Distributors ponder a systemd change

Posted Jun 8, 2016 9:21 UTC (Wed) by matthias (subscriber, #94967)
In reply to: Distributors ponder a systemd change by diegor
Parent article: Distributors ponder a systemd change

sighup is not working (at least not all the times). Every program that has some cleanup to do before exiting is intercepting sighup (it has to). If the shutdown of the program fails, it is left running. I have seen such processes hanging around forever, possibly using 100% of CPU time.

Also what is the difference if systemd kills you process or the launcher process of the gui? There has to be an opt-out for screen, tmux and nohup in both cases.

Distributors ponder a systemd change

Posted Jun 8, 2016 11:56 UTC (Wed) by ras (subscriber, #33059) [Link] (3 responses)

> sighup is not working (at least not all the times).

I remember I have had a process going infinite on logout, but can't actually recall when - it was a long time ago. Infinite loops after getting a sighup must be easy to track down.

What I can recall happening recently is a kernel driver misbehaving. I go through the rmmod, modprobe dance. But instead of fixing it the processes using the driver hangs on some unbreakable kernel lock, and the eventual kill -9 is a complete waste of time. The only way out is a reboot of a production machine. I gather race conditions during module removal are unavoidable, and regardless there always seems to be more of them. If the systemd or gnome guys have a fix for this, no matter how bad, I promise to call it a thing of beauty.

But using this sledge hammer to cure a simple infinite loop bug, and break backward compatibility - sorry, no.

Distributors ponder a systemd change

Posted Jun 8, 2016 13:51 UTC (Wed) by bronson (subscriber, #4806) [Link] (1 responses)

Since processes surviving logout has been a problem for decades, it seems like the infinite loops are not so easy to track down after all?

Distributors ponder a systemd change

Posted Jun 8, 2016 22:03 UTC (Wed) by Cyberax (✭ supporter ✭, #52523) [Link]

Not if they happen in a subset of conditions. For example, if you have an encrypted home directory that is lazily unmounted after the logout.

Distributors ponder a systemd change

Posted Jun 8, 2016 14:51 UTC (Wed) by diegor (subscriber, #1967) [Link]

But if not even kill -9 can kill it, systemd can't kill it too.

Usually process for which kernel is serving a system call, can not be interrupted, until kernel have finished.