CODEWITHSUNDEEP
pythonlinuxbashssh
Mike Mishkin
Mike Mishkin

Reputation: 336

Python process suspends on SSH logout after nohup/screen

I have a remote server through Blue Host that's intended to run a server based on Twisted for Python. The only access I have to it is over SSH, so to keep Python running after I log out I tried using nohup python server.py & and screen -dm python server.py, getting the same results for each. Everything works fine until I log out of SSH - even though Python is running in the background as expected, once I've logged out, my client can no longer communicate with the server. The strange part is that if I log back in over SSH and check the running processes with ps aux, I see Python running and my client can successfully communicate with the server again. Even if I don't type anything at all once I log back in, everything works as expected. But, of course, as soon as I log back out, it's as if the server is gone.

I've contacted support for the hosting service in case this is some oddity on their end, but hopefully this is something that can be resolved on my end instead.

Edit: Looks like Blue Host doesn't want me doing server-y stuff without buying the VPS upgrade so it looks like that's the big problem.

Edit 2: Okay, so in case anybody ends up having a similar problem, here's what the main issue turned out to be. I was mistaken in my original description; I was able to connect to the server but I was getting kicked off immediately for what turned out to be a MySQL error. I guess trying to connect to a localhost database with no active connection somehow causes problems, so instead I changed the MySQL connection command to connect to my site's IP address instead, even though it was the same IP as the server. That seemed to do the trick in terms of my main issue.

Upvotes: 0

Views: 732

Answers (1)

Martin Konecny
Martin Konecny

Reputation: 59671

Don't use this method to keep the server process running. Instead try using supervisor (apt-get install supervisor). It allows you to daemonize your process, and ability to stop/restart etc.

Here's a sample config entry (/etc/supervisor/supervisord.conf):

[program:my_server]
command=python /path/to/server/server.py
directory=/path/to/server/
autostart=true
autorestart=true
stdout_logfile=/var/log/server.log
stderr_logfile=/var/log/server_error.log
user=your_linux_user_name

After you edit your config, do

sudo service supervisor stop
sudo service supervisor start #need to do this - doing a `restart` doesn't reload the config file!

your server should now be running properly. You can manage its lifecycle via sudo supervisorctl

Upvotes: 3

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