uvicorn is not checking occupied ports

[mhechthz]

I wonder why uvicorn on calling from within python

uvicorn.run("mywebapp:app",host="0.0.0.0",port=port,reload=True)

is not checking if the port is already occupied or blocked or not.

I' m forced to run something like this:

def check_port(port,host="0.0.0.0",do_exit=True):

    with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
        if do_exit:
            print(f"port {port} already in use ... exit ...")
            time.sleep(10)
            sys.exit()
        else:
            return False
return True

wich is totally inconvenient, since one obviously wants a message if runnig uvicorn will not be successsful.

Is there any chance to do this with uvicorn, e.g with an option like checkport=True?

[Kludex]

What do you mean by "is not checking"?

[Kludex]

It's doing that...

[mhechthz]

Hmmm ... I had an automatically started application that was somehow hanging that did not react to requests. I didn't realise this and started it again. Program started without complaints but no reaction on the service endpoint. After killing all processes on this port and starting the application again, all worked well. So I assume that the hanging process blocked the port but the new process did not realize this. I expected to get a warning or an error on startup.

[mhechthz]

Ok, checked it. It fails on reload=True. See image. First process inside VSCode is shadowing second (new) process, so if it hangs, there is no message and no reaction.