Pool created with min_size loses inactive connections and never re-acquires them

[bdoms]

I love asyncpg, been using it for years. However recently came across some unexpected behavior with v 0.30.0. It goes a little something like this.

Initialize a pool with a min_size:

import asyncio
import asyncpg

pool = await asyncpg.create_pool(min_size=10, max_size=20, **kwargs) # assume kwargs has connection info
print(f'Total: {pool.get_size()}')
# Total: 10

All good. But now let's say that nothing happens for over 5 minutes. You know, because max_inactive_connection_lifetime=300.0 by default. And check again:

await asyncio.sleep(305)
print(f'Total: {pool.get_size()}')
# Total: 0

Huh? Why isn't it still 10? No matter what I set for max_inactive_connection_lifetime this behavior happens immediately after that time, as long as the time is non-zero. If it's set to 0 then the behavior correctly doesn't happen.

I don't know if this is intentional or not, but as a developer, when I open a database pool with a minimum number of connections I expect that the pool will maintain that minimum, even if they are automatically closed or timeout.