[systemd-devel] Timers and Service Conditions

[Merten Sach]

Hi,

I am running version 216. I will try to reproduce it using a newer version when
I got some spare time.

I tried to reproduce it and I had, at first, some problems. But here are the
steps that I used:

* Enable autobackup at merten.timer
* Restart system with AC connected
* Let the timer activate once
* Disconnect AC
* Wait for next timer trigger

After the timer elapsed the dbus-daemon fully utilizes the CPU with messages
like the following:

signal sender=:1.0 -> dest=(null destination) serial=5611797
path=/org/freedesktop/systemd1/unit/autobackup_40merten_2etimer;
interface=org.freedesktop.DBus.Properties; member=PropertiesChanged
   string "org.freedesktop.systemd1.Timer"
   array [
      dict entry(
         string "NextElapseUSecRealtime"
         variant             uint64 0
      )
      dict entry(
         string "NextElapseUSecMonotonic"
         variant             uint64 1671969806
      )
      dict entry(
         string "LastTriggerUSec"
         variant             uint64 1432119664109599
      )
      dict entry(
         string "LastTriggerUSecMonotonic"
         variant             uint64 1820165195
      )
      dict entry(
         string "Result"
         variant             string "success"
      )
   ]
   array [
      string "TimersMonotonic"
      string "TimersCalendar"
   ]



Attached you find the service and timer units that I used.

Thanks


On 19/05/15 16:57, Lennart Poettering wrote:
> On Thu, 02.04.15 12:01, Merten Sach (merten at tabinin.eu) wrote:
> 
>> Hi,
>>
>> I have a problem with a timer that trigges a service that has a condition set.
>> The timer defines the following properties:
>>
>>   [Timer]
>>   OnBootSec=1h
>>   OnUnitInactiveSec=1h
>>   Unit=autobackup@%i.service
>>
>> The service unit set the following condition:
>>
>>   ConditionACPower=true
>>
>> When I'm now on AC power the service is never active and, therefor, the inactive
>> timestamp is never set. This causes the timer to be triggered repeatedly which
>> causes a very high system load.
>>
>> I want to keep the timer relative to bootup. So, can I avoid OnCalendar= ?
> 
> Hmm, so I tried to reproduce this issue here, bu I couldn't. I used
> the same unit files as you propose, but this works cleanly, as the
> code already contains checks that if the triggered unit doesn't have
> an initialized inactive timestamp we'll fall back to the last trigger
> time of the unit. And if that's not set, we'll simply not set any
> timer...
> 
> Hence, which version of systemd did you run this into with?
> 
> Any chance you can check if you can reproduce this with current git or
> at least 219?
> 
> Lennart
> 

-------------- next part --------------
[Unit]
Description=autobackup service
Documentation=
Wants=avahi-daemon.socket
ConditionACPower=true

[Service]
Type=simple
User=%i
ExecStart=/usr/bin/true
#ExecStart=/usr/local/bin/autobackup
-------------- next part --------------
[Unit]
Description=autobackup timer
Documentation=

[Timer]
OnBootSec=3m
OnUnitInactiveSec=3m
Unit=autobackup@%i.service

[Install]
WantedBy=multi-user.target