[systemd-devel] [RFC] core: introduce ExitOnIdle= and ExitOnIdleSec=

[Kyungmin Park]

On Tue, Apr 21, 2015 at 12:10 AM, Lennart Poettering
<lennart at poettering.net> wrote:
> On Mon, 20.04.15 23:56, WaLyong Cho (walyong.cho at samsung.com) wrote:
>
>> If a service does not consume CPU during some time(can be configured
>> by ExitOnIdleSec=) and set to stopped on idle state(ExitOnIdle=), the
>> service will be stopped. This can be useful if the service provides
>> some of activation methods.
>
> Hmm, I am not convinced this would be a good idea, sorry.
>
> The crux of the issue is that it is really hard to detect from the
> outside if a daemon is really idle. Only the daemon itself knows
> whether it is truly idle or not. I mean, it could just be waiting for
> some timer to elapse, or some other external event.
>
> I doubt this is really useful unless you have really really simple
> daemons that purely react on client requests and nothing else, and you
> know the codebase and that it is OK to terminate the daemon just
> because its CPU usage is zero. But if you know the codebase that well
> it would probably be a better idea to just add support for
> exit-on-idle directly to the daemon in question.
>
> exit-on-idle is really something that should be implemented *in* the
> daemon, and not done externally!

then how about to change the concept? IdleNotifier?
some daemon users said it's hard to know how long its idle so systemd
give idle time by notification.
It will save lots of codes. don't need to implement own timer for idle timeout.

it's match your comments. "It should be implemented *in* the daemon".
when idle notification is comes. daemon decides exit or not. Of course
daemon will implement defined idle notifier callback.

does it reasonable?

Thank you,
Kyungmin Park