Entering Watch Recordings slower than expected in v32

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link
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Entering Watch Recordings slower than expected in v32

Post by link »

After updating both frontends and backend to MythTV 32, I've noticed that it takes noticeably longer for the Watch Recordings menu to come up than in v31. I don't have significantly more recordings than before the upgrade, and I don't see anything in either frontend or backend logs when I pull up the menu that would help explain the cause. Any suggestions?

I'm using MythCenter-Wide 1.10 as my theme, if that is relevant.
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Re: Entering Watch Recordings slower than expected in v32

Post by white_haired_uncle »

I recently moved from 31 to 32 (and then 33), and MythCenter-Wide 1.9 to 1.10. I haven't noticed any difference in waiting for Watch Recordings to load. The GUI "fade" as I move between menus drove me nuts at first, but I'm getting used to it.

FWIW, part of the upgrade involved moving the backend/DB to a VM (same physical host) which lowered the CPU/RAM considerably. Also swiched to mariaDB. I run pretty ancient hardware (AMD Phenom), and with about 5,000 recordings it takes about five seconds to load Watch Recordings.

I know that's not any real help to you, but maybe it'll add a little context from a similar configuration.
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paulh
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Re: Entering Watch Recordings slower than expected in v32

Post by paulh »

Do you have a lot of recordings?

There was a new feature added to show a watched progress that could possibly slowdown loading and rendering of the program list. Do you see it with other themes that don't show the watched progress bars? I wouldn't have thought it would have made a big impact but if you have 1000's of recordings it only takes a tiny fraction of a second longer per recording to add up to a big delay with 1000's of recordings.
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Re: Entering Watch Recordings slower than expected in v32

Post by link »

I have ~2250 recordings, I'm haven't had a chance to try a different theme yet, but I'm guessing this is the culprit.
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Re: Entering Watch Recordings slower than expected in v32

Post by white_haired_uncle »

link wrote:
Sun Mar 12, 2023 9:44 pm
After updating both frontends and backend to MythTV 32,
Did you happen to do any OS updates around the time?

I did one this weekend, just the latest updates to Ubuntu 22.04LTS, and now entering watch recordings takes several minutes, and once I'm in about 15-20 seconds to respond to each keystroke.

Fortunately, my frontend is diskless and I like to back it up before making changes, so I can boot into either the before/good or after/broke environment
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Re: Entering Watch Recordings slower than expected in v32

Post by paulh »

@ white_haired_uncle Do the logs give any indication why it is so slow?
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Re: Entering Watch Recordings slower than expected in v32

Post by white_haired_uncle »

EDIT: For me, the problem appears to be kernel 5.15.0-67. I can take a working system (5.15.0-60), do nothing more than

Code: Select all

# apt install  linux-generic linux-headers-generic
reboot, and it's broke. I should mention, I'm pretty sure it's not just mythtv, icewm takes a long time (though not as bad) to get going as well. Reboot back into 5.15.0-60, and all is well again.
/EDIT

paulh wrote:
Mon Mar 20, 2023 5:57 pm
@ white_haired_uncle Do the logs give any indication why it is so slow?
Nothing that means anything to me. By default, the frontend log shows nothing. With -v all --loglevel debug it shows way too much, but nothing stands out. Tried to gzip and attach, but once I got under the size limit I get the "board attachment quota" error.

Once Watch Recordings finally comes up, when I move into All Programs, it takes about 20 seconds to move up/down from one recording in the menu to the next (there are about 5500).

If I stay in the left hand menu (mythcenter-wide), it takes about 20 seconds to up/down from one title to the next. There are about 100 titles.

If I enter the subtitles menu for a specific title, the first one takes 15-20 seconds to become active, and then the performance of moving up or down between subtitles is related to the number of subtitles for said title. Not linear, but certainly noticeable. For 2 subtitles, it's over a second (which is still very slow). With 10 subtitles, 2-3 seconds. Around 100, 3-4 seconds. Around 300, 5+ seconds.

As far as I can see, there is no previewgen happening. I've also moved back and forth to be sure.

No network errors visible.

mysql> select * from recorded; # runs in a tiny fraction of a second

Never was any good at looking at NFS performance (/ is on NFS, and hopefully the frontend is using it to access recordings). Reads and writes of >100MB show no performance issue.
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paulh
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Re: Entering Watch Recordings slower than expected in v32

Post by paulh »

Looks like this bug which affects NFS performanace
https://bugs.launchpad.net/ubuntu/+sour ... ug/2009325
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Re: Entering Watch Recordings slower than expected in v32

Post by white_haired_uncle »

Updated to linux kernel 5.15.0-17. Seems to have fixed the NFS issue.
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