advanced patterns when using FastAPI's BackgroundTasks with async functions
I keep running into I'm dealing with I'm working on a personal project and I've searched everywhere and can't find a clear answer... I'm working with an scenario when trying to use FastAPI's `BackgroundTasks` with an asynchronous function. I have a simple FastAPI application where I want to send an email in the background after a user registers. However, the email sending logic doesn't seem to work as expected when wrapped in `BackgroundTasks`. Below is a simplified version of my code: ```python from fastapi import FastAPI, BackgroundTasks from fastapi.responses import JSONResponse import asyncio app = FastAPI() async def send_email(email: str): # Simulating a long-running task await asyncio.sleep(5) # Simulating network delay print(f"Email sent to {email}") @app.post("/register/") async def register_user(email: str, background_tasks: BackgroundTasks): background_tasks.add_task(send_email, email) return JSONResponse(content={"message": "User registered!"}, status_code=201) ``` When I hit the `/register/` endpoint, it returns immediately with a 201 status, which is expected. However, the email is never sent. I checked the logs and there are no errors being raised, but I don't see the `print` statement executing. I suspect that the asynchronous handling with `BackgroundTasks` might not be working as I intended. I've tried changing the `send_email` function to a regular function (without `async` and `await`), and in that case, the email sending works, but I really want to keep it asynchronous due to the potential load from multiple requests. Is there something I'm missing about how FastAPI handles async tasks with `BackgroundTasks`? I am using FastAPI version 0.68.0 and Python 3.9.7. This is part of a larger CLI tool I'm building. Thanks in advance! This issue appeared after updating to Python 3.11. I'd love to hear your thoughts on this. I appreciate any insights! Any suggestions would be helpful.