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ViewsRunning separate infinite background thread in a python webapp (fastapi/flask/django)
How can i launch an application which does below 2 things:
- Expose rest endpoint via FastAPI.
- Run a seperate thread infintely (rabbitmq consumer - pika) waiting for request.
Below is the code through which i am launching the fastAPI server. But when i try to run a thread, before execution of below line, it says coroutine was never awaited.
How can both be run parallely?
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Santiago Trujillo
2 answers
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Maybe this is not the answer you are looking for. There is a library called celery that makes multithreading easy to manage in python.
Check it out: https://docs.celeryproject.org/en/stable/getting-started/introduction.html
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Santiago Trujillo
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import asyncio
from concurrent.futures import ThreadPoolExecutor
from fastapi import FastAPI
import uvicorn
app = FastAPI()
def run(corofn, *args):
loop = asyncio.new_event_loop()
try:
coro = corofn(*args)
asyncio.set_event_loop(loop)
return loop.run_until_complete(coro)
finally:
loop.close()
async def sleep_forever():
await asyncio.sleep(1000)
#
async def main():
loop = asyncio.get_event_loop()
executor = ThreadPoolExecutor(max_workers=2)
futures = [loop.run_in_executor(executor, run, sleep_forever),
loop.run_in_executor(executor, run, uvicorn.run, app)]
print(await asyncio.gather(*futures))
if __name__ == '__main__':
loop = asyncio.get_event_loop()
loop.run_until_complete(main())
Note: This may hinder your FastAPI performance. Better approach would be to use a Celery Task
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Santiago Trujillo
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