detect and possibly cancel idle interactive apps.

[johrstrom]

Cleaning out discourse - this has come up a few times:
https://discourse.openondemand.org/t/detect-idle-sessions/741
https://discourse.openondemand.org/t/timeout-count-down-on-connection-link-to-permit-idle-job-timeout-before-the-user-requested-timelimit/2836

At the time of writing, this would be very very difficult. Maybe if we have something proxying for us on the compute node may help, but actually detecting on the web server what's happening on the compute node is an arduous task. Possibly solved through files on the NFS?

Even if we do have a mechanism to communicate this data, the web node may not be able to catch this because itself is being shut down because it's idle. So there's a window where we have to catch this after the job starts, but before the PUN itself is shutdown due to inactivity. I guess that best effort is better than nothing?