[mythtv-users] Frontend locking up and unable to kill it.

[Allen Edwards]

On Wed, Jul 3, 2019 at 9:27 PM Stephen Worthington <stephen_agent at jsw.gen.nz>
wrote:

> On Wed, 3 Jul 2019 17:44:59 -0700, you wrote:
>
> >Twice now the frontend has frozen. If that were not bad enough, I am
> unable
> >to kill it. I have remotely tried to kill it and what I find is a status
> >message on the main screen saying the program has become unresponsive and
> >do I want to shut it down.  But with no visible cursor I cannot click on
> >"Yes" and it does not respond to "Y" from the keyboard. I did a "sudo
> >shutdown now -r" from the remote and the link was immediately cut but the
> >myth computer did not shut down. It is as if mythfrontend was blocking all
> >attempts to close it. I finally held the power button down long enough to
> >turn the computer off and when I restarted it, all was fine. There is just
> >a short section in the frontend log between when my wife started watching
> >her show and the freeze. No log entries after the freeze until the
> restart.
> >
> >Jul  3 07:33:33 NewMyth mythfrontend.real: mythfrontend[1555]: I
> >CoreContext tv_play.cpp:2532 (HandleStateChange) TV::HandleStateChange():
> >Changing from None to WatchingRecording
> >Jul  3 07:33:34 NewMyth mythfrontend.real: mythfrontend[1555]: I
> >CoreContext tv_play.cpp:2638 (HandleStateChange) TV::HandleStateChange():
> >Main UI disabled.
> >Jul  3 07:33:34 NewMyth mythfrontend.real: mythfrontend[1555]: I
> >CoreContext tv_play.cpp:424 (StartTV) TV::StartTV(): Entering main
> playback
> >loop.
> >Jul  3 07:33:34 NewMyth mythfrontend.real: mythfrontend[1555]: N
> >CoreContext mythplayer.cpp:2231 (PrebufferEnoughFrames) Player(f): Waited
> >101ms for video buffers AAAAAAAAAAAAAA
> >Jul  3 07:33:34 NewMyth mythfrontend.real: mythfrontend[1555]: N
> >CoreContext mythplayer.cpp:2231 (PrebufferEnoughFrames) Player(f): Waited
> >203ms for video buffers AAAAAAAAAAAAAA
> >Jul  3 07:33:34 NewMyth mythfrontend.real: mythfrontend[1555]: N
> >CoreContext mythplayer.cpp:2231 (PrebufferEnoughFrames) Player(f): Waited
> >305ms for video buffers LAAAAAAAAAAAAA
> >Jul  3 07:33:34 NewMyth mythfrontend.real: mythfrontend[1555]: I
> >CoreContext mythrender_vdpau.cpp:615 (CheckOutputSurfaces) VDPAU: Added 2
> >output surfaces (total 4, max 4)
> >Jul  3 07:33:34 NewMyth mythfrontend.real: mythfrontend[1555]: N
> >CoreContext mythplayer.cpp:2231 (PrebufferEnoughFrames) Player(f): Waited
> >102ms for video buffers dLAAAAAAAAAAAA
> >Jul  3 07:35:29 NewMyth mythfrontend.real: mythfrontend[1555]: E Decoder
> >mythplayer.cpp:3504 (DecoderGetFrame) Player(f): Decoder timed out waiting
> >for free video buffers.
> >
> >Nothing here that means anything to me that tells me what happened or what
> >to do.
> >
> >Ideally someone can help figure out what is causing the freezes but short
> >of that, how can I shutdown the system?
> >
> > What I tried:
> >sudo kill 1555
> >sudo kill -9 1555
> > sudo killall  mythfrontend.re
> > sudo shutdown now -r
> >
> >Nothing  above would kill the frontend.
> >
> >Allen
>
> That sounds like something else other than mythfrontend was locked up,
> like the kernel.  Check syslog.   When that happens, you can get a
> complete lockup, or it can just make the system very slow, where it
> takes an hour or two to shutdown.  The latter usually happens when one
> or more cores of your CPU are locked up or "stalled" by the software
> running on them.
>
> What distro is it?  If it is Ubuntu, some of the "magic" keys are
> enabled, so that in such a situation, you may be able to get the
> filesystem shut down safely and force a reboot.  Try holding down the
> Alt key, and the SysReq key (PrintScrn if there is no marked SysReq
> key), and then with both those keys down, hit and release all these
> keys in sequence, slowly, with a second or two between keys: REISUB.
>
> See this page for what all those keys do:
>
>
> http://www.ubuntugeek.com/how-to-use-magic-system-request-keys-in-ubuntu-linux.html
>
> Note that the information on that page is for a very old version of
> Ubuntu.  The O key (shutdown) does not work for some reason in modern
> Ubuntus, so you need to use B and have it reboot, and then you can
> shut it down when the BIOS display comes up if that is what you want.
>
> You did manage a remote login - did that take longer than usual to
> work?  Was it slow to respond to commands?
>
> Another option is to enable the systemd debug console:
>
> systemctl enable debug-shell.service
>
> That creates a logged-in root shell on Ctrl-Alt-F9 that comes up early
> in the boot process and does not go away until as late as possible on
> shutdown.  It allows you to use Ctrl-Alt-F9 to see what is preventing
> a shutdown by using "systemctl status" or "systemctl list-units", or
> any other commands.  However, it is a big security hole as it allows
> anyone who knows about it to use Ctrl-Alt-F9 to get root access while
> it is enabled.
>
> And remember that if you did not get the filesystem shut down properly
> before you powered off or rebooted the PC, you must do a full
> filesystem check (fsck -C -f) on all partitions that were mounted at
> the time.  The easiest way to do that is to have a separate small boot
> partition on the PC to do it from, so that you do not have the root
> partition locked.  Or you can use a compatible live DVD or USB stick
> to boot from - one that has the same or better level of filesystem
> drivers.  Keep repeating the fsck -C -f command for each partition
> until there are no more errors reported.
> _______________________________________________
>

Thanks for the reply. I looked at the syslog and other than I am no expert
on what is normal and what is not the best I can tell the system was
running just fine except mythfrontend was locked. When I logged in remotely
it seemed normal. I ran "top" and was able to see normal sort of readouts
which is how I found the PID of mythfrontend. I ran the sudo kill 1555 and
it did nothing.  PID 1555 was still running.  The UI on the local display
(I have two displays, a TV and a LCD display) looked to be working normally
except there was no cursor. But I could more the invisible cursor over to
the menu area and click and get drop downs and such. From syslog it looks
like the system ran a daily cron job after mythfrontend crashed. It seemed
to terminate normally.I can see my remote login in syslog and I can see
when that ended, which was when I did the shutdown.

I find this set of entries odd.  It starts with the stopping of my remote
session (dad) and there is nothing of the same sime sequence above that one
(well there is one).  What is odd is that the time stamp on the second to
last one before the start is out of time sequence.

Jul  3 07:51:36 NewMyth systemd[1]: Stopped Stop ureadahead data collection
45s after completed startup.
Jul  3 07:51:36 NewMyth systemd[1]: Stopping Session c1 of user dad.
Jul  3 07:51:36 NewMyth systemd[1]: Stopping ACPI event daemon...
Jul  3 07:51:36 NewMyth systemd[1]: Stopping RealtimeKit Scheduling Policy
Service...
Jul  3 07:51:36 NewMyth systemd[1]: Stopped target Timers.
Jul  3 07:51:36 NewMyth systemd[1]: Stopped Daily Cleanup of Temporary
Directories.
Jul  3 07:51:36 NewMyth systemd[1]: Stopping Session 596 of user dad.
Jul  3 07:51:36 NewMyth systemd[1]: Stopping Disk Manager...
Jul  3 07:51:36 NewMyth systemd[1]: Stopped target Sound Card.
Jul  3 07:51:36 NewMyth systemd[1]: Stopping User Manager for UID 1000...
Jul  3 07:35:06 NewMyth rsyslogd: message repeated 8 times: [ [origin
software="rsyslogd" swVersion="8.16.0" x-pid="777" x-info="
http://www.rsyslog.com"] rsyslogd was HU
Ped]
Jul  3 07:51:38 NewMyth rsyslogd: [origin software="rsyslogd"
swVersion="8.16.0" x-pid="777" x-info="http://www.rsyslog.com"] exiting on
signal 15.
Jul  3 07:55:21 NewMyth rsyslogd: [origin software="rsyslogd"
swVersion="8.16.0" x-pid="821" x-info="http://www.rsyslog.com"] start

I am running the latest Mythbuntu
Ubuntu 16.04.1 LTS
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mythtv.org/pipermail/mythtv-users/attachments/20190703/4ac55bec/attachment.html>