[mythtv] backend from SVN 9761 bangs on mysqld

Janne Grunau janne-mythtv at grunau.be
Sun Apr 23 15:32:31 UTC 2006

On Saturday 22 April 2006 18:24, Daniel Kristjansson wrote:
> On Sat, 2006-04-22 at 09:18 +0200, Tino Keitel wrote:
> > Hi folks,
> >
> > after I installed SVN 9761 I noticed that mysqld frequently uses
> > all available CPU time when the backend is running. The last
> > version I had was SVN 9591, where this wasn't the case. I ran the
> > backend with -v eit and got this message when mysqld was using 100&
> This is probably normal. The DB hit is for the resceduling query.
> Sometimes if the DB is corrupted this query will take much longer
> than normal, but the recorder can handle a pretty substantial query
> when the DB is not corrupted.

It is not the scheduler alone. One of the recent EIT-refactoring (iirc 
9671) adds noticeable DB-load.
The main  reason is probably that we reinsert the event even if we have 
a perfect match of stored event and broadcastet event. That's alone not 
the problem but due the current limitations of the eit-cache all events 
gets reinserted for every channel change.
A 'if (match == 12000) return 0;' in UpdateDB(MSqlQuery, int) reduces 
the number of inserted events and the DB load significantly (together 
with other changes).

I reported nothing of this since it will be mostly solved if the event 
cache is persistant per backend run. For the rest I'll create a ticket.


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