[Beowulf] Users abusing screen

Bogdan Costescu bcostescu at gmail.com
Wed Oct 26 08:41:50 PDT 2011


On Fri, Oct 21, 2011 at 15:10, Prentice Bisbal <prentice at ias.edu> wrote:
> Periodically, when I have to shutdown/reboot a system for maintenance,
> I find a LOT of shells being run through the screen command for users
> who aren't logged in. The majority are idle shells, but many are running
> jobs, that seem to be forgotten about.
> ...
> I would like to remove screen from my environment entirely to prevent
> this.

>From what I understand from your message, it's not screen per-se which
upsets you, it's the way it is (ab)used by some users to start long
running memory hogging jobs; you seem to be OK with idle shells found
at maintenance time which are still started through screen. So why the
backlash against screen ?

Starting jobs in the background can be done directly through the
shell, with no screen; if the job can be split in smaller pieces
time-wise, they can be started by at/cron; screen can be installed by
a user, possible under a different name... so many and surely other
possibilities to still upset you even if you uninstall screen, because
you focus on the wrong subject. To deal with forgotten long running
jobs, you have various administrative (f.e. bill users/groups, even if
in some kind of symbolic way) or technical (f.e. only allow 24h CPU
time through system-wide limits or install a daemon which watches and
warns and/or takes measures) means - some of these have been discussed
on this very list in the past or have been mentioned earlier in this
thread. Each situation is different (f.e. some legitimate jobs could
run for more than 24h), so you should check all suggestions and apply
the one(s) which fit(s) best. I know from my own experience that it's
not easy to be on this side of the fence :-)

Good luck!
Bogdan


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