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Background Tasks stuck other requests when i use a http middleware

See original GitHub issue

First Check

I added a very descriptive title to this issue.
I used the GitHub search to find a similar issue and didn’t find it.
I searched the FastAPI documentation, with the integrated search.
I already searched in Google “How to X in FastAPI” and didn’t find any information.
I already read and followed all the tutorial in the docs and didn’t find an answer.
I already checked if it is not related to FastAPI but to Pydantic.
I already checked if it is not related to FastAPI but to Swagger UI.
I already checked if it is not related to FastAPI but to ReDoc.

Commit to Help

I commit to help with one of those options 👆

Example Code

import time

from fastapi import FastAPI, BackgroundTasks, Request, Response
from loguru import logger

app = FastAPI()


@app.middleware("http")
async def logger_request(request: Request, call_next) -> Response:
    logger.debug(f"http middleware [{request.url}]")
    response = await call_next(request)
    return response


class Worker:
    def __init__(self, arg):
        self.arg = arg
        logger.debug(f"worker[{arg}] init")

    def work(self):
        for i in range(10):
            logger.debug(f"worker[{self.arg}] work[{i}]")
            time.sleep(1)


@app.get("/")
async def root():
    return {"message": "Hello World"}


@app.get("/work/{worker_id}")
async def work(back_task: BackgroundTasks, worker_id: int):
    worker = Worker(worker_id)
    back_task.add_task(worker.work)

    return {"message": f"work[{worker_id}] created"}


@app.get("/hello/{name}")
async def say_hello(name: str):
    return {"message": f"Hello {name}"}

Description

router “/work/{worker_id}” would create a task(a sync task, actually) on backgroud, after calling it, other new requests will stuck until the task finish
it just happen when i use a http middleware
i knew it is a starlette issue but i could not find a solution yet, anybody tell me how to solve this?