New version causes high CPU load with --reload

[plaa]

After upgrading uvicorn (0.14.0 -> 0.17.6) my local dev environment docker CPU usage went up from 5% to a continuous 65% when using --reload. While this doesn't impact production usage, it's quite a crappy development experience with fans howling constantly.

I'm running on macOS Monterey using Docker Desktop on a 2018 MBP, processor 2,6 GHz 6-Core Intel Core i7.

[Kludex]

What's the list of dependencies on that environment?

[plaa]

$ poetry show
aiofiles                 0.6.0
aiohttp                  3.8.1
aiojobs                  1.0.0
aiomcache                0.6.0
aioredis                 1.3.1
aiosignal                1.2.0
alembic                  1.7.6
anyio                    3.5.0
aresponses               2.1.5
asgiref                  3.5.0
astroid                  2.9.3
async-timeout            4.0.2
asyncpg                  0.25.0
attrs                    21.4.0
azure-common             1.1.28
azure-core               1.22.1
azure-servicebus         7.6.0
bcrypt                   3.2.0
black                    22.1.0
bleach                   4.1.0
broadcaster              0.2.0
cachecontrol             0.12.11
cached-property          1.5.2
cachy                    0.3.0
celery-types             0.3.1
certifi                  2021.10.8
cffi                     1.15.0
charset-normalizer       2.0.12
cleo                     0.8.1
click                    8.0.3
clikit                   0.6.2
coverage                 5.5
crashtest                0.3.1
dependency-injector      4.38.0
distlib                  0.3.4
dnspython                2.2.0
dparse                   0.5.1
email-validator          1.1.3
et-xmlfile               1.1.0
fastapi                  0.75.0
fastapi-plugins          0.9.0
fastapi-utils            0.2.1
fastapi-versioning       0.10.0
fastapi-websocket-pubsub 0.1.21
fastapi-websocket-rpc    0.1.21
filelock                 3.4.2
flake8                   4.0.1
freezegun                1.2.1
frozenlist               1.3.0
geoalchemy2              0.9.4
gino                     1.0.1
gunicorn                 20.1.0
h11                      0.12.0
hiredis                  2.0.0
html5lib                 1.1
httpcore                 0.14.7
httpx                    0.22.0
idna                     3.3
importlib-metadata       4.11.1
iniconfig                1.1.1
invoke                   1.6.0
isodate                  0.6.1
isort                    5.10.1
itsdangerous             1.1.0
keyring                  23.5.0
lazy-object-proxy        1.7.1
lockfile                 0.12.2
lxml                     4.7.1
mako                     1.1.6
markupsafe               2.0.1
mccabe                   0.6.1
msgpack                  1.0.3
msrest                   0.6.21
multidict                6.0.2
mypy                     0.940+dev.52dc066692e0ecc6f78dfe2ee3a9e316b749ab2d 52dc066
mypy-extensions          0.4.3
oauthlib                 3.2.0
openpyxl                 3.0.9
orjson                   3.6.7
owslib                   0.20.0
packaging                20.9
passlib                  1.7.4
pastel                   0.2.1
pathspec                 0.9.0
pexpect                  4.8.0
pint                     0.18
pkginfo                  1.8.2
platformdirs             2.5.0
pluggy                   1.0.0
poetry                   1.1.13
poetry-core              1.0.7
polib                    1.1.1
psycopg2-binary          2.9.3
ptyprocess               0.7.0
py                       1.11.0
pycodestyle              2.8.0
pycparser                2.21
pycryptodomex            3.14.1
pydantic                 1.9.0
pyflakes                 2.4.0
pyjwt                    2.3.0
pylev                    1.4.0
pylint                   2.12.2
pyparsing                3.0.7
pyproj                   3.3.0
pytest                   7.0.1
pytest-asyncio           0.18.1
python-dateutil          2.8.2
python-dotenv            0.19.2
python-json-logger       2.0.2
python-multipart         0.0.5
pytz                     2021.3
pyyaml                   5.4.1
redis                    3.5.3
requests                 2.27.1
requests-file            1.5.1
requests-oauthlib        1.3.1
requests-toolbelt        0.9.1
respx                    0.17.1
rfc3986                  1.5.0
rope                     0.16.0
safety                   1.10.3
sentry-sdk               1.5.5
shellingham              1.4.0
six                      1.16.0
sniffio                  1.2.0
sqlalchemy               1.3.24
sqlalchemy-stubs         0.3
sqlalchemy-utc           0.14.0
sqlalchemy-utils         0.37.9
sse-starlette            0.10.3
starlette                0.17.1
tenacity                 8.0.1
toml                     0.10.2
tomli                    2.0.1
tomlkit                  0.7.2
types-bleach             4.1.4
types-python-dateutil    2.8.9
types-pytz               2021.3.5
types-pyyaml             6.0.4
typing-extensions        4.1.1
uamqp                    1.5.1
unittest-xml-reporting   2.5.2
urllib3                  1.26.8
uvicorn                  0.17.6
virtualenv               20.13.1
webencodings             0.5.1
websockets               10.1
wrapt                    1.13.3
yarl                     1.7.2
zeep                     4.1.0
zipp                     3.7.0

[Kludex]

Can you try to install watchgod and see if it improves?

[plaa]

Thanks, installing watchgod fixed the issue. 👍

For anyone else wondering, before installing uvicorn printed out:
INFO: Started reloader process [7] using statreload

Afterwards uvicorn prints out:
INFO: Started reloader process [8] using watchgod

Documentation here: https://www.uvicorn.org/settings/#reloading-without-watchgod

[plaa]

I verified that the regression occurs between uvicorn versions 0.14.0 --> 0.15.0. The same occurs on a colleague's environment using Intel Mac, but does not occur on a Linux dev environment.

[ccrvlh]

I've been experiencing high CPU usage at startup (without reload), using version 0.17.6. This is not much of an issue while running, but it makes the pod very slow to startup (anywhere from 60-90 seconds) after the container has been created. Maybe this is related? Looking at the logs, there's nothing before startup, (I'll try to use debug to see if anything comes up) and after 1-2minutes the "Started server process" appears, and then the application startup is completed immediately.

Tried again with debug (--log-level debug), but no messages except from the info.

[euri10]

@lowercase00 it's probably not related at all.
if you want assistance on this show us a minimal example, in another discussion.
I think it may most likely be related to the lifespan startup where you may initialize stuff that takes a lot of resources, but without more specifics it's hard to know, in any case it's a different topic than this one.