[mythtvnz] Anyone upgraded to V34

[Mark Kendall]

I think I use to have mythtv backend startup dependent on the network 
having started.  From memory the problem I had my script for was that 
after a power cut my server could be up and running before either the 
network router or the HD Homerun and mythtv never looked for the HD 
Homerun again (which I think it may look for now but haven't double 
checked).  I also wanted mythtv running if one/both homeruns weren't 
available, this was all many years ago and homeruns/server are also now 
together on an unmanaged switch instead of the router.

Cheers

On 23/03/2024 12:46 pm, Stephen Worthington wrote:
> On Sat, 23 Mar 2024 10:36:45 +1300, you wrote:
>
>> Discovered that my problem was an old script I had running that looked
>> for HD Homerun units on the network and restarted mythtv-backend when
>> they became available.  Looks like something was going wrong causing
>> lots of backend restarts and consequently restart/start then being
>> blocked.
>>
> >From vague memory of mythtv changes a long time ago I don't think the
>> script is needed anymore so I've disabled it and mythtv 0.34 looks fine
>> now.
> When using networked tuners like HDHomeruns, or using external
> frontends, you do need to use some method of ensuring mythbackend only
> starts after the network is up.  Otherwise there is a race condition
> where mythbackend will only see the localhost network interface and
> will not bring up the normal network interface.  It sounds like you
> have never implemented the right sort of fix for this using systemd,
> and have been relying on your old script doing things externally to
> systemd.  Even though your system now seems to be booting ok, the race
> condition will still exist and at some point the timing of things at
> boot time will change (for example, if you have an ext partition do an
> automatic fsck at boot time).  And then mythbackend will not start
> properly.
>
> The right fix for this when using networked tuners is normally to make
> the mythbackend systemd unit wait until the networked tuners respond
> to network traffic.  With HDHomerun tuners, you can use the
> hdhomerun_config command to tell systemd when the tuners are
> responding.  The best way to do this is to create a new systemd unit
> that calls hdhomerun_config repeatedly until it gets a response.  Then
> have the mythbackend systemd unit wait for the new unit before it
> starts.
>
> Something like this should work (but as I do not have any HDHomerun
> tuners I have not tested this).
>
> sudo systemctl edit wait-for-hdhomerun-response.service
>
> Then paste this into the editor:
>
> [Unit]
> Description=Wait for an HDHomerun networked tuner to respond
> After=network.target
>
> [Service]
> Type=simple
> ExecStartPre=/usr/local/bin/wait-for-hdhomerun-response.sh
> ExecStart=/bin/true
>
> [Install]
> WantedBy=multi-user.target
>
>
> Create the /usr/local/bin/wait-for-hdhomerun-response.sh file and put
> this in it:
>
> #!/bin/bash
>
> TRIES=30
>
> echo "Waiting for HDHomerun"
> for i in $(seq $TRIES); do
>    hdhomerun_config FFFFFFFF get /sys/model > /dev/null 2>&1
>    if [ $? -eq 0 ]; then
>      echo "Found HDHomerun at try $i"
>      exit 0
>    fi
>    sleep 1.0
> done
> echo "Cannot find HDHomerun after $TRIES tries"
> exit 1
>
> Then do:
>
> sudo chown root:root /usr/local/bin/wait-for-hdhomerun-response.sh
> sudo chmod a=r,g=r,u=rwx /usr/local/bin/wait-for-hdhomerun-response.sh
>
> sudo systemctl edit mythtv-backend.service
>
> Paste this into the editor:
>
> [Unit]
>
> Wants=wait-for-hdhomerun-response.service
> After=wait-for-hdhomerun-response.service
>
>
> Then do:
>
> sudo systemctl daemon-reload
>
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