[mythtv-users] After 7y5m running, time to start from scratch after update to .27?

Matthias Thyroff lists at thyroff.net
Tue Nov 26 19:44:56 UTC 2013


On 26.11.2013 15:53, R. G. Newbury wrote:
> On 11/25/2013 06:34 PM, Stephen Worthington wrote:
>> On Mon, 25 Nov 2013 21:08:55 +0100, you wrote:
>>
>>> What is not solved is the comunication problem between frontends and 
>>> the
>>> backend (where, sporadically, but then consistently every 10 seconds or
>>> so, I get a huge popup saying "mythcontext: Backend is online" when 
>>> I am
>>> in the recordings screen or also when I watch a recording... see 
>>> archive
>>> for a more detailed description:
>>> http://www.gossamer-threads.com/lists/mythtv/users/555885?search_string=mythcontext;#555885 
>>>
>>> ) That problem went away for about 24 hours after cleaning up my
>>> channels, purging the program table, re-running mythfilldatabase
>>> (thereby reducing the mythconverg database from 2GB to <400MB), and is
>>> back now. I would bet that this problem is not due to the channels 
>>> list.
>>
>> The most likely cause of this problem is communication errors between
>> the frontends and the backend.  When you had 100% CPU, there was a
>> reasonable likelihood that the backend was not responding in time and
>> the frontends were detecting that.  Since the 100% CPU problem seems
>> to be fixed now, I would suggest that you start checking out your
>> ethernet (or is it WiFi) traffic levels.  It is possible for something
>> else other than MythTV to be using too much of the bandwidth and
>> preventing timely access from the frontends to the backend.
>
> Or you have a bad ethernet cable,
> Or the NIC +/- socket in your mythbox is dieing. I am now on the third 
> NIC on my box. The motherboard mounted socket and/or the chipset died. 
> I changed to a USB dongle which was a little flakey ( cheap +/- weird 
> chipset +/- bad module, take your pick) and now have a PCI card setup.
>
> As the ad says, Relief at last.
>
> On another tack, if you suffer from the odd 100% CPU lockup, and you 
> have made changes to your setup wrt backend addresses, then you should 
> check the settings table for duplicate entries or errors. Do:
>
> select * from settings where value like "%IP%":
>
> You should see values for BackendServerIP, BackendServerIP6 and 
> MasterServerIP. Make sure that they are correct. A hostname of 'NULL' 
> is guaranteed to be problematic. And could be the cause of a CPU 
> freeze. (note "could")
>
> Note that an IP of 127.0.0.1 is fine for a combined BE/FE machine, but 
> you cannot use mythweb from outside the box with that setting. You 
> want a 192.168.x.x address (or other defined private address), 
> preferably listed in /etc/hosts with a name, in all your boxen, and 
> set as static served DHCP in your router.
>
> If you then want to charge into that part of the map marked 'Here be 
> Dragons', you can add port forwarding to your router for external 
> access for mythweb, and even VPN, to access and watch your content 
> from whereever you are.
> Damn I love mythtv!
>
> Geoff
>
>
Hello Stephen, Geoff,

thanks for the thought. I have switched now from the PCIe Intel NIC to 
the onboard nic and I have exchanged the cable to the switch. Today, the 
backends were behaving well, so I cannot say that that was the fix, it 
has not gotten worse, either.

What makes me doubt in the hardware/cable/bandwith (GB network, wired) 
theory is that when it fails, it fails on one (maybe two, I think I also 
saw failing two) entries in the recorded programs list. It fails in 
showing the thumbnail and in showing the "recording available" sign in 
the list (i.e. it shows the little grey cross). This one entry fails, 
"mythcontext: backend is online", this item comes back, "mythcontext: 
backend is online", fails... and goes on like that.

My system does not fail on streaming gigabytes of HD content. It never 
fails in showing the programming information or anything else, Only in 
the recorded programs list view, and there, only in one item (random, 
not specific). I also doubt it is access to the recordings directories.

When I start to watch the failing recording, it might take long (5-10 
seconds?) until the recording starts showing, "mythcontext:..." message 
(popping up every few seconds for quite some time, then the messages 
stop.) Once the recording streams, it is not jerky or anything, 
independantly from the message popups.

I once fixed the failing situation by deleting the program description 
from the recorded table in phpMyAdmin. But then, it normaly fixes itself 
at some point, too.

It is something else. Maybe mysql, or it fails on accessing the fanart 
background images which are new (in my setup) since 0.27. (also fails to 
show in the failing situation)

Or the schema. Or a bug. Maybe it is related to the xmltv data in the 
end. Since some time, I get really long descriptions, and sometimes, 
wrong encodings in the myth database (even though the original data 
downloaded by xmltv is correct).

I will keep looking. Thanks again for the support!

Regards,

Matthias



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