async_lru_concurrent_writes.py

import asyncio
from collections import defaultdict
from async_lru import alru_cache

num_email_confirmations = defaultdict(int)


@alru_cache(maxsize=500)
async def send_email_confirmation(user_email: str) -> int:
    num_email_confirmations[user_email] += 1
    await asyncio.sleep(1)
    return num_email_confirmations[user_email]


async def send_confirmations() -> int:
    send_once = asyncio.create_task(send_email_confirmation("albert.einstein@example.com"))
    send_again = asyncio.create_task(send_email_confirmation("albert.einstein@example.com"))
    await send_once
    return await send_again


def main():
    result = asyncio.run(send_confirmations())
    assert result == 1


if __name__ == "__main__":
    main()