Running uvicorn with watchfiles caused CPU usage >= 99% in docker container

Description

We have a fairly simple ASGI app served using uvicorn. To facilitate debug, we mount git repository in the host to docker. However, when running uvicorn with command

uvicorn main:app --port 8100 --host 0.0.0.0 --reload

will cause cpu to run at 100%, even if the app crashed with ImportError or other error. In such case, Ctrl+C will not be able to terminate uvicorn.

I tried to use command such as

watchfiles "sleep 100" provider_api

With or without WATCHFILES_FORCE_POLLING=1, no such error occurred.

docker file python:3.8 watchfiles version 0.16.1 uvicorn version 0.18.2

The host runs on Oracle ampere arm64 instance. It might having similar issue with M1 Mac?

Example Code

root@4af5866a294c:/# uvicorn main:app --port 8100 --host 0.0.0.0 --reload
INFO:     Will watch for changes in these directories: ['/']
INFO:     Uvicorn running on http://0.0.0.0:8100 (Press CTRL+C to quit)
INFO:     Started reloader process [170] using WatchFiles
Process SpawnProcess-1:
Traceback (most recent call last):
  File "/usr/local/lib/python3.8/multiprocessing/process.py", line 315, in _bootstrap
    self.run()
  File "/usr/local/lib/python3.8/multiprocessing/process.py", line 108, in run
    self._target(*self._args, **self._kwargs)
  File "/usr/local/lib/python3.8/site-packages/uvicorn/_subprocess.py", line 76, in subprocess_started
    target(sockets=sockets)
  File "/usr/local/lib/python3.8/site-packages/uvicorn/server.py", line 60, in run
    return asyncio.run(self.serve(sockets=sockets))
  File "/usr/local/lib/python3.8/asyncio/runners.py", line 44, in run
    return loop.run_until_complete(main)
  File "/usr/local/lib/python3.8/asyncio/base_events.py", line 616, in run_until_complete
    return future.result()
  File "/usr/local/lib/python3.8/site-packages/uvicorn/server.py", line 67, in serve
    config.load()
  File "/usr/local/lib/python3.8/site-packages/uvicorn/config.py", line 479, in load
    self.loaded_app = import_from_string(self.app)
  File "/usr/local/lib/python3.8/site-packages/uvicorn/importer.py", line 24, in import_from_string
    raise exc from None
  File "/usr/local/lib/python3.8/site-packages/uvicorn/importer.py", line 21, in import_from_string
    module = importlib.import_module(module_str)
  File "/usr/local/lib/python3.8/importlib/__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1014, in _gcd_import
  File "<frozen importlib._bootstrap>", line 991, in _find_and_load
  File "<frozen importlib._bootstrap>", line 975, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 671, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 843, in exec_module
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "/provider_api/main.py", line 25, in <module>
    from .models.slot_profile import SlotBulkUpdateRequest
ImportError: attempted relative import with no known parent package

Watchfiles Output

$ watchfiles 'echo reloaded' . --verbose
[02:26:04] watchfiles v0.16.1 👀  path="/" target="echo reloaded" (command) filter=DefaultFilter...
[02:26:04] running "echo reloaded" as command
reloaded
watcher: INotifyWatcher { channel: Sender { .. }, waker: Waker { inner: Waker { fd: File { fd: 5, path: "anon_inode:[eventfd]", read: true, write: true } } } }
[02:26:10] rust notify timeout, continuing
[02:26:15] rust notify timeout, continuing
raw-event: Event { kind: Modify(Metadata(Any)), paths: ["/run.py"], attr:tracker: None, attr:flag: None, attr:info: None, attr:source: None }
raw-event: Event { kind: Access(Close(Write)), paths: ["/run.py"], attr:tracker: None, attr:flag: None, attr:info: None, attr:source: None }
[02:26:17] 1 change detected: {(<Change.modified: 2>, '/run.py')}
[02:26:17] process already dead, exit code: 0
reloaded
[02:26:22] rust notify timeout, continuing

Operating System & Architecture

Linux-5.15.0-1016-oracle-aarch64-with-glibc2.35 #20-Ubuntu SMP Mon Aug 8 07:08:08 UTC 2022

Environment

Docker

Python & Watchfiles Version

python: 3.9.7 | packaged by conda-forge | (default, Sep 2 2021, 18:58:59) [GCC 9.4.0], watchfiles: 0.16.1

Rust & Cargo Version

No response