.AbstractEventLoop but I need to throttle the requests to a third party API.

Answer 1

Another solution - using bounded semaphores - by a coworker, mentor, and friend, is the following:

import asyncio


class AsyncLeakyBucket(object):

    def __init__(self, max_tasks: float, time_period: float = 60, loop: asyncio.events=None):
        self._delay_time = time_period / max_tasks
        self._sem = asyncio.BoundedSemaphore(max_tasks)
        self._loop = loop or asyncio.get_event_loop()
        self._loop.create_task(self._leak_sem())

    async def _leak_sem(self):
        """
        Background task that leaks semaphore releases based on the desired rate of tasks per time_period
        """
        while True:
            await asyncio.sleep(self._delay_time)
            try:
                self._sem.release()
            except ValueError:
                pass

    async def __aenter__(self) -> None:
        await self._sem.acquire()

    async def __aexit__(self, exc_type, exc, tb) -> None:
        pass

Can still be used with the same async with bucket code as in @Martijn's answer