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Body: [`StreamingResponse` docs](https://fastapi.tiangolo.com/advanced/custom-response/?h=responses#streamingresponse) state: > Takes an async generator or a normal generator/iterator However based on https://github.com/Kludex/starlette/discussions/1776#discussioncomment-3207518 `async` generetors need something `await`ed to work: ```py import asyncio from time import sleep from fastapi import FastAPI from fastapi.responses import StreamingResponse app = FastAPI() async def fake_video_streamer(): for i in range(10): sleep(0.1) yield b"some fake video bytes" # await asyncio.sleep(0) # <-- uncomment to fix example @app.get("/") async def main(): """ this is as per https://fastapi.tiangolo.com/advanced/custom-response/?h=responses#streamingresponse but does not to work (blocks for 1 sec, then returns all chunks at once): curl -sNo- localhost:8000 wget -qO- localhost:8000 """ return StreamingResponse(fake_video_streamer()) ``` - `uvicorn==0.40.0` - `fastapi==0.128.0` --- Comments --- User: casperdcl It seems based on https://github.com/Kludex/starlette/discussions/1776#discussioncomment-3207518 that `await asyncio.sleep(0)` needs to be added to the documented example to work. User: mirza-mohibul-hasan Hi @casperdcl, thanks for raising this. I understand the issue and the root cause with async generators blocking without an await. If the fix isn’t already finalized, I’d be happy to work on this or help refine the docs/validate the example. Please let me know if that works for you. User: casperdcl fixed in #14681pull/14859/head
Akash Wankhede
5 months ago