Run uvicorn with multiple workers on Windows - WinError 5

[grays820]

from starlette.applications import Starlette
from starlette.responses import JSONResponse
import uvicorn

app = Starlette(debug=True)

@app.route('/')
async def homepage(request):
return JSONResponse({'hello': 'world'})

@app.route('/long')
async def longpool(request):
z = 0
for x in range(1000000):
z = z+1
print(z)
return JSONResponse({'hello11': 'world'})

if name == 'main':
uvicorn.run(app, host='0.0.0.0', port=8000,workers=2)

error:

�[33mWARNING�[0m: You must pass the application as an import string to enable 'reload' or 'workers'.
�[32mINFO�[0m: Uvicorn running on �[1mhttp://0.0.0.0:8000�[0m (Press CTRL+C to quit)
�[32mINFO�[0m: Started parent process [�[36m�[1m40920�[0m]
Traceback (most recent call last):
File "main.py", line 29, in
uvicorn.run(app, host='0.0.0.0', port=8000,workers=2)
File "C:\Users\grays\Envs\python3\lib\site-packages\uvicorn\main.py", line 310, in run
supervisor.run(server.run, sockets=[sock])
File "C:\Users\grays\Envs\python3\lib\site-packages\uvicorn\supervisors\multiprocess.py", line 59, in run
process.start()
File "c:\python37\Lib\multiprocessing\process.py", line 112, in start
self._popen = self._Popen(self)
File "c:\python37\Lib\multiprocessing\context.py", line 322, in _Popen
return Popen(process_obj)
File "c:\python37\Lib\multiprocessing\popen_spawn_win32.py", line 65, in init
reduction.dump(process_obj, to_child)
File "c:\python37\Lib\multiprocessing\reduction.py", line 60, in dump
ForkingPickler(file, protocol).dump(obj)
AttributeError: Can't pickle local object 'request_response..app'

(python3) C:\Users\grays\Documents\Workspace\MyProjects\AnyTest>Traceback (most recent call last):
File "", line 1, in
File "c:\python37\Lib\multiprocessing\spawn.py", line 99, in spawn_main
new_handle = reduction.steal_handle(parent_pid, pipe_handle)
File "c:\python37\Lib\multiprocessing\reduction.py", line 87, in steal_handle
_winapi.DUPLICATE_SAME_ACCESS | _winapi.DUPLICATE_CLOSE_SOURCE)
PermissionError: [WinError 5] 拒绝访问。

already run cmd with Administrator mode

windows 10
uvicorn 0.10.4
starlette 0.12.13

[tomchristie]

The initial warning is the relevant part here: "You must pass the application as an import string to enable 'reload' or 'workers'."

Really we ought to be quitting uvicorn, rather than allowing it to run to failure after that message. (And change it from a warning to an error.)

You'll need to use the following style instead...

# If the application is `app` in module `example.py` -> Use "example:app"
uvicorn.run("example.app", host='0.0.0.0', port=8000,workers=2) 

[tomchristie]

Incidentally, are you seeing "�[0m" or proper terminal colours in the logs?

[grays820]

The initial warning is the relevant part here: "You must pass the application as an import string to enable 'reload' or 'workers'."

Really we ought to be quitting uvicorn, rather than allowing it to run to failure after that message. (And change it from a warning to an error.)

You'll need to use the following style instead...

# If the application is `app` in module `example.py` -> Use "example:app"
uvicorn.run("example.app", host='0.0.0.0', port=8000,workers=2) 

tks，i change code like
uvicorn.run("main:app", host='0.0.0.0', port=8000,workers=2)
now it raise OSError: [WinError 10022]

[tomchristie]

Looks to me like this should be closed via #487. Now released as 0.10.6.

Let me know how that goes.

[grays820]

Looks to me like this should be closed via #487. Now released as 0.10.6.

Let me know how that goes.

i upgrade to 0.10.8,the error change to [WinError 10022],orz..

[ghostzero192]

@grays820 try this workaround:

if __name__ == "__main__":
    uvicorn.run("main:app", host='127.0.0.1', port=8000, workers=8, debug=True)

it should work, aparently the debug is set to False by default and this is what is causing the error

[grays820]

@grays820 try this workaround:

if __name__ == "__main__":
    uvicorn.run("main:app", host='127.0.0.1', port=8000, workers=8, debug=True)

it should work, aparently the debug is set to False by default and this is what is causing the error

yes，set debug=True，it work fine，why not support debug=False?

[cgi1]

Getting the same error message when trying to start a FastAPI application here

[WhitehatLaksh]

The initial warning is the relevant part here: "You must pass the application as an import string to enable 'reload' or 'workers'."

Really we ought to be quitting uvicorn, rather than allowing it to run to failure after that message. (And change it from a warning to an error.)

You'll need to use the following style instead...

# If the application is `app` in module `example.py` -> Use "example:app"
uvicorn.run("example.app", host='0.0.0.0', port=8000,workers=2) 

Not working

[larpig]

Hey @WhitehatLaksh ,

Indeed, such an approach it is not working. You should try the approach proposed on [BUG] uvicorn can not start FastAPI with example settings, which is:

import uvicorn
from fastapi import FastAPI

app = FastAPI()


@app.get("/")
def get_root():
    return {"message": "Hello World"}


if __name__ == "__main__":
    uvicorn.run("__main__:app", host="0.0.0.0", port=8000, reload=True, workers=2)