why do i have error "Address already in use"?

Question

i run my flask app, and it works good, but by the time the app is stopped and in my uwsgi log

probably another instance of uWSGI is running on the same address (127.0.0.1:9002).
    bind(): Address already in use [core/socket.c line 764]

when i run touch touch_reload, app is working again. I run anything else on the server which may take the socket.

my conf:

nginx
server {
    listen 80;
    ....
    location / {
       include uwsgi_params;
       uwsgi_pass 127.0.0.1:9001;
    }
    ....
}
server {
    listen 80;
    ....
    location / {
       include uwsgi_params;
       uwsgi_pass 127.0.0.1:9003;
    }
    ....
}

uwsgi:
chdir = /var/www/../
module = wsgihandler
socket = 127.0.0.1:9003
wsgi-file = app/__init__.py
callable = app
master = true
chmod-socket = 664
uid = root
gid = root
processes = 4
socket-timeout = 180
post-buffering = 8192
max-requests = 1000
buffer-size = 32768
logto = /var/www/.../log/uwsgi.log
touch-reload = /var/www/.../touch_reload

Answer 1

maybe you stop uwsgi by crtl + z:

1. find the pid of process which take 8000

$ lsof -i:8000

result maybe is:

COMMAND  PID       USER   FD   TYPE ...
uwsgi   9196       xxx    4u  xxx   ...

then

$ kill 9196