Mailing List Archive

On 10/11/2010 08:09 AM, James Crow wrote:
> I have been running Mythbuntu 10.04 w/ 0.24 autbuilds for a few weeks.
> A couple of times a week my MBE locks up. It does not segfault, it
> just stops responding to any FE and the current recordings on the MBE
> stop as well. The problem always occurs just as a show is starting to
> record. I want to make sure I get the required debugging data to
> submit a ticket.
>
> I have the mythtv-dbg build installed. I think I will need to run
> mythbackend under gdb as per the documentation. On Mythbuntu the BE is
> normally run as user mythtv. Should I alter the upstart script to make
> mythbackend run under gdb? Should I start gdb/mythbackend from a
> normal shell and wait for the lockup to Ctrl-C the gdb process? I
> think the documentation is describing a situation where the BE seg
> faults rather than just locks up. Any ideas of the proper way to
> generate a backtrace under these circumstances is appreciated.

Another option is to run mythbackend normally, then attach gdb to the
running (and locked up) process, as at

http://sourceware.org/gdb/download/onlinedocs/gdb/Attach.html#Attach

Find the process ID for the appropriate mythbackend process (remember
that in 0.23-fixes and below, some mythbackend processes are used to
generate previews, so you will likely want to use the oldest of the
processes).

ps -efw | grep mythback

Once you know the process ID, start gdb and submit the commands:

handle SIGPIPE nostop noprint
handle SIG33 nostop noprint
set logging on
set pagination off
set breakpoint pending on
break qFatal
thread apply all bt full

and once you've gotten the information you need,

set logging off

Once you've been through the process, free to clean up the instructions
(and fix any incorrect info I put in) and add a new section 4 to:
http://www.mythtv.org/wiki/Debugging

Thanks,
Mike

(Yeah, some of those commands aren't necessary, but they won't hurt and
I figured it's better to make generic instructions that would allow
anyone to use this approach--even if their backend isn't locked up or
whatever, and they planned to continue running under gdb.)
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On Mon, Oct 11, 2010 at 12:53 PM, Michael T. Dean
<mtdean@thirdcontact.com> wrote:
>  On 10/11/2010 08:09 AM, James Crow wrote:
>>
>> I have been running Mythbuntu 10.04 w/ 0.24 autbuilds for a few weeks.
>> A couple of times a week my MBE locks up. It does not segfault, it
>> just stops responding to any FE and the current recordings on the MBE
>> stop as well. The problem always occurs just as a show is starting to
>> record. I want to make sure I get the required debugging data to
>> submit a ticket.
>>
>> I have the mythtv-dbg build installed. I think I will need to run
>> mythbackend under gdb as per the documentation. On Mythbuntu the BE is
>> normally run as user mythtv. Should I alter the upstart script to make
>> mythbackend run under gdb? Should I start gdb/mythbackend from a
>> normal shell and wait for the lockup to Ctrl-C the gdb process? I
>> think the documentation is describing a situation where the BE seg
>> faults rather than just locks up. Any ideas of the proper way to
>> generate a backtrace under these circumstances is appreciated.
>
> Another option is to run mythbackend normally, then attach gdb to the
> running (and locked up) process, as at
>
> http://sourceware.org/gdb/download/onlinedocs/gdb/Attach.html#Attach
>
> Find the process ID for the appropriate mythbackend process (remember that
> in 0.23-fixes and below, some mythbackend processes are used to generate
> previews, so you will likely want to use the oldest of the processes).
>
> ps -efw | grep mythback
>
> Once you know the process ID, start gdb and submit the commands:
>
> handle SIGPIPE nostop noprint
> handle SIG33 nostop noprint
> set logging on
> set pagination off
> set breakpoint pending on
> break qFatal
> thread apply all bt full
>
> and once you've gotten the information you need,
>
> set logging off
>
> Once you've been through the process, free to clean up the instructions (and
> fix any incorrect info I put in) and add a new section 4 to:
>  http://www.mythtv.org/wiki/Debugging
>
> Thanks,
> Mike
>
> (Yeah, some of those commands aren't necessary, but they won't hurt and I
> figured it's better to make generic instructions that would allow anyone to
> use this approach--even if their backend isn't locked up or whatever, and
> they planned to continue running under gdb.)

Excellent. Now all I have to do is what for mythbackend to lockup
again. :) The only catch is it normally happens at 8PM just as the
primetime shows start to record. Maybe I should setup some throwaway
recordings so that all recorders start simultaneously to test.

Thanks,
James
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On Mon, Oct 11, 2010 at 3:17 PM, James Crow <crow.jamesm@gmail.com> wrote:
> On Mon, Oct 11, 2010 at 12:53 PM, Michael T. Dean
> <mtdean@thirdcontact.com> wrote:
>>  On 10/11/2010 08:09 AM, James Crow wrote:
<snip>
>>
>> Another option is to run mythbackend normally, then attach gdb to the
>> running (and locked up) process, as at
>>
>> http://sourceware.org/gdb/download/onlinedocs/gdb/Attach.html#Attach
>>
>> Find the process ID for the appropriate mythbackend process (remember that
>> in 0.23-fixes and below, some mythbackend processes are used to generate
>> previews, so you will likely want to use the oldest of the processes).
>>
>> ps -efw | grep mythback
>>
>> Once you know the process ID, start gdb and submit the commands:
>>
>> handle SIGPIPE nostop noprint
>> handle SIG33 nostop noprint
>> set logging on
>> set pagination off
>> set breakpoint pending on
>> break qFatal
>> thread apply all bt full
>>
>> and once you've gotten the information you need,
>>
>> set logging off
>>
>> Once you've been through the process, free to clean up the instructions (and
>> fix any incorrect info I put in) and add a new section 4 to:
>>  http://www.mythtv.org/wiki/Debugging
>>
>> Thanks,
>> Mike
>>

My MBE locked up again last night. I was sitting at my desktop when I
noticed and I was able to generate a gdb backtrace. The gdb.txt file
is ~129k. Should I just open a new ticket with the gdb log and the
mythbackend.log file or do I need to trim some of the data from the
gdb.txt log?

Thanks,
James
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On Wed, Oct 13, 2010 at 5:51 AM, James Crow <crow.jamesm@gmail.com> wrote:
>
> My MBE locked up again last night. I was sitting at my desktop when I
> noticed and I was able to generate a gdb backtrace. The gdb.txt file
> is ~129k. Should I just open a new ticket with the gdb log and the
> mythbackend.log file or do I need to trim some of the data from the
> gdb.txt log?
>
> Thanks,
> James

It sounds like (since you mention a SBE in the other thread) you are
experiencing this:

http://svn.mythtv.org/trac/ticket/8526

In which case feel free to apply the patch to all your systems and test.

Robert
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On Wed, Oct 13, 2010 at 6:37 AM, Robert McNamara
<robert.mcnamara@gmail.com> wrote:
> On Wed, Oct 13, 2010 at 5:51 AM, James Crow <crow.jamesm@gmail.com> wrote:
>>
>> My MBE locked up again last night. I was sitting at my desktop when I
>> noticed and I was able to generate a gdb backtrace. The gdb.txt file
>> is ~129k. Should I just open a new ticket with the gdb log and the
>> mythbackend.log file or do I need to trim some of the data from the
>> gdb.txt log?
>>
>> Thanks,
>> James
>
> It sounds like (since you mention a SBE in the other thread) you are
> experiencing this:
>
> http://svn.mythtv.org/trac/ticket/8526
>
> In which case feel free to apply the patch to all your systems and test.
>
> Robert
>

And sorry, to clarify, there are two patches, you'd want to apply both
to all systems.
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On Wed, Oct 13, 2010 at 9:48 AM, Robert McNamara
<robert.mcnamara@gmail.com> wrote:
> On Wed, Oct 13, 2010 at 6:37 AM, Robert McNamara
> <robert.mcnamara@gmail.com> wrote:
<snip>
>>
>> It sounds like (since you mention a SBE in the other thread) you are
>> experiencing this:
>>
>> http://svn.mythtv.org/trac/ticket/8526
>>
>> In which case feel free to apply the patch to all your systems and test.
>>
>> Robert
>>
>
> And sorry, to clarify, there are two patches, you'd want to apply both
> to all systems.

I had seen those patches and tried to apply them while running 0.23.1
w/o success. I just tried to apply the patches to the newest mythbuntu
auto-build (26766) and they apply cleanly. However I am having
problems with dependencies that are not met while trying to build the
package. There is a mythbuntu bug (586007) that should be fixed in the
version I have but it is not working. Something to do with
libqtwebkit-dev and upstream Debian package name changes. Once I find
a fix for this problem I will try the patches from 8526.

Thanks,
James
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On Wed, Oct 13, 2010 at 10:59 AM, James Crow <crow.jamesm@gmail.com> wrote:
>
> I had seen those patches and tried to apply them while running 0.23.1
> w/o success. I just tried to apply the patches to the newest mythbuntu
> auto-build (26766) and they apply cleanly. However I am having
> problems with dependencies that are not met while trying to build the
> package. There is a mythbuntu bug (586007) that should be fixed in the
> version I have but it is not working. Something to do with
> libqtwebkit-dev and upstream Debian package name changes. Once I find
> a fix for this problem I will try the patches from 8526.
>
> Thanks,
> James
>

I got my problems compiling a new Mythbuntu package straightened out
and now I have a build that includes the patches from ticket 8526.

Thanks,
James
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