[mythtv-users] CTRL-ALT-BACKSPACE -> multiple instances of mythfrontend

[Allen Edwards]

On Sun, Mar 10, 2019 at 9:50 AM Allen Edwards <allen.p.edwards at gmail.com>
wrote:

> Hi Ian and Stephen,
>
> You guys were busy as I slept so I am creating a single response.
>
> As to what I am running this is what I know
>
> *dad at NewMyth:~$ lsb_release -a*
> *No LSB modules are available.*
> *Distributor ID: Ubuntu*
> *Description:    Ubuntu 16.04.1 LTS*
> *Release:        16.04*
> *Codename:       xenial*
>
>
> *dad at NewMyth:~$ apt-cache policy mythtv*
> *mythtv:*
> *  Installed: 2:0.28.2+fixes.20180827.9031599-0ubuntu0mythbuntu2*
> *  Candidate: 2:0.28.2+fixes.20180827.9031599-0ubuntu0mythbuntu2*
> *  Version table:*
> * *** 2:0.28.2+fixes.20180827.9031599-0ubuntu0mythbuntu2 500*
> *        500 http://ppa.launchpad.net/mythbuntu/0.28/ubuntu
> <http://ppa.launchpad.net/mythbuntu/0.28/ubuntu> xenial/main i386 Packages*
> *        100 /var/lib/dpkg/status*
> *     2:0.28.0+fixes.20160413.15cf421-0ubuntu2 500*
> *        500 http://us.archive.ubuntu.com/ubuntu
> <http://us.archive.ubuntu.com/ubuntu> xenial/multiverse i386 Packages*
>
>
> And to Ian's question:
>
> *dad at NewMyth:~$ ls -la /home/dad/.config/autostart*
> *total 16*
> *drwxrwxr-x  2 dad dad 4096 Oct 14 09:22 .*
> *drwxrwxr-x 12 dad dad 4096 Feb 24 17:14 ..*
> *lrwxrwxrwx  1 dad dad   38 Aug 25  2018 mythtv.desktop ->
> /usr/share/applications/mythtv.desktop*
> *-rw-rw-r--  1 dad dad   30 Oct 14 09:19 pulseaudio.desktop*
> *-rw-rw-r--  1 dad dad   29 Oct 14 09:22 xfsettingsd.desktop*
>
>
> I must say, I did think your solution of killing mythfrontend via the
> remote to be a good and elegant one.  Given that a remote is nearly always
> to hand, it's about as user-friendly as it could be.  So far, we have gone
> down this rabbit hole a bit - the question now is whether to go further
> down it or give up...
>
> For a number of reasons having to do with what we are used to, the
> difficulty of programming and using the remote, and the unknowns of
> changing the lirc code, I prefer to continue on the CTRL-ALT-BS question as
> I think we are very close to a solution with all the thought you two have
> put into this. It could also be of benefit to others if a good solution is
> found.
>
> ultimately suggest running mythfrontend without the --service option
>
> If Myth is being run by that script from 2007 that doesn't even run
> correctly I must ask does myth still crash often enough that the auto
> restart is necessary?  This seems like a super easy solution unless the
> underlying program crashes constantly. BTW, I tested it and it works.
>
> Of course, I may not know if this script is restarting myth but I doubt it
> as we can see that it does't work.  The crashes I get of myth are freeze
> up.  Still possible I would not know but worth thought as if the script
> really is 12 years old then perhaps it is solving a problem that is no
> longer a problem.
>
> Clicking on the Edit button reveals that this runs:
> *  mythfrontend --service*
>
> Correct. What is your opinion on how important the --service is at this
> point? That script is really old if the comments are correct.
>
> If the --service option is necessary am I correct that the suggestion is
> to change this line
>
> *pidof mythfrontend.real 2>&1 >/dev/null && wmctrl -a "MythTV Frontend"
> 2>/dev/null && exit 0*
>
> To this
>
> *pidof mythfrontend.real 2>&1 >/dev/null*
> *pidof_retcode=$?*
> *if [ $pidof_retcode==0 ]; then*
> *  wmctrl -a "MythTV Frontend" 2>/dev/null*
> *  wmctrl_retcode=$?*
> *else*
> *  wmctrl_retcode=1*
> *fi*
> *if [ pidof_retcode==0 || wmctrl_retcode==0 ]; then*
> *  exit 0*
> *fi*
>
> By the way, *pidof mythfrontend.real *returns 3524 (the pid) and *wmctrl
> -a "MythTV Frontend"  *doesn't return anything at least on a terminal but
> I think that is normal.
>
> What I think is going on is that X closes mythfrontend.real but does not
> close the service.  Then when X opens again and checks if myth is running
> the service has not had time to get its version of myth running so the pid
> returns null or 0. This happens so fast and all the services start versions
> of myth before the pid is valid. One key is that when I do CTRL-ALT-BS I
> don't always get a new instance, just 80-90% of the time.  This says to me
> there is a timing component to the problem.  My computer is much faster
> with the new RAM and my guess is that mostly all the services are busy
> starting an instance of myth before a pid is established. Perhaps what is
> needed as the first line of the script is a delay.
>
> I will test the proposed script changes when I hear from you that I
> understand it correctly and continue to think it is a good idea. Until
> then, I am running mythfrontend without the service option. My gut says
> that is the best solution anyway.   That script is just too old. I don't
> trust it and doubt that it is necessary any longer.
>
> Allen
>
>
As I said, eliminating the --service from the autostart edit solved the
problem. I have now tried some edits on the script.

Adding delay to  /usr/share/mythtv/mythfrontend.sh makes it so I only get
two instances of mythfrontend instead of one more for every restart. That
says to me there are two mechanisms and adding the delay cured one of them.
Recall that previously when I did ten restarts I had nine instances of
mythfrontend running. I thought this was interesting data so wanted to
share it.  It might help in figuring out what is going on as we descend
further down the rabbit hole.

Changing the first line to the suggestion in bold above and keeping the
delay (sleep 1) in was the same as keeping the old code.  I would get 2
instances of mythfrontend regardless of how many times I did a reset.  That
does not surprise me as the way I read it, it does the same thing as the
single line.  The single line relies on the property that the expression is
evaluated from left to right and only does the next test if the first one
passes.  It is very clever but also very hard to read.  The suggested edit
is easier to read but I think does the same thing.

I have reverted back to not running mythfrontend as a service. I continue
to feel this is the best solution.  That script is old and is basically a
hack to solve a problem that I would hope is no longer there. But I will
find out since I am running without it as a service.

There are two possible paths now.  One is to do nothing and see if myth
crashes and needed the autostart. The other is to continue down the rabbit
hole and try and solve the problem with the script.  My preference is to
continue the search for a solution to the script's issues but I do not feel
strongly one way or the other.

Allen
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