Potential starvation with connection pool

I have the following piece of code where I initialize 100 workers and a connection pool of size 10. Each worker loops and trys to acquire a connection and hold it for 200ms.

import asyncio

import asyncpg


async def worker(pool: asyncpg.Pool):
    while True:
        async with pool.acquire(timeout=10):
            # hold the connection for 200ms
            await asyncio.sleep(0.2)


async def main():
    async with asyncpg.pool.create_pool(max_size=10) as pool:
        async with asyncio.TaskGroup() as tg:
            for _ in range(100):
                tg.create_task(worker(pool))


asyncio.run(main())

When running on my laptop, this code reliably crashes with a TimeoutError after a few minutes, meaning that at least one worker failed to acquire a connection after 10 seconds. Given that there're 10 workers per connection and each worker holds the connection for 200ms, I would expect workers to be able to acquire a connection every 2 seconds.

This looks like starvation to me. Are there fairness guarantees regarding connection pools? Is there anything I could do other than just increasing the max pool size?

首先，使用 asyncio.TaskGroup、100 个 workers 和 asyncpg.pool.create_pool(max_size=10) 运行提供的 Python 复现程序。检查 pool.acquire(timeout=10) 在竞争下的行为，并确定观察到的 TimeoutError 是反映了饥饿，还是预期的调度；完成标准是记录 fairness guarantee，或识别出一个可复现的 pool 缺陷。