FastAPI: How to Handle Multiple Background Tasks with Dependencies without Blocking Requests?
After trying multiple solutions online, I still can't figure this out. I'm working on a FastAPI application where I need to perform multiple background tasks after a request is processed. However, I'm encountering issues with how to manage dependencies properly without blocking the main request. I've defined a background task that sends an email after a user registers, but I need to add another task that logs the registration to a database. Both tasks need to run asynchronously, but right now, the second task is blocking because it relies on the first one completing. Here's a simplified version of my code: ```python from fastapi import FastAPI, BackgroundTasks, Depends from sqlalchemy.orm import Session from . import models, schemas, database app = FastAPI() def log_registration(user: schemas.UserCreate, db: Session = Depends(database.get_db)): # Simulate a database logging operation new_log = models.Log(entry=f'User {user.email} registered') db.add(new_log) db.commit() async def send_email(email: str): pass # Simulate sending an email @app.post('/register/') async def register_user(user: schemas.UserCreate, background_tasks: BackgroundTasks, db: Session = Depends(database.get_db)): background_tasks.add_task(send_email, user.email) background_tasks.add_task(log_registration, user, db) return {'message': 'User registered successfully'} ``` When I run this code, it seems the logging function waits for the email task to finish before starting, which is not what I want. I expect both functions to run concurrently after the request is processed. I've tried using `asyncio.create_task()` to manage the tasks directly, but I'm not sure how to pass the dependencies correctly. What’s the best way to implement this without blocking requests and still using FastAPI’s dependency injection? Any suggestions on how I can achieve true concurrency in this scenario would be greatly appreciated! For context: I'm using Python on Windows 11.