virtuoso-t constantly segfaulting

[Thomas Tanghus]

On Sunday 26 January 2014 23:33 Duncan wrote:
> Kevin Krammer posted on Sun, 26 Jan 2014 23:48:02 +0100 as excerpted:
> > On Sunday, 2014-01-26, 23:42:12, Thomas Tanghus wrote:
> >> The past week or so I get this every 10-20 seconds in/var/log/syslog:
> >> 
> >> kernel: [168098.800123] virtuoso-t[13981]: segfault at ffffffff ip
> >> 0851efbb sp a7143870 error 7 in virtuoso-t[8048000+aa0000]
> >> 
> >> I get several hits when searching for it, but no solution to how to fix
> >> it, and it makes the log almost unusable.
> >> 
> >> Any idea what is going on?
> >> 
> >> I run KDE Platform 4.12 on Kubuntu 13.10.
> > 
> > Since this is Kubuntu it could be AppArmor interfering, e.g. not
> > allowing virtuoso to access its files or something.
> 
> Good point.
> 
> > It is kind of strange though that a user process would log to syslog.
> 
> Note that it's actually the kernel doing the logging to syslog, logging
> the segfault of the app in question!
> 
> Barring a simple fix for virtoso, my solution to the syslog noise problem
> would be a syslog filter to filter out that noise.  I've done that a
> number of times here.

(K)Ubuntu uses rsyslog and I did once kinda manage to filter out specific 
notifications by app name (I use syslog for ownCloud testing), but I forgot to 
write down what I did, and my changes got lost in an update...

But I'd rather find out what's wrong than hide the issue, and since I'm 
usually a happy user of both Akonadi and Nepomuk - in so much that they have 
just done their job without giving me any problems - so purging them is not an 
option.

--snip--snip--snip--

> That said, the possibility that immediately comes to mind here is that
> its database is corrupted perhaps by an unclean shutdown aka system crash
> just as virtuoso was writing something, so that now, when it (apparently
> repeatedly) tries to load, it hits that corrupt database and segfaults.

That does sound very likely, and as I wrote I did have a power outage not long 
ago. I managed to save Akonadi with a backup, but my backup routine is a 
simple rsync once a week, and that week has sadly long passed.

> If that's correct, the fix should in theory be pretty simple: Find that
> database and delete it, allowing nepomuk/virtuoso to rebuild it as
> necessary (or turning it off at runtime at least, if you don't use it, so
> it doesn't rebuild the database).
> 
> The problem is finding and deleting that database.  Since I'm not running
> it here and long ago deleted it, I can't tell you for sure where to
> look.  Perhaps Kevin can help with that.

Yes, I'd rather not go and wipe everything - or even worse some of it, leading 
to even more data corruption, so I'm hoping someone with their hands deeper in 
can guide me there.

> ---
> [1] Short:  Caveat, just so readers know and as I'm sure Kevin can
> attest, my "short" could well end up being several hundred lines of
> example and instructions! =:^)

If you search through your emails (1-2 years?) you will find one from me 
urging you to keep your otherwise excellent explanations a tad shorter, and I 
must say your mails have gotten a lot more comprehensible, since apparently I 
was not alone on the request :)
I admire your willingness to help people on this and other lists, and also to 
respond thoughtfully to constructive criticism.

-- 
Med venlig hilsen / Best Regards

Thomas Tanghus
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