Lifespan error hangs system

[dineshbvadhia]

Python 3.11+
FastAPI 0.111
Windows 11 Pro (23H2)

Simulating an error in lifespan (entry) causes the system to hang after the last ERROR message. In this case, I want the program to exit. What is wrong here?

# life.py

import logging
from contextlib import asynccontextmanager
from fastapi import FastAPI
import structlog

logger = structlog.get_logger()

@asynccontextmanager
async def lifespan(app: FastAPI):
    try:
        print('entry')
        print(1/0)
    except Exception as exc:
        logger.exception(exc)
        sys.exit(1)
    yield
    print('exit')
    
app = FastAPI(lifespan=lifespan)

if __name__ == "__main__":
    import uvicorn
    uvicorn.run(
        "life:app",
        host="0.0.0.0",
        port=8000,
        log_level="debug",
        reload=True,)

entry
{"event":"ZeroDivisionError('division by zero')","level":"error","exception":"Traceback (most recent call last):\n  File \life.py\", line 39, in lifespan\n    print(1/0)\n          ~^~\nZeroDivisionError: division by zero","timestamp":"2024-06-08T08:21:19.870540Z"}
ERROR:    Traceback (most recent call last):
  File "life.py", line 39, in lifespan
    print(1/0)
          ~^~
ZeroDivisionError: division by zero

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "... starlette\routing.py", line 732, in lifespan
    async with self.lifespan_context(app) as maybe_state:
  File "... contextlib.py", line 204, in __aenter__
    return await anext(self.gen)
           ^^^^^^^^^^^^^^^^^^^^^
  File "life.py", line 42, in lifespan
    sys.exit(1)
SystemExit: 1

ERROR:    Application startup failed. Exiting.

[chyok]

Hi @dineshbvadhia ,
set reload to False, and it will exit.

[dineshbvadhia]

Sorry for the late response. Setting reload=False fixed the hanging problem. Thanks.

The next problem: On error a sys.exit() is executed which should exit the program without displaying a Traceback. But, it does. A raise SystemExit() also displays the Traceback. I cannot work out if the problem lies within the lifespan code, Starlette or uvicorn. Any thoughts?

[dineshbvadhia]

Ah, the Traceback is displayed because the log_level is set to debug.