advanced patterns with FastAPI and Background Tasks Not Executing as Expected
I've been struggling with this for a few days now and could really use some help. I'm running a FastAPI application (version 0.68.0) where I attempt to use background tasks to send emails after a user registers. However, the background task doesn't seem to trigger, and I'm not receiving any errors in the logs. I've set up my endpoint like this: ```python from fastapi import FastAPI, BackgroundTasks from fastapi.responses import JSONResponse app = FastAPI() @app.post('/register/') async def register_user(email: str, background_tasks: BackgroundTasks): # Simulate saving the user to a database await save_user_to_db(email) background_tasks.add_task(send_email, email) return JSONResponse(content={'message': 'User registered successfully.'}, status_code=201) async def send_email(email: str): # Simulate sending email print(f'Sending email to {email}') await asyncio.sleep(5) # Simulating delay print(f'Email sent to {email}') async def save_user_to_db(email: str): await asyncio.sleep(1) # Simulating DB save ``` I expected the `send_email` function to execute in the background after the user registration is complete, but it seems to be doing nothing. I've confirmed that the `save_user_to_db` function is working correctly, but the email never gets sent. I also checked my FastAPI configuration and ensured that the server runs with `uvicorn` (version 0.15.0). I've tried running the server with different workers but still face the same scenario. The event loop seems to be running since I can perform other async tasks without problems. I need to find anything in the documentation about the limitations of background tasks with FastAPI that could cause this. Any advice on what might be going wrong or how to debug this further would be greatly appreciated. For context: I'm using Python on Linux. I'd really appreciate any guidance on this. I'm using Python 3.10 in this project. Has anyone else encountered this?