[mythtv] Empty and missing recording files when making multiple simultaneous dvb recordings

[Grant Gardner]

On 1 July 2012 06:06, Roger James <roger at beardandsandals.co.uk> wrote:
> On 30/06/12 15:39, Steven Adeff wrote:
>>
>> On Fri, Jun 29, 2012 at 7:17 AM, Roger James
>> <roger at beardandsandals.co.uk> wrote:
>>>
>>> On 28/06/12 21:27, John Pilkington wrote:
>>>>
>>>>
>>>> I posted yesterday about failure to populate the 'watch recordings'
>>>> screen, but I believe this could be another instance of the problem
>>>> above.
>>>>   It looked as if my backend failed when asked to record four dvb-t
>>>> recordings simultaneously.  I hadn't seen this before.  There had been
>>>> lots
>>>> of system changes, and I wondered if the tuner identification had
>>>> failed, so
>>>> I tried running mythtvsetup.  None of the tuners were recognised there,
>>>> although dmesg showed that they had been registered. I have gone back
>>>> from
>>>> kernel 3.4.2-1 to 3.3.7-1 in fedora 16.x86_64 and mythtvsetup sees them
>>>> again.  I didn't make any changes there.  I'm using mythtv 0.24.3 build
>>>> 283
>>>> from ATrpms dated 30 April.  I had made the kernel update earlier this
>>>> week
>>>> when a suitable nvidia module became available at ATrpms.
>>>
>>> John,
>>>
>>> I am only seeing this particular problem since I moved to 0.25. Because
>>> it
>>> is a race condition  is not to say that it did not exist but with a lower
>>> probability in earlier versions. Because the backend ends up with two
>>> threads deadlocked it can produce some strange symptoms in any attached
>>> frontends. I have submitted a bug for it at
>>> http://code.mythtv.org/trac/ticket/10870. The work round is to set any
>>> DVB
>>> cards to only allow one simultaneous recording.
>>
>> is it possible this occurs in similar conditions but not for DVB? I'm
>> having issues with 0.25.1 (after the hdpvr change) that sounds
>> similar, and am wondering perhaps if that change in the hdpvr code is
>> causing a similar condition to occur all the time when two HDPVR are
>> present?
>>
>>
> Yes,
>
> The code is in streamhandler.cpp which is common to all the stream handlers.
> You can see if the bug affects you by turning on "record" logging. I do not
> recommend you run with turned on for long as it can produce very large log
> files. You should then schedule two recordings to start at exactly the same
> time on the same frequency (multiplex in DVB terms, I don't know if HDPVR
> has multiplexes). The error message you are looking for are,
>
> "Programmer Error: Start called before Stop finished" and
>
> "Programmer Error: Stop called before Start finished"
>
> If you are not seeing one or the other of these messages then you are not
> getting the error.
>
> I am currently testing  a patch which you may want to try.

<snip>


Is there a Trac ticket for this?

Pretty sure I'm seeing the same thing "Programmer Error: Start called
before Stop finished" recording 2 programs starting simultaneously on
the same DVB multiplex on a quad core machine running 0.25

Haven't built myth from source for some time but if you need another
tester or more log output etc then let me know.


Grant.