[mythtv-users] slow mythweb?

Udo van den Heuvel udovdh at xs4all.nl
Mon Apr 21 15:09:21 UTC 2008

Jens Baumeister wrote:
>> I get this:
>> mysql> show processlist;
>> (at a time where the backend takes about 60+% and mysql about 30+% of
>> the cpu)
> Okay, that doesn't look like the BUSQ is involved after all, because
> AFAIK it'd be a long-running query that would instantly show up in the
> processlist. 



> Considering the extreme nature of your recording schedule, you're
> apprently running into some kind of bottleneck, but I have no idea
> which one.

Jens, thanks for looking into this and helping as you did!

Anybody reading this who can explain what and why?

I have three Power Searches running with either
channel.callsign like "NL1"
channel.callsign like "NL2"
channel.callsign like "NL3" in the Search Phrase field.

Every now and then mythbackend starts consuming 60+% and mysql 30+% with
about 50% of the CPU being 'nice'.
This lasts for a few minutes as it appears. Mythweb is getting very slow
in this case.
I tuned mysql using the tuning-primer.sh script.
Noticable thing there:
Current tmp_table_size = 384 M
72% of tmp tables created were disk based
Perhaps you should increase your tmp_table_size

The database files are under 30 megs yet the temp is *more* than 10
times(!!) the database?
The size of the tmp_table appears to grow each time. (!?)

# pwd
# du -sk
24036   .

This is running on a VIA Epia EN12000 with 1GB of RAM and a Terratec
DVB-T card using Fedora 8.
MythTV Version   : exported
MythTV Branch    : trunk
Library API      : 0.22.20080320-2
Network Protocol : 40
QT Version       : 4.3.3
Options compiled in:
 linux release using_oss using_alsa using_backend using_dbox2 using_dvb
using_firewire using_frontend using_hdhomerun using_iptv using_ivtv
using_joystick_menu using_lirc using_opengl_vsync using_v4l using_x11
using_xrandr using_xv using_xvmc using_xvmcw using_xvmc_vld
using_bindings_perl using_bindings_python using_opengl
using_ffmpeg_threads using_libavc_5_3 using_live

Also I filed this ticket http://svn.mythtv.org/trac/ticket/5231 for
mythbackend becoming inresponsive for mythweb after some time.
Dunno if there is a relation.

Anybody can say something about this?

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