[mythtv-users] MythFrontend out of memory problem

Kenneth Emerson kenneth.emerson at gmail.com
Mon Apr 11 18:04:13 UTC 2022


On Mon, Apr 11, 2022, 12:53 AM Stephen Worthington <stephen_agent at jsw.gen.nz>
wrote:

> On Sun, 10 Apr 2022 23:00:17 -0500, you wrote:
>
>
> >> Stephen:
> >
> >
> >
> >The system RAM is 8Gb.  There is a 2Gb swap space.  There are about 3,000
> >recordings.  Here is the output from swap.sh:
> >
> >
> >ken at mythtv:~$ ./swap.sh
> >
> >
> >..............................
> >
> >Overall swap used: 798096 kB
> >
> >
> >========================================
> >
> >kB      pid     name
> >
> >
> >========================================
> >
> >404072  1408    mythfrontend.re
> >
> >77376   1365    xfdesktop
> >
> >42080   1277    xfwm4
> >
> >38504   1377    applet.py
> >
> >37120   1509    blueman-tray
> >
> >34504   1426    blueman-applet
> >
> >15624   1131    xfce4-session
> >
> >14224   1310    panel-1-whisker
> >
> >12480   1321    panel-10-pulsea
> >
> >12224   1317    panel-8-statusn
> >
> >11536   1314    panel-6-notific
> >
> >10552   1401    update-notifier
> >
> >10216   1411    nm-applet
> >
> >9408    1360    Thunar
> >
> >9336    1282    xfsettingsd
> >
> >8608    1313    panel-5-systray
> >
> >8576    1318    panel-9-power-m
> >
> >8528    1385    xfce4-power-man
> >
> >8240    1315    panel-7-indicat
> >
> >5840    1283    xfce4-panel
> >
> >3280    12076   bash
> >
> >3272    1382    xiccd
> >
> >3032    3791    bash
> >
> >2688    1123    systemd
> >
> >2640    1442    polkit-gnome-au
> >
> >1920    1130    pulseaudio
> >
> >1224    1437    agent
> >
> >504     1145    dbus-daemon
> >
> >248     3784    tmux: server
> >
> >240     1368    mythfrontend
> >
> >
> >ken at mythtv:~$ free -m
> >
> >
> >                    total        used        free      shared  buff/cache
> >available
> >Mem:           7934        2964         202           7        4768
> > 4668
> >
> >If it's meaningful the CPU is an Intel i5-2500K 3.3GHz
> >
> >Perhaps I am hitting some limit on number of recordings, but I don't ever
> >remember there being a (soft?) limit.
> >The system is a bit old, but I would hope it's powerful enough.  I only
> use
> >it as a media center with only MythTv as the main application.
> >
> >Regards,
> >
> >Ken Emerson
>
> With 8 Gibytes of RAM, it should be fine.  Only 3000 recordings is not
> a problem (I have 52880 on an 8 Gibyte frontend/backend system). There
> is no fixed limit on recordings - the list can grow as big as your
> system will allow, although things do slow down a bit when you have as
> many as I do.
>
> It does look like the swap space is filling up though - I would
> suggest increasing that to 8 Gibytes.  But it is currently using
> 798096 kiB, which is under half full so it is not obvious that it will
> run out of swap.
>
> I have my system and swap partitions on a fast M.2 NVME SSD, which
> helps with swapping.
>
> The free command gives you the total RAM and swap usage.  This is my
> system with mythfrontend showing my recordings list:
>
> root at mypvr:~# free -m
>               total        used        free      shared  buff/cache
> available
> Mem:           7902        2829         120          23        4952
> 4752
> Swap:         10239        1556        8683
>
> (Sorry about the line wrapping - my email client does that and it is
> not able to be turned off).
>
> So your frontend only system with only 3000 recordings should be just
> fine.  So my best guess is that something is triggering a bug that is
> causing a memory leak.  But the problem might be in another program,
> rather than mythfrontend.  The OOM system is known for killing the
> largest RAM user, when the problem program that is suddenly using up
> RAM is a different program.
>
> There was one old bug that caused the cache directory not to be
> cleaned up properly, and mythfrontend would then load the cache and
> run out of RAM.  That was fixed a while ago, but it is possible that
> you still somehow have a huge cache.  So take a look at
> $(HOME)/.mythtv/cache and see how big it is:
>
> root at mypvr:~# du -hcs /home/stephen/.mythtv/cache/
> 376M    /home/stephen/.mythtv/cache/
> 376M    total
>
> This mine now, but when the bug was happening, it was many gibytes. If
> yours is too large, shut down mythfrontend and do:
>
> rm -r $(HOME)/.mythtv/cache
>
> Mythfrontend should then rebuild the cache as required.
>
> I would suggest upgrading to v32.  That is the currently supported
> version, so if you have a problem that needs the devs to fix it, you
> will need to be on v32 for them to be interested.  And it is vaguely
> possible your problem may be fixed already in v32-fixes.
>
>
> Stephen:

Unfortunately, I decided to take the plunge and upgrade to 32. Looked
simple; however, in stuck years ago right at the beginning running
mythtv-setup with "Failed to get schema upgrade lock". Can't go back or
forward at this point. I have a good DB backup just don't know what to do
with it.

Ken Emerson
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