[mythtv-users] mythbackend not responding - and even more weirdness

Darren fender_bender at aandr.com.au
Sun Dec 17 04:25:52 UTC 2006


Most likely network or somehow the ports a getting blocked. You can check for 
open or listening ports using netstat -lp |grep myth as root, route -n will 
show the routing table more important is the gateway if there is one. If 
network settings are ok then check the system logs 

goodluck
Darren

> Hello everyone. I just joined the list and I apologize for such a long
> first post, but I am seeing such a strange set of issues so I will try
> to include as much info right up front. Please bear with me. :)
>
>
> Lemme try to explain:
>
> Everything works fine for a while, then randomly the mythbackend stops
> responding to the frontend (and the Mythweb interface). But, mythbackend
> is not 'hung'. It continues to query the MySQL database, and continues
> to log to its own mythbackend.log. (nothing interesting jumps out at me
> in that log though)
>
> The frontend will timeout and complain that the backend is gone, and of
> course the "Watch Recordings" page and "Scheduled recordings" pages are
> blank.
>
> But... here is the strange part: If I run strace without the -f (follow
> child processes) I get this:
>
> # strace -s0 -p 26534
> Process 26534 attached - interrupt to quit
> futex(0x654618, FUTEX_WAIT, 2, NULL
>
> And it just sits there... and nothing changes in the frontend (which is
> running in a window for easy monitoring).
>
> BUT if I run that same strace with the -f parameter, all of a sudden the
> mythfrontend comes alive and is able to communicate with the backend and
> the "Watch recordings" page is automatically populated and I can choose
> a recording to watch and it works fine.
>
> When the strace -f process is killed, the mythfrontend again can no
> longer communicate with the backend... Restart the strace -f and the
> mythfrontend comes back to life and works perfectly again.
>
> Meanwhile, whenever the backend is not responding to the frontend, no
> scheduled recordings take place, and the mythfrontend logs:
>
> 2006-12-16 13:48:24.328 Connecting to backend server: 192.168.254.4:6543
> (try 1 of 5)
> 2006-12-16 13:48:31.332 MythSocket(2aaab1cf1f50:34): readStringList:
> Error, timeout (quick).
> 2006-12-16 13:48:31.332 Unexpected response to MYTH_PROTO_VERSION:
> 2006-12-16 13:48:31.332 ProgramList::FromScheduler(): Error querying
> master.
>
>
> I know. This is very strange. I was just running strace to see what
> mythbackend was trying to do when it was not responding to the frontend.
> No idea why or how strace could affect how the backend process acts.
>
> Here are the system details:
>
> - Gentoo Linux
> - AMD Athlon64 X2
> - 2GB RAM
> - # free
>              total       used       free
> Mem:       2059492    2035936      23556
> -/+ buffers/cache:    1384692     674800
> Swap:      1028000     436108     591892
>
> - Hauppauge Wintv-PVR500 dual tuner card
> - ivtv version 0.8.1 (tagged release) loading
> - Kernel Linux version: 2.6.18 SMP preempt mod_unload gcc-3.4
> (I just noticed the preempt above. I thought I read somewhere NOT to use
> that kernel option with MythTV... Could that be it?)
>
> - /mnt/store is an NFS mount with the following mount options:
> remote_server:/mnt/store on /mnt/store type nfs
> (rw,rsize=8192,wsize=8192,hard,intr,nfsvers=3,actimeo=0,addr=192.168.254.3)
>
> - Filesystem on remote server is jfs
> - MySQL database is v4.1.22
> - mythbackend --version reports:
> Library API version: 0.20.20060828-3
> Source code version: exported
> Options compiled in:
>  linux release using_lmsensors using_v4l using_oss using_alsa using_ivtv
> using_firewire using_x11 using_xv using_xrandr using_opengl_vsync
> using_opengl using_frontend using_backend using_bindings_perl
>
> - $ mythfrontend --version reports:
> 2006-12-16 13:40:20.588 Using runtime prefix = /usr
> 2006-12-16 13:40:20.597 DPMS is disabled.
> 2006-12-16 13:40:20.629 New DB connection, total: 1
> 2006-12-16 13:40:20.637 Connected to database 'mythconverg' at host:
> localhost
> 2006-12-16 13:40:20.639 Total desktop dim: 1680x1050, with 1 screen[s].
> 2006-12-16 13:40:20.644 Using screen 0, 1680x1050 at 0,0
> Library API version: 0.20.20060828-3
> Source code version: exported
> Options compiled in:
>  linux release using_lmsensors using_v4l using_oss using_alsa using_ivtv
> using_firewire using_x11 using_xv using_xrandr using_opengl_vsync
> using_opengl using_frontend using_backend using_bindings_perl
>
> Neither processor ever has more than a 20% utilization - both fluctuate
> anywhere between 0 and 20 and this is with other apps opened and
> running. Also system load sits around 0.6 so there are no system loading
> issues. :-/
>
>
> ANY and ALL thoughts are appreciated. I would be willing to provide any
> additional information to help resolve this issue.
>
> BTW, from what I have seen so far MythTV is pretty awesome. Nice job
> devs!  :)
>
> --
> Bill Arlofski
> Reverse Polarity
> waa-mythtv at revpol.com
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>
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