[mythtv] Mythfilldatabase and Shepherd (tv_grab_au)

Michael T. Dean mtdean at thirdcontact.com
Mon Jul 18 20:01:31 UTC 2011

On 07/16/2011 05:17 PM, Max Barry wrote:
> I was asked to post here regarding why Shepherd (tv_grab_au) relies on
> the '--graboptions' arg that was recently removed from mythfilldatabase:
> http://code.mythtv.org/trac/ticket/9853
> Specifically, I was asked why Shepherd sets up a custom cron job on the
> user's system to call mythfilldatabase, rather than relying on MythTV's
> in-built scheduling system.
> Firstly, I should say that we have a workaround now, so this is not a
> request to keep --graboptions or anything. We can deal with that fine.
> I'm just responding to stuartm's request for info.
> So: there are a few reasons. Some may be obsolete now, because Shepherd
> was written years ago and I haven't followed MythTV's development very
> closely. But at the time, at least, this is why:
> (1) By default, MythTV triggers mythfilldatabase at 2am.

"Automatically run mythfilldatabase" defaults to enabled
"mythfilldatabase run frequency (days)" defaults to 1 (daily runs)
"mythfilldatabase execution start" defaults to 2
"mythfilldatabase execution end" defaults to 5

which leaves a 3hr window to run mythfilldatabase.  Coupled with:

>   Shepherd phones
> home with stats, and our graphs were showing an order of magnitude spike
> in usage at 2am, as a great many Shepherd users Australia-wide all hit
> the datasources at once. Please bear in mind that each Shepherd user is
> not simply downloading one XMLTV file, but rather compiling XMLTV by
> scraping dozens or hundreds or thousands of different web pages.


runs should be spread out within that window.

That said, I'm all for changing the defaults for execution start and end 
to 0/23 (meaning it's allowed to run at any time of day--so runs would 
be spread out over the whole day, where each would be "seeded" by the 
time the user first ran mythbackend).  I'd prefer to see 
mythfilldatabase configured to just work when users run 
mythbackend--without having to realize there's a buried setting that 
limits it to only run in a small time period.  Then, any users who 
choose inappropriate/underpowered systems to run the master backend 
and/or database server can find the settings and limit the run.  IMHO, 
we should default to a configuration that assumes properly-spec'ed 
systems.  :)

> (2) MythTV assumes it will be powered on for the scheduled MFDB run, and
> if it's not--e.g. it's a system that shuts down when idle--it skips that
> day. Users could thus see a dwindling supply of guide data "days" and
> think something was wrong with Shepherd. It's a particular problem when
> combined with (1) above, because systems that auto-poweroff are often
> off at 2am.
> (This seems like a universal problem, not Australia-specific, so very
> possibly it's been addressed since I last looked at it.)


I'll let someone else respond to the other issues.


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