[mythtv-users] Moving through

Ryan Duffy dusteur at excite.com
Sat Feb 17 12:25:58 UTC 2007

 Jonathan Rogers wrote:
> On Thu, 2006-12-14 at 09:26 -0500, Ryan Duffy wrote:
>>> this is slow all the time, its like 2.5 to 3.0 seconds each time I
>>> move up and down.
>> Mine is slow (about 2-3 seconds) but only after watching a recording then exiting back to the recordings list. If I back out one more menu level, and move back into the recordings list, it is very quick to move between recordings again.
> I have almost exactly the same problem that Ryan Duffy describes. When
> mythfrontend first starts up, it is responsive to input from keyboard
> and lirc remote. After playing a recording (which has no significant
> performance problems), moving through the recordings list is much
> slower. Going back to the top level menu, then back to the recordings
> list doesn't always fix the problem, though restarting mythfrontend
> always does. Navigating to certain other menus, such as system status,
> seems to reset mythfrontend to its responsive state.
> I have been seeing this problem starting with 0.19, then on 0.20, and
> now on SVN from a few days ago. I have thought it could be CPU load,
> video driver, or permissions related, but I believe I've eliminated all
> those possibilities. This problem seems unrelated to what else is
> happening on the system. The CPU is an Athlon64 x2 3800, which has no
> trouble playing back HD recordings. The video card is a Radeon 9600 with
> Xorg's radeon driver, which handles video playback fine. There are two
> drives, one WDC SATA drive and one Seagate UATA-100 drive, set as master
> by itself.
> There is one filesystem for recordings on each disk (using the new
> storage groups feature), and both frontend and backend users can read
> and write to both locations. The Seagate drive spins down most of the
> time, since it only contains recordings. There is an additional delay
> while it spins up, but I was already aware of this and it's unrelated to
> my ongoing problem. I tried removing all the PNG thumbnails. Recreating
> them introduced additional delays, but after that was done, the problem
> I'm trying to fix is still there.
> Based on my observations, I think it has to be a problem within
> mythfrontend, since it seems to only depend on its internal state. I'm
> wondering if it could have something to do with mythfrontend's MySQL
> connections. Or, perhaps it's somehow related to running on an SMP
> system. I also have a separate MythTV system with only a Duron 800, one
> UATA hard drive, and a PVR-350 for output. It's running 0.20. Though it
> has much lower overall performance, it doesn't have the slow recordings
> menu problem and generally performs quite well for an SD Mythbox.
> Jonathan Rogers
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> mythtv-users at mythtv.org
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The only thing we have in common hardware-wise is a dual core AMD CPU. 
I think there is no doubt at all that it is a bug in mythfrontend, and that it has been around for a long time - I've mentioned it various times on this list, but nobody seems to be interested. 
Since I can't be bothered getting into a flame war with the amateur programmers on this list (who will deny that there's any possibility of there being any bugs in myth due to the godlike status of isaac et al) or with the pros (who will tell me to fix it myself instead of whinging), I decided to live with it, since I don't have time to debug the problem. 

However, if anyone wants info from me about it (e.g. my hardware setup, or specific behaviour that I observe), I'm happy to supply it.

If anyone cares, I've described the symptoms in reasonable detail in the past. There seems to be a threading issue with the removal of the video preview display on the watch recordings screen which causes one CPU to max out when changing selection (and hence changing video preview). When it works properly, the preview disappears, and is replaced a short time later with the preview for the newly selected show. It is possible in this state to move selection before the preview appears.
When it is not working properly, the preview for the previous show remains present (but seemingly paused), before the preview for the next selection appears. The problem is that the selection cannot be changed until the new preview appears, so moving selection becomes very slow. 

My bet is that there is supposed to be a short sleep before displaying the new preview to allow the user to move swiftly on, but that this sleep is somehow failing to work after exiting back to this menu from watching a recording.

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