[BUG] Exit at startup failure on multiple workers

Checklist

• The bug is reproducible against the latest release and/or master.
• There are no similar issues or pull requests to fix it yet.

Describe the bug

When the startup fails, either on reload mode or multiple workers, the main process is not terminated.

To reproduce

Application:

# test.py
from fastapi import FastAPI

app = FastAPI()

@app.on_event("startup")
def startup():
    raise Exception("Hi")

uvicorn test:app --workers 2
# or
uvicorn test:app --reload

Expected behavior

All the processes (parent and children) should be terminated.

Actual behavior

❯ uvicorn test:app --reload
INFO:     Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)
INFO:     Started reloader process [40026] using watchgod
INFO:     Started server process [40028]
INFO:     Waiting for application startup.
ERROR:    Traceback (most recent call last):
  File "/home/marcelo/anaconda3/envs/uvicorn/lib/python3.8/site-packages/starlette/routing.py", line 540, in lifespan
    async for item in self.lifespan_context(app):
  File "/home/marcelo/anaconda3/envs/uvicorn/lib/python3.8/site-packages/starlette/routing.py", line 481, in default_lifespan
    await self.startup()
  File "/home/marcelo/anaconda3/envs/uvicorn/lib/python3.8/site-packages/starlette/routing.py", line 518, in startup
    handler()
  File "/home/marcelo/Development/./test.py", line 7, in startup
    raise Exception("Hi")
Exception: Hi

ERROR:    Application startup failed. Exiting.

After this log, it hangs forever. On the reload, it doesn’t prevent the failure from happening multiple times if you modify a watched file. See:

❯ uvicorn test:app --reload            
INFO:     Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)
INFO:     Started reloader process [40674] using watchgod
INFO:     Started server process [40676]
INFO:     Waiting for application startup.
ERROR:    Traceback (most recent call last):
  File "/home/marcelo/anaconda3/envs/uvicorn/lib/python3.8/site-packages/starlette/routing.py", line 540, in lifespan
    async for item in self.lifespan_context(app):
  File "/home/marcelo/anaconda3/envs/uvicorn/lib/python3.8/site-packages/starlette/routing.py", line 481, in default_lifespan
    await self.startup()
  File "/home/marcelo/anaconda3/envs/uvicorn/lib/python3.8/site-packages/starlette/routing.py", line 518, in startup
    handler()
  File "/home/marcelo/Development/./test.py", line 7, in startup
    raise Exception("Hi")
Exception: Hi

ERROR:    Application startup failed. Exiting.
WARNING:  WatchGodReload detected file change in '['/home/marcelo/Development/test.py']'. Reloading...
INFO:     Started server process [40734]
INFO:     Waiting for application startup.
ERROR:    Traceback (most recent call last):
  File "/home/marcelo/anaconda3/envs/uvicorn/lib/python3.8/site-packages/starlette/routing.py", line 540, in lifespan
    async for item in self.lifespan_context(app):
  File "/home/marcelo/anaconda3/envs/uvicorn/lib/python3.8/site-packages/starlette/routing.py", line 481, in default_lifespan
    await self.startup()
  File "/home/marcelo/anaconda3/envs/uvicorn/lib/python3.8/site-packages/starlette/routing.py", line 518, in startup
    handler()
  File "/home/marcelo/Development/./test.py", line 7, in startup
    raise Exception("Hi")
Exception: Hi

ERROR:    Application startup failed. Exiting.

In the case of multiple workers, it just hangs forever.

Environment

• OS / Python / Uvicorn version: Running uvicorn 0.14.0 with CPython 3.8.10 on Linux

[Korijn]

Just want to point out that this is still an issue on 0.17.0.post1.

[Kludex]

Yes.