ffsuspend 0.1

Suspend processes when X window not visible (i3-wm only)

FFSuspend

A small script to monitor processes and i3 events in order to SIGSTOP GUI processes when their X windows are not on a visible i3 workspace.

But WHY?!

I'm travelling a lot by train and use that time to work on stuff on my laptop. I tend to keep open some programs, like a browser with some documentation or library reference. However some programs, after being used for a while, tend to consume up to one CPU core just for idling (looking at you, firefox), which significantly lowers battery life and brings me in the uncomfortable situation to have a constantly warm computer on my lap. So instead of tackling the root cause, I went for the easiest route and this script is the result of that.

Dependencies

This is a hacky script that defers much of its functions by parsing the output of some utility programs. These need to be installed for it to work:

• i3-msg
• killall
• ps
• xdotool
• xsel

Caveats / Disclaimer

The X clipboard protocol is an IPC protocol that talks to the current owner of the clipboard, whenever its contents is requested. If this process is SIGSTOPed, applications tend to freeze indefinitely, whenever trying to read the clipboard contents.

While there is probably a cleaner solution, FFSuspend has a hacky feature that monitors clipboard contents and skips one cycle of stopping a process, when the clipboard was changed while that process' window was visible. This can be enabled with the -c commandline flag.

There may be other 'interesting' sideeffects when SIGSTOPing processes, so be wary and use at your own risk.

License

FFSuspend is licensed under the GPLv3 or later, see LICENSE.txt.