Mailing List Archive: MythTV: Mythtvnz

mythtv-backend-0.25 lockup

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jhaar-ourshack-com at whanau

Jun 19, 2012, 4:59 PM

Post #1 of 7 (577 views)
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mythtv-backend-0.25 lockup

Hi there

Totally weird situation here. Over the weekend I replaced my backend
server with a CentOS-6/x64 system running
mythtv-backend-0.25-286.el6.x86_64, with a USB DVT device. Worked fine -
to begin with. Yesterday I noticed mythweb was no longer working - long
story short - mythbackend is now accepting TCP connections on it's
management ports - but isn't responding.

I went as far as backing up the mysql database and then dropping it and
reinitializing using mythtv-setup. That all worked fine but mythbackend
is still broken. I removed ipv6, the firewall, the USB card, rebooted:
mythbackend logs showed it was happy - but it still didn't respond to
network requests.

So far so normal - here's the kicker. "lsof -ni" shows mythbackend is
LISTEN-ing on all the correct ports, telneting to port 6544 *succeeds*,
"lsof -ni" shows that ESTABLISHed connection - but strace-ing the
mythbackend process *does not show it received the connection*...

It's as if the OS did the three-way TCP handshake and then failed to
pass control to the application??? If I strace xinetd for instance and
then connect to my rsync server, strace sees the incoming connection and
the read/writes that occur - mythbackend does not... The logs do show it
attaching to all the interfaces (ie the logs agree with lsof -ni)

Brand new hardware, RAID1 disks - what the hell!?!? "rpm -V
mythtv-backend" shows the binaries are not corrupt too.

Any ideas - i've run mythbackend with "-v debug" and it shows no issues
- weelllll, the logs do show Bonjour is broken (and it shouldn't - it
was working in the weekend after I figured out to add the 239/8 route) -
but I doubt that's related.

Thanks

Jason

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criggie at criggie

Jun 19, 2012, 8:02 PM

Post #2 of 7 (551 views)
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Re: mythtv-backend-0.25 lockup [In reply to]

Jason Haar wrote:
> Totally weird situation here. Over the weekend I replaced my backend
> server with a CentOS-6/x64 system running
> mythtv-backend-0.25-286.el6.x86_64, with a USB DVT device. Worked fine -
> to begin with. Yesterday I noticed mythweb was no longer working - long
> story short - mythbackend is now accepting TCP connections on it's
> management ports - but isn't responding....

Try disabling selinux straight off, and look for firewall rules with
iptables -L

--
Criggie

http://criggie.org.nz/

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jhaar-ourshack-com at whanau

Jun 19, 2012, 11:52 PM

Post #3 of 7 (547 views)
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Re: mythtv-backend-0.25 lockup [In reply to]

On 20/06/12 15:02, Criggie wrote:
>
> Try disabling selinux straight off, and look for firewall rules with
> iptables -L
>
>

Sorry I forgot to mention that I always disable selinux and I had also
disabled the firewall. In any case, "iptables -L" shows no rules and I'd
have to do some major iptables-foo to match this situation ;-)

Jason

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jhaar-ourshack-com at whanau

Jun 20, 2012, 3:28 AM

Post #4 of 7 (546 views)
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Re: mythtv-backend-0.25 lockup [In reply to]

This is getting weirder.

I threw it through gdb - and it works! But it doesn't work when run
directly? Can a coder tell me why

/usr/bin/mythbackend

doesn't work fully, whereas

gdb /usr/bin/mythbackend
run

...works fine? This is stoopid :-(

Thanks

Jason

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dmoo1790 at ihug

Jun 20, 2012, 5:23 PM

Post #5 of 7 (542 views)
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Re: mythtv-backend-0.25 lockup [In reply to]

On 20/06/12 22:28, Jason Haar wrote:
> This is getting weirder.
>
> I threw it through gdb - and it works! But it doesn't work when run
> directly? Can a coder tell me why
>
> /usr/bin/mythbackend
>
>
> doesn't work fully, whereas
>
> gdb /usr/bin/mythbackend
> run
>
> ...works fine? This is stoopid :-(
>
>
> Thanks
>
> Jason
>

Have you tried running it with the "--user mythtv" argument? Don't know
but seems like it might be a user/permissions problem if gdb runs it but
you can't.

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jhaar-ourshack-com at whanau

Jun 20, 2012, 5:35 PM

Post #6 of 7 (540 views)
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Re: mythtv-backend-0.25 lockup [In reply to]

On 21/06/12 12:23, David Moore wrote:
>
>
> Have you tried running it with the "--user mythtv" argument? Don't know
> but seems like it might be a user/permissions problem if gdb runs it but
> you can't.
>

Yeah - I did do that. All these tests I've been doing as root so it
can't be a permission problem. In fact when I do a strace and
specifically egrep-ped for "denied|such" to see if anything obvious
popped out - not such luck

This is so frustrating. It was all working so well just a few days ago :-(

Jason

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jhaar-ourshack-com at whanau

Jun 25, 2012, 9:25 PM

Post #7 of 7 (501 views)
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Re: mythtv-backend-0.25 lockup [In reply to]

FYI I found the culprit

Found this mythtv ticket

http://code.mythtv.org/trac/ticket/10265

CentOS-6 running dbus - that's what stops mythbackend being able to
respond to incoming TCP requests. I turned it off, restarted mythbackend
and it all worked again

Of course, dbus is pretty important - so now I don't know what killing
it will break. So I've left it on for boot-time, but get mythbackend to
stop it before starting - fingers crossed that'll work out...

Jason

On 21/06/12 12:35, Jason Haar wrote:
> On 21/06/12 12:23, David Moore wrote:
>>
>>
>> Have you tried running it with the "--user mythtv" argument? Don't know
>> but seems like it might be a user/permissions problem if gdb runs it but
>> you can't.
>>
>
> Yeah - I did do that. All these tests I've been doing as root so it
> can't be a permission problem. In fact when I do a strace and
> specifically egrep-ped for "denied|such" to see if anything obvious
> popped out - not such luck
>
> This is so frustrating. It was all working so well just a few days ago :-(
>
> Jason
>
>
> _______________________________________________
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> mythtvnz [at] lists
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