Litestar consumes high amount of CPU

[bpereto]

Description

Running litestar litestar app run with uvicorn consumes in an idling state on my machines 40-45% CPU.

Is this normal or is there a way to reduce the idling CPU consumption?

Attached a picture of cProfile. python -m cProfile -o litestar.pstats ./.venv/bin/litestar run

URL to code causing the issue

No response

MCVE

UVICORN_LOOP=uvloop litestar run                            
Using Litestar app from env: 'app.asgi:create_app'
Starting server process ────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────
┌──────────────────────────────┬──────────────────────────────────────────────────────────────────────────────────────────────────────────────┐
│ Litestar version             │ 2.2.1                                                                                                        │
│ Debug mode                   │ Disabled                                                                                                     │
│ Python Debugger on exception │ Disabled                                                                                                     │
│ CORS                         │ Enabled                                                                                                      │
│ CSRF                         │ Disabled                                                                                                     │
│ OpenAPI                      │ Enabled path=/schema                                                                                         │
│ Compression                  │ Disabled                                                                                                     │
│ Template engine              │ ViteTemplateEngine                                                                                           │
│ Static files                 │ path=/static dirs=.../src/app/domain/web/public html_mode=Enabled │
│ Middlewares                  │ JWTCookieAuthenticationMiddleware, SentryLitestarASGIMiddleware, middleware_factory                          │
└──────────────────────────────┴──────────────────────────────────────────────────────────────────────────────────────────────────────────────┘
2023-10-23T19:12:38.780745Z [info     ] Started server process [4257]  [uvicorn.error] 
2023-10-23T19:12:38.781923Z [info     ] Waiting for application startup. [uvicorn.error] 
2023-10-23T19:12:38.789916Z [info     ] Application startup complete.  [uvicorn.error] 
2023-10-23T19:12:38.792650Z [info     ] Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit) [uvicorn.error] 
^C2023-10-23T19:15:04.770399Z [info     ] Shutting down                  [uvicorn.error] 
^C2023-10-23T19:15:04.910332Z [info     ] Finished server process [4257] [uvicorn.error] 
^C2023-10-23T19:15:04.974529Z [info     ] ASGI 'lifespan' protocol appears unsupported. [uvicorn.error] 

### Steps to reproduce

```bash
- Run `litestar run`
- Look process ressources

Screenshots

Logs

No response

Litestar Version

2.2.1
python3.11

Platform

• Linux
• Mac
• Windows
• Other (Please specify in the description above)

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[provinzkraut]

I cannot reproduce this with a basic application. Can you provide a reproducible example? It’s really hard to debug this without actually know what your app looks like, but I’m fairly certain that there’s some kind of busy loop involved you’re not aware of.

[bpereto]

I can put togheter an MCVE.

in the meantime i found the culprit in the channels implementation:

litestar/litestar/channels/backends/memory.py

Line 69 in 0d4fe01

await asyncio.sleep(0)

this looping and waiting generates the CPU load.
If I disable the channels plugin or use the RedisChannelBackend with an subscription idle time of 1000 it is at the same level as running litestar without channels.

[provinzkraut]

@bpereto Thanks for the insightful report! I put up a fix over here #2547. Can you confirm this fixes your issue?