Aborted connection to db: '...' user: '...' host: '...' (Got an error reading communication packets)

[jowin202]

Hello,
I try to connect my fastapi to mysql database with aiomysql.

The minimal code looks like

import aiomysql
import asyncio

async def connect_to_db():
    return await aiomysql.connect(host="localhost",port=3306,user="fastapi_user",password="fastapi_password", db="fastapi_db")

async def execute_query_and_fetch(query, params=None):
    conn = await connect_to_db()
    async with conn.cursor(aiomysql.DictCursor) as cursor:
        await cursor.execute(query, params)
        result = await cursor.fetchall()
        await cursor.close()
    conn.close()
    return result


print(asyncio.run(execute_query_and_fetch("SELECT * from users")))

This code is basically the same as this one here: https://aiomysql.readthedocs.io/en/stable/connection.html
whenever I call execute_query_and_fetch("SELECT ..."), I receive following error

mysql-1 | 2024-08-18 12:39:22 9 [Warning] Aborted connection 9 to db: 'fastapi_db' user: 'fastapi_user' host: '172.19.0.4' (Got an error reading communication packets)

However, I get the correct result, but anyway. There shouldn't be an error message for each query.

Has anyone an idea what happened here?

UPDATE: it works if I switch mariadb docker container to mysql, but anyway, is there a simple explanation?

[Cycloctane]

aiomysql simply closes the tcp connection without sending COM_QUIT packet when conn.close() is called.
You can use await conn.ensure_closed() to avoid error messages. ensure_closed() can send COM_QUIT and then close the connection safely.