implementing Concurrent Database Access in FastAPI with SQLAlchemy and AsyncSession
I'm trying to figure out I've been banging my head against this for hours... I'm relatively new to this, so bear with me. I'm working with a question with concurrent database access in my FastAPI application when using SQLAlchemy's AsyncSession. I have a simple endpoint that fetches user data based on an ID. However, when multiple requests come in simultaneously, I receive the following behavior intermittently: `sqlalchemy.exc.InvalidRequestError: This session is not bound to a connection`. Here's a simplified version of my code: ```python from fastapi import FastAPI, Depends, HTTPException from sqlalchemy.ext.asyncio import AsyncSession, create_async_engine, async_sessionmaker from sqlalchemy.orm import sessionmaker from sqlalchemy.ext.declarative import declarative_base DATABASE_URL = "postgresql+asyncpg://user:password@localhost/dbname" engine = create_async_engine(DATABASE_URL, echo=True) Base = declarative_base() SessionLocal = async_sessionmaker(bind=engine, class_=AsyncSession) app = FastAPI() class User(Base): __tablename__ = "users" id = Column(Integer, primary_key=True, index=True) name = Column(String) async def get_db() -> AsyncSession: async with SessionLocal() as session: yield session @app.get("/users/{user_id}") async def read_user(user_id: int, db: AsyncSession = Depends(get_db)): user = await db.get(User, user_id) if user is None: raise HTTPException(status_code=404, detail="User not found") return user ``` I've tried wrapping the database call in a try-except block to handle the behavior, but it doesn't resolve the underlying scenario. The application works fine when I send requests sequentially, but the question arises under concurrent load. Additionally, I noticed that if I set the `pool_pre_ping` parameter to True in the `create_async_engine`, it sometimes helps, but not consistently. Do I need to change how I'm managing the sessions or is there a different approach to handle concurrent requests better with SQLAlchemy's AsyncSession? My development environment is Ubuntu. I'm working on a web app that needs to handle this. This is part of a larger API I'm building. Has anyone else encountered this? Is there a simpler solution I'm overlooking? This is part of a larger REST API I'm building. Thanks, I really appreciate it! My team is using Python for this mobile app. I'd really appreciate any guidance on this. What's the best practice here?