My script to record all played steemmonster games from https://beempy.com froze:
I restarted the script (I'm using systemctl for this) and it is now catching up.
How to prevent a frozen script
There was no bug, it just froze. This happend already before and I will now try to fix this.
I'm thinking of restarting the systemctl service every day. By this, a frozen script can only lead to a maximum stop of 24 hours.
Possible ideas to implement this:
- cron job with a systemctl restart service_name
- systemctl timer with a systemctl restart service_name
- Using
RuntimeMaxSec
Cron job
A new rule can be entered by:
sudo crontab -e
The new rule could look like:
0 0 * * * /bin/systemctl restart yourService
systemctl timer
We need two files, one restart_service.timer
[Unit]
Description=Do something daily
[Timer]
OnCalendar=daily
Persistent=true
[Install]
WantedBy=timers.target
and a restart_service.service:
[Unit]
Description=Restart service
[Service]
Type=oneshot
ExecStart=/usr/bin/systemctl try-restart my_program.service
They have to be copied to /etc/systemd/system and can be started by:
systemctl enable --now restart_service.timer
RuntimeMaxSec
When systemctl is newer than version 229, this is a good solution. The version can be found out by:
systemctl --version
The manual says about RuntimeMaxSec:
Configures a maximum time for the service to run. If this is used and the service has been active for longer than the specified time it is terminated and put into a failure state. Note that this setting does not have any effect on Type=oneshot services, as they terminate immediately after activation completed. Pass "infinity" (the default) to configure no runtime limit.
This seems to be exactly what I need.
Restart and RuntimeMaxSec has to be added to the service file in the [Service] part:
[Service]
Restart=always
RuntimeMaxSec=10800
This works for my scripts as they do not run forever. I'm using RestartSec to restart the script when it is finished.
Conclusion
RuntimeMaxSec seems to me a good measure to robustify systemctl scripts. I will try this on my systemctl services.