power management scheduled shutdown - flakey

[Wayne Workman]

@Tom-Elliott It doesn’t need to update. It just needs to check the current date and time just before the task.

if the task was to shut down at 10 pm, and the computer tries to do that at 8 AM, how much sense does that make? None. If it simply checks the local system time, It’d know that the time was missed by too much and to skip that power task.

[Tom Elliott]

@Wayne-Workman That’s just it. The check is to see if the current time is past the time that was set.

That’s how cron’s work. You can give it a “period” of adjustment I suppose, but it isn’t going to know the difference because it’s based on the task time itself in whole.

For example. 7/27/2016 - 2200 < 7/27/2016 - 2201 (therefore it knows it has to do the action and update the next time it should run). Same goes for 7/27/2016 - 2200 and January 15, 2019 - 0000. It has to do the check to know whether to run it in the first place.

Remember, we’re not dealing with linux for the crontabs, rather services that act similar (but are not equivalent) to real crontabs.

So a grace period may be needed, but what’s a suitable one? For a minute task I suppose it doesn’t matter, but for an hourly task should you wait an hour, 5 minutes, 10 minutes, 14 seconds? You understand?

[Wayne Workman]

@Tom-Elliott I understand how it currently works, Tom. And how it’s currently working isn’t acceptable.

[Tom Elliott]

@Wayne-Workman Isn’t acceptable by who?

[Wayne Workman]

@Tom-Elliott By anyone who turns on a computer only to have it immediately shut down.

I can’t use it as it is.

[Tom Elliott]

@Wayne-Workman If you’re running power management, why not leave your systems running and let powermanagement handle it?

[Tom Elliott]

@Wayne-Workman

I think the “simplest” solution (if this is not already the case) for power management is to simply keep the management tasks in memory. So they are stored in such a way that if you shutdown the fog service, it has to recreate the new date/time. Dealing with math of timestamps would work, but is imperfect due to the nature of how the crontasks are operated. Simply by having it recheck the next run time when the service restarts is much nicer and would be completely independent to the systems.

[Wayne Workman]

@Tom-Elliott The service isn’t shutdown when a system hibernates, which is exactly how windows fast startup operates. The local host’s time needs checked every time the fog client thinks a power task should be ran - and if the local time and the task’s scheduled time match within a given window, then run the task. something like:
(Local time <= scheduled time + sleep time + 2 minutes)

[Tom Elliott]

Three approaches.

The 1st and theoretically the most simple. On service shutdown/restart (before it has stopped, but while in the processes of stopping) Remove and scheduled tasks created by the module. (which means we need a way to find out which task scheduler tasks were created by PM to begin with).

The 2nd and most simple, but could pose problem on next boot: On service start, clear out any scheduled tasks created by the service (which means we need a way to find out which task scheduler tasks were created by PM to begin with).

The 3rd, is only make powermanagement handled by the service itself. Fairly difficult to implement easily, but once done fairly fail proof. This way when unloading the service, the tasks are auto magically cleaned up (and we don’t have to manage different elements of the system as it would only care about what it’s received).

[Tom Elliott]

@Wayne-Workman Because it’s cron, you can only do a scheduled time + 2 minutes, but even still. If the system is hibernating for a “shutdown” how did you create the image?

[Wayne Workman]

@Tom-Elliott said in power management scheduled shutdown - flakey:

If the system is hibernating for a “shutdown” how did you create the image?

Good question. No idea.

[Tom Elliott]

Oh, and to add on. If you based it on the sleep time – yes I know you can change it --, may run into MANY more strange things. For Powermanagment, the checks should be every minute, regardless of Cycle checktime.

[Wayne Workman]

@Tom-Elliott I can agree on that.

[Joe Schmitt]

Issue has been fixed and the patch will be available when 0.11.5 is released.

[Wayne Workman]

@Joe-Schmitt Does this change only apply to scheduled shutdown tasks, or to all power management tasks including reboot? Just asking.