Run uvicorn in Nomad

[nikita-b]

Hi everyone, I have a strange issue with uvicorn.

I'm trying to run uvicorn in nomad but I have the following error on each request:

ERROR:    Exception in ASGI application
Traceback (most recent call last):
  File "/usr/local/lib/python3.10/dist-packages/uvicorn/protocols/http/httptools_impl.py", line 404, in run_asgi
    result = await app(  # type: ignore[func-returns-value]
  File "/usr/local/lib/python3.10/dist-packages/uvicorn/middleware/proxy_headers.py", line 78, in __call__
    return await self.app(scope, receive, send)
  File "/usr/local/lib/python3.10/dist-packages/fastapi/applications.py", line 270, in __call__
    await super().__call__(scope, receive, send)
  File "/usr/local/lib/python3.10/dist-packages/starlette/applications.py", line 124, in __call__
    await self.middleware_stack(scope, receive, send)
  File "/usr/local/lib/python3.10/dist-packages/starlette/middleware/errors.py", line 184, in __call__
    raise exc
  File "/usr/local/lib/python3.10/dist-packages/starlette/middleware/errors.py", line 162, in __call__
    await self.app(scope, receive, _send)
  File "/usr/local/lib/python3.10/dist-packages/starlette/middleware/exceptions.py", line 75, in __call__
    raise exc
  File "/usr/local/lib/python3.10/dist-packages/starlette/middleware/exceptions.py", line 64, in __call__
    await self.app(scope, receive, sender)
  File "/usr/local/lib/python3.10/dist-packages/fastapi/middleware/asyncexitstack.py", line 21, in __call__
    raise e
  File "/usr/local/lib/python3.10/dist-packages/fastapi/middleware/asyncexitstack.py", line 18, in __call__
    await self.app(scope, receive, send)
  File "/usr/local/lib/python3.10/dist-packages/starlette/routing.py", line 680, in __call__
    await route.handle(scope, receive, send)
  File "/usr/local/lib/python3.10/dist-packages/starlette/routing.py", line 275, in handle
    await self.app(scope, receive, send)
  File "/usr/local/lib/python3.10/dist-packages/starlette/routing.py", line 65, in app
    response = await func(request)
  File "/usr/local/lib/python3.10/dist-packages/fastapi/routing.py", line 231, in app
    raw_response = await run_endpoint_function(
  File "/usr/local/lib/python3.10/dist-packages/fastapi/routing.py", line 162, in run_endpoint_function
    return await run_in_threadpool(dependant.call, **values)
  File "/usr/local/lib/python3.10/dist-packages/starlette/concurrency.py", line 41, in run_in_threadpool
    return await anyio.to_thread.run_sync(func, *args)
  File "/usr/local/lib/python3.10/dist-packages/anyio/to_thread.py", line 31, in run_sync
    return await get_asynclib().run_sync_in_worker_thread(
  File "/usr/local/lib/python3.10/dist-packages/anyio/_backends/_asyncio.py", line 918, in run_sync_in_worker_thread
    worker.start()
  File "/usr/lib/python3.10/threading.py", line 935, in start
    _start_new_thread(self._bootstrap, ())
RuntimeError: can't start new thread

Here Dockerfiles CMD:

CMD ["bash", "-c", "uvicorn --workers 1 --host 0.0.0.0 --port $PORT main:app"]

requirements.txt:

fastapi==0.85.0
uvicorn[standard]==0.18.3

How I can debug this issue? I don't have this issue with flask + Gunicorn and I think it's related to multithreading. Or maybe old kernel I use centos 7:

uname -r
3.10.0-1062.18.1.el7.x86_64

[euri10]

you seem to have a sync endpoint, care to paste your app ? --workers 1 is useless since it defaults to one anyways.
the issue is not in uvicorn imho