[mythtv-users] anacron time change after upgrade to Ubuntu 18.04

Wed Nov 7 16:57:23 UTC 2018

On 11/7/18 11:43 AM, Stephen Worthington wrote:
> On Wed, 7 Nov 2018 06:45:17 -0500, you wrote:
>
>> On 11/6/18 9:59 AM, Stephen Worthington wrote:
>>> On Tue, 6 Nov 2018 09:39:12 -0500, you wrote:
>>>
>>>> On 11/6/18 7:46 AM, Stephen Worthington wrote:
>>>>> On Tue, 6 Nov 2018 06:59:31 -0500, you wrote:
>>>>>
>>>>>> On my backend I have 2 cron jobs I put into /etc/cron.daily for database
>>>>>> backup and optimization. The scripts email when done with the date and time.
>>>>>>
>>>>>> On Ubuntu 16.04 it ran around 7:35 am. After the 'do-release-upgrade' it
>>>>>> runs at 12:10 am.
>>>>>>
>>>>>> I always wondered why 7:35am with a /etc/crontab entry like the one
>>>>>> below, but I really can't figure out 12:10 am based on it.
>>>>>>
>>>>>> Any ideas?
>>>>>>
>>>>>> 25 6    * * *    root    test -x /usr/sbin/anacron || ( cd / &&
>>>>>> run-parts --report /etc/cron.daily )
>>>>>>
>>>>>> Jim A
>>>>> If you read that crontab code carefully, you will see that what it is
>>>>> doing is testing to see if an anacron executable is present, and if
>>>>> so, it does not run the cron.daily tasks from crontab.  As Ubuntu does
>>>>> have an anacron executable present, those crontab entries do nothing,
>>>>> and it is left to anacron to run the /etc/cron.daily, /etc/cron.weekly
>>>>> and /etc/cron.monthly tasks.  The /etc/cron.hourly tasks, however are
>>>>> run from crontab.
>>>>>
>>>>> In Ubuntu 18.04, anacron is now run from systemd.  There are two
>>>>> systemd units:
>>>>>
>>>>> /lib/systemd/system/anacron.service
>>>>> /lib/systemd/system/anacron.timer
>>>>>
>>>>> The main unit that actually runs anacron is anacron.service.  The
>>>>> anacron.service unit is run when the PC starts up (as long as mains
>>>>> power is available) and when it wakes up from a sleep mode.  The
>>>>> anacron.timer unit runs anacron.service every hour, and
>>>>> anacron.service runs anacron.  Here is what is in those two unit
>>>>> files:
>>>>>
>>>>> root at mypvr:/lib/systemd/system# cat anacron.service
>>>>> [Unit]
>>>>> Description=Run anacron jobs
>>>>> After=time-sync.target
>>>>> ConditionACPower=true
>>>>> Documentation=man:anacron man:anacrontab
>>>>>
>>>>> [Service]
>>>>> ExecStart=/usr/sbin/anacron -dsq
>>>>> IgnoreSIGPIPE=false
>>>>>
>>>>> [Install]
>>>>> WantedBy=multi-user.target
>>>>> root at mypvr:/lib/systemd/system# cat anacron.timer
>>>>> [Unit]
>>>>> Description=Trigger anacron every hour
>>>>>
>>>>> [Timer]
>>>>> OnCalendar=hourly
>>>>> RandomizedDelaySec=5m
>>>>> Persistent=true
>>>>>
>>>>> [Install]
>>>>> WantedBy=timers.target
>>>>>
>>>>> So in 18.04, you will get the cron.{daily,weekly,monthly} jobs being
>>>>> run about 5 minutes after the PC starts up, and after that at about 5
>>>>> past midnight.  The 5 minutes bit is because after anacron it started,
>>>>> it wait 5 minutes before it does anything.  That is very useful as it
>>>>> allows you to kill the anacron task immediately after you reboot your
>>>>> MythTV box, so it will then run anacron at the usual time instead of
>>>>> immediately.  You only need to kill anacron if the day has changed
>>>>> since anacron was last run, as anacron uses timestamps stored in files
>>>>> in /var/spool/anacron to tell it when its jobs were last run and will
>>>>> not run them again on the same day (or week or month).  The time that
>>>>> anacron gets run at has a variable extra delay of up to 5 minutes
>>>>> because of the "RandomizedDelaySec=5m" line in anacron.timer.  So
>>>>> anacron will run its tasks 5 minutes after boot, and 5-10 minutes
>>>>> after the hour after the day changes ie 5-10 minutes after midnight.
>>>>>
>>>>> In earlier Ubuntu versions, before anacron was run from systemd, it
>>>>> was run from cron using the file /etc/cron.d/anacron.  That started
>>>>> anacron at 07:30.  Now, the /etc/cron.d/anacron file will only run
>>>>> anacron if systemd is not being used.
>>>>>
>>>>> I found the change in timing from 07:30 to midnight to be a big
>>>>> problem.  I have a huge database, and my backup and database check
>>>>> jobs take over half an hour, during which mythfrontend is not very
>>>>> usable for long periods.  And if I have more than one recording
>>>>> happening, I can get bad recordings.  Since I often have multiple
>>>>> recordings happening at midnight, and I am also likely to be watching
>>>>> a programme, it was very annoying to have anacron running then.  So I
>>>>> have changed anacron back to being run at 07:30 only.  I consider that
>>>>> anacron being run every hour is actually a bug - it does not run the
>>>>> cron.hourly jobs, so it only needs to be run once a day.
>>>>>
>>>>> To change it back to how it used to be, I created a systemd override
>>>>> file for anacron.timer:
>>>>>
>>>>> root at mypvr:/etc/systemd/system# ll -d ana*
>>>>> drwxr-xr-x 2 root root 4096 Oct 21 01:13 anacron.timer.d/
>>>>> root at mypvr:/etc/systemd/system# cd anacron.timer.d/
>>>>> root at mypvr:/etc/systemd/system/anacron.timer.d# ll
>>>>> total 12
>>>>> drwxr-xr-x  2 root root 4096 Oct 21 01:13 ./
>>>>> drwxr-xr-x 27 root root 4096 Oct 23 23:45 ../
>>>>> -rw-r--r--  1 root root  166 Oct 21 01:13 anacron-timer-override.conf
>>>>> root at mypvr:/etc/systemd/system/anacron.timer.d# cat
>>>>> anacron-timer-override.conf
>>>>> [Unit]
>>>>> Description=Trigger anacron at 07:30, as happened before the Ubuntu
>>>>> 18.04 upgrade.
>>>>>
>>>>> [Timer]
>>>>> OnCalendar=
>>>>> OnCalendar=07:30
>>>>> RandomizedDelaySec=0s
>>>>> Persistent=true
>>>>>
>>>>> If you want to create an override file like mine, the easy way is to
>>>>> do this command:
>>>>>
>>>>> sudo systemctl edit anacron.timer
>>>>>
>>>>> and paste my override file into it.  The systemctl edit command is
>>>>> only available in newer versions of systemd, but it is very useful as
>>>>> it sets up the override directory and .conf file with the right
>>>>> ownership and permissions automatically.
>>>>>
>>>>> I have filed a bug report about this problem, but I have not had any
>>>>> response to it yet:
>>>>>
>>>>> https://bugs.launchpad.net/ubuntu/+source/anacron/+bug/1799361
>>>> This is a great explanation and very helpful.  I've duplicated what you
>>>> did and will look for the changes to take affect tomorrow.
>>>>
>>>> Thanks,
>>>>
>>>> Jim A
>>> You can check to see what is going to happen by using:
>>>
>>> sudo systemctl status anacron.timer
>>> sudo systemctl status anacron
>> Well something went wrong. Both jobs ran a 12:07AM install of 7:35AM.
>>
>> It's now about 6:35AM.
>>
>> I just ran the 2 systemctl commands and their output is below:
>>
>> jim at mythbuntu:~$*sudo systemctl status anacron.timer*
>> [sudo] password for jim:
>> ? anacron.timer - Trigger anacron at 07:30, as happened before the Ubuntu
>>     Loaded: loaded (/lib/systemd/system/anacron.timer; bad; vendor
>> preset: enable
>>    Drop-In: /etc/systemd/system/anacron.timer.d
>>             ??override.conf
>>     Active: active (waiting) since Tue 2018-11-06 15:36:31 EST; 15h ago
>>    Trigger: Wed 2018-11-07 07:01:40 EST; 24min left
>>
>> Nov 06 15:36:31 mythbuntu systemd[1]: Started Trigger anacron at 07:30,
>> as happe
>> Nov 07 06:37:18 mythbuntu systemd[1]:
>> /etc/systemd/system/anacron.timer.d/overri
>> jim at mythbuntu:~$
>> jim at mythbuntu:~$ *sudo systemctl status anacron*
>> ? anacron.service - Run anacron jobs
>>     Loaded: loaded (/lib/systemd/system/anacron.service; enabled; vendor
>> preset:
>>     Active: inactive (dead) since Wed 2018-11-07 06:05:27 EST; 33min ago
>>       Docs: man:anacron
>>             man:anacrontab
>>    Process: 7771 ExecStart=/usr/sbin/anacron -dsq (code=exited,
>> status=0/SUCCESS)
>>   Main PID: 7771 (code=exited, status=0/SUCCESS)
>>
>> Nov 07 06:05:27 mythbuntu systemd[1]: Started Run anacron jobs.
>> Nov 07 06:05:27 mythbuntu anacron[7771]: Anacron 2.3 started on 2018-11-07
>> Nov 07 06:05:27 mythbuntu anacron[7771]: Normal exit (0 jobs run)
>> jim at mythbuntu:~$
>>
>> I got some advice from the Ubuntu forum to not use anacron for precise
>> timing stuff but use cron.  I've haven't explored what that person meant.
>>
>> "That doesn't alter anacron's behavior of only supporting 24 hour
>> resolution in jobs.
>>
>> If you need control to the minute, use cron."
>>
>> Jim A
> Anacron is still being run every hour, according to the results of the
> status commands.  So it looks like the systemctl edit command did not
> do everything necessary for the new override to take effect.  Please
> do these commands and see if anacron.timer is then scheduled for
> 07:30:
>
> sudo systemctl stop anacron.timer
> sudo systemctl daemon-reload
> sudo systemctl start anacron.timer
> sudo systemctl status anacron.timer
> sudo systemctl status anacron

at this point I have been convinced that I should just leave the anacron 
stuff as it shipped from the factory and not mess with it.

I'm going to play with 2 methods over the next few nights to see which 
works, maybe both will.

1. only have my database scripts in /home/jim/ and add one entry to 
/etc/crontab:

         25 6    * * *    root    /home/jim/optimize_mythdb ; 
/home/jim/mythtv-backup

2. sudo crontab -e

         25 6    * * *    /home/jim/optimize_mythdb ; 
/home/jim/mythtv-backup