Packet sequence number wrong

[MarkReedZ]

Running wrk against a web page with a simple select caused my logs to fill up with errors. Aiomysql has no problem with the same exact code. I'll create a simple test later to reproduce this.

Unhandled exception:
<class 'asyncmy.errors.InternalError'>
InternalError('Packet sequence number wrong - got 102 expected 1')
Unhandled exception:
<class 'asyncmy.errors.InternalError'>
InternalError('Packet sequence number wrong - got 112 expected 1')

Using create_pool

await aiomysql.create_pool( autocommit=True, minsize=4, maxsize=20)

The page handler is just a simple select

  async with app.mysql_pool.acquire() as conn:
    async with conn.cursor() as cur:
        await cur.execute("SELECT * from table where ... ");

The wrk cmd

  wrk -t2 -c8 -d2s http://localhost/select

[trim21]

could you provide a full reproduction example？

[ipfans]

@trim21 it's a concurrcy bug that not easy to repoduce all the time. It could be happen when your program in high loads.

[trim21]

@trim21 it's a concurrcy bug that not easy to repoduce all the time. It could be happen when your program in high loads.

I understand, can you provide a minimal example?

[ipfans]

@trim21 I think the first example could reproduce this issue. But you may need try it multiple times

[trim21]

@trim21 I think the first example could reproduce this issue. But you may need try it multiple times

sadly I can't.

import asyncmy # 0.2.9
import fastapi

app = fastapi.FastAPI()


@app.on_event("startup")
async def startup_event():
    app.mysql_pool = await asyncmy.create_pool(
        autocommit=True,
        minsize=4,
        maxsize=20,
        ...
    )


@app.get("/test")
async def test():
    async with app.mysql_pool.acquire() as conn:
        async with conn.cursor() as cur:
            await cur.execute("...")

with uvicorn a:app --no-access-log and hey -z 3m -c 16 http://127.0.0.1:8000/test on win10/ubuntu

[romkazor]

Confirm. 0.2.7 same problem. 0.2.5 stable

[wonrax]

In my case using SQLAlchemy and FastAPI it always throws this error for this specific handler when querying for a large amount of rows. This still works locally for small dataset (dev database). Code obfuscated for legal reasons:

async def public_sitemap():
    async with get_async_session() as session:
        query = (
            select(
                SAC.name, # type: ignore
                SAC.s.label('cs'), # type: ignore
                SAC.ca.label('cca'), # type: ignore
                SAC.ua.label('cua'), # type: ignore
                SA.s.label('as'), # type: ignore
                SAR.y,
                SA.ca,
                SA.ua
            )
            .select_from(SAC)
            .join(SACM)
            .join(SA)
            .join(SAR)
            .where(filter_cond())
        )

        categories = {}
        for row in (await session.execute(query)).fetchall():
            if row.cs not in categories:
                categories[row.cs] = {
                    "n": row.n,
                    ...
                    "as": []
                }
            categories[row.cs]["as"].append({
                "t": row.t,
                ...
            })

        return {
            "categories": list(categories.values())
        }

While other handlers with similar or even heavier SQLAlchemy usage perform without any issue. I switched to aiomysql and it doesn't seem to error out anymore.

[trim21]

is it caused by zero dates? #101