Lots of ResourceWarning in FastApi with asyncpg - python-asyncio

Question

I have an async FastApi application with async sqlalchemy, source code:
database.py
from sqlalchemy import (
Column,
String,
)
from sqlalchemy.ext.asyncio import AsyncSession, create_async_engine
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker
from sqlalchemy.orm.decl_api import DeclarativeMeta
from app.config import settings
engine = create_async_engine(settings.DATABASE_URL, pool_per_ping=True)
Base: DeclarativeMeta = declarative_base()
async_session = sessionmaker(engine, class_=AsyncSession, expire_on_commit=False)
class Titles(Base):
__tablename__ = "titles"
id = Column(String(100), primary_key=True)
title = Column(String(100), unique=True)
async def get_session() -> AsyncSession:
async with async_session() as session:
yield session
routers.py
import .database
from fastapi_utils.cbv import cbv
from fastapi_utils.inferring_router import InferringRouter
router = InferringRouter()
async def get_titles(session: AsyncSession):
results = await session.execute(select(database.Titles)))
return results.scalars().all()
#cbv(router)
class TitlesView:
session: AsyncSession = Depends(database.get_session)
#router.get("/titles", status_code=HTTP_200_OK)
async def get(self) -> List[TitlesSchema]:
results = await get_titles(self.session)
return [TitlesSchema.from_orm(result) for result in results]
main.py
from fastapi import FastAPI
from app.routers import router
def create_app() -> FastAPI:
fast_api_app = FastAPI()
fast_api_app.include_router(router, prefix="/", tags=["Titles"])
return fast_api_app
app = create_app()
manage.py
import asyncio
import sys
from .database import async_session, Base, engine
async def init_models():
async with engine.begin() as conn:
await conn.run_sync(Base.metadata.create_all, checkfirst=True)
if __name__ == "__main__":
asyncio.run(init_models())
sys.stdout.write("Models initiated\n")
It runs with docker:
python manage.py
CMD ["uvicorn", "main:app", "--reload", "--host", "0.0.0.0", "--port", "8000", "--limit-max-requests", "10000"]
And right after i see message Models initiated, after init_models() func i see couple of warnings:
app_1 | Models initiated
app_1 | /usr/local/lib/python3.9/site-packages/asyncpg/connection.py:131: ResourceWarning: unclosed connection <asyncpg.connection.Connection object at 0x7efe5a613c80>; run in asyncio debug mode to show the traceback of connection origin
app_1 | /usr/local/lib/python3.9/asyncio/sslproto.py:320: ResourceWarning: unclosed transport <asyncio.sslproto._SSLProtocolTransport object at 0x7efe5a631700>
app_1 | /usr/local/lib/python3.9/asyncio/selector_events.py:704: ResourceWarning: unclosed transport <_SelectorSocketTransport fd=6>
app_1 | INFO: Uvicorn running on http://0.0.0.0:5000 (Press CTRL+C to quit)
app_1 | INFO: Started reloader process [15] using statreload
app_1 | INFO: Started server process [17]
app_1 | INFO: Waiting for application startup.
app_1 | INFO: Application startup complete.
And after i make changes, i see a bunch of warnings:
app_1 | WARNING: StatReload detected file change in 'ref_info/main.py'. Reloading...
app_1 | INFO: Shutting down
app_1 | INFO: Waiting for application shutdown.
app_1 | INFO: Application shutdown complete.
app_1 | INFO: Finished server process [15]
app_1 | sys:1: ResourceWarning: unclosed file <_io.TextIOWrapper name=0 mode='r' encoding='UTF-8'>
app_1 | INFO: Started server process [16]
app_1 | INFO: Waiting for application startup.
app_1 | INFO: Application startup complete.
Is it ok, and i need to hide it? Or i setted up smth wrong?

Answer 1

Ok, i solved it.
engine = create_async_engine(
settings.DATABASE_ASYNC_URI,
echo="debug" if settings.DEBUG else False,
)
async_session = sessionmaker(
bind=engine,
class_=AsyncSession,
autoflush=True,
autocommit=False,
expire_on_commit=False,
)
async def get_session() -> AsyncGenerator[AsyncSession, None]:
async with async_session() as session:
assert isinstance(session, AsyncSession)
yield session
async def connect() -> None:
async with engine.begin() as conn:
await conn.run_sync(Base.metadata.create_all, checkfirst=True)
async def disconnect() -> None:
if engine:
await engine.dispose()
Add connect and disconnect to your FastApi app startapp and shutdown events