[mythtv-users] Backend suddenly segfaulting...

[Michael Tiller]

On Sun, May 3, 2009 at 8:54 PM, Michael Tiller <michael.tiller at gmail.com>wrote:

> My frontend turned into a nasty zombie process on Friday night so I
> rebooted my machine.  Now my backend keeps segfaulting.  At first I thought
> perhaps I had a SQL database corruption by I ran a check mysqlcheck on the
> database and everything came up as OK.
>
> I turned on "-v all" and ran the backend in the foreground and sure enough,
> it is segfaulting.  Interestingly, the last line in the log is consistently
> (timestep aside):
>
> 2009-05-03 20:27:25.883 MSqlQuery: SELECT MIN(id),dirname FROM storagegroup
> WHERE hostname = 'mythmc' GROUP BY dirname;
>
> I'm running MythTV out of the Ubuntu repository (8.04) which is
> "mythbackend version: 0.21.20080304-1 www.mythtv.org".
>
> The query is for storagegroup directories and nothing has changed there (no
> directories suddently missing or anything).  Anybody have any ideas?  This
> machine has been running pretty solid for 6-9 months if I recall correctly.
> I don't understand why it should suddently segfault.  Any suggestions?


OK, I've got more data (although not much).  Perhaps this will help.  I ran
the backend under gdb.  The problem is that I'm running the Ubuntu packages
which don't have debugging information.  I'm afraid all I came up with was:

#0  0xb6566019 in QString::QString () from /usr/lib/libqt-mt.so.3
#1  0x08106bec in ?? ()
#2  0x08108078 in ?? ()
#3  0x080d7557 in ?? ()
#4  0x080da1c0 in ?? ()
#5  0x080edced in ?? ()
#6  0x080f181c in ?? ()
#7  0xb5cb74fb in start_thread () from /lib/tls/i686/cmov/libpthread.so.0
#8  0xb5b15e5e in clone () from /lib/tls/i686/cmov/libc.so.6

One other thing I did was to look at the table that appeared to be queried
last (see previous email).  I didn't see any problems with it.  I went so
far as to run mythtv-setup and edit the entries on the off chance that they
got corrupted somehow.  I ran the exact MythTV query through MySql and it
returns two directory names.  Both of them exist so I don't see why any
segfault should result from those.

Of course, just because it is the last thing the backend says before it dies
doesn't mean that it is related.  I suppose something that is not logged
could be causing it.

I couldn't find any Ubuntu packages that included debugging information.  If
anybody knows of any, let me know.

I assume my only resort then is to build the fixes from source (or perhaps
just go whole hog and run trunk if I'm going to bother with building),
correct?

--
Mike
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