Threaded video freezes RA on i3-7100U + Intel HD 620 with Kubuntu 18.04.1

[Clyde]

Hi,

on my MSI Cubi 3 Silent mini pc running Kubuntu 18.04.1, enabling video_threaded = "true" causes RetroArch to freeze so hard that I have to kill it with killall -9 retroarch. This happens every time. Sometimes, the freeze only affects the graphics and the game seems to continue in the background, according to the non-looping sound. If that happens, exiting with Hotkey+Start freezes RA completely like described above.

Pi Model or other hardware: Kaby Lake i3-7100U CPU + Intel Graphics HD 620
RetroPie Version Used (eg 3.6, 3.8.1, 4.1 - do not write latest): 4.4
Built From: manual installation on top of Kubuntu 18.04.1
USB Devices connected: 3-button mouse + Logitech keyboard
Controller used: Logitech USB keyboard + Qumox Wii U Pro bluetooth controller
Error messages received: none
Log found in /dev/shm/runcommand.log (if relevant): https://pastebin.com/F8WgSCqT
Emulator: presumably all libretro, tested: lr-snes9x2010, lr-mame2016, lr-fbalpha
How to replicate the problem: Set video_threaded = "true" and run a game. If enabled in a running game, it freezes as soon as I leave the RA gui.

Any help is very appreciated. I want to try threaded video to fix microlag in 2D scrolling on the Cubi 3 that I don't have on my Pi with threaded video.

The only thing I found on the web is this thread in the Libretro forum. It sounds similar to my problem, but alas, has no solution.

Cheers
Clyde

[BuZz]

@Clyde You will have to report this to the retroarch github tracker if it isn't already on there. I seem to remember something that it had issues on some systems.

Generally you don't want to use this option on a PC. It may well not fix the scrolling issue anyway.

[mitu]

There are a few issues with threaded video on Linux in the RetroArch tracker (an active one is here, but there's been several closed, like this one).
The issue you're seeing now has been reported here a lot of times after Ubuntu 18.04 got released - which coincided with the 4.4 release of RetroPie. I've followed up on this after a system update in Ubuntu 16.04 has produced the same problem (see this topic). Consequently this options has been disabled in RetroPie in Ubuntu, since - according to the docs for Libretro - would only help the performance on low powered devices (such as the Pi).

Regarding your issue, as @BuZz said, you might be comparing oranges and apples - the Linux OpenGL video driver with the PI's OpenGL ES (EGL) video driver. If you want to check out if it fixes your issue, you can try an Ubuntu 16.04 install (without updates) just to avoid the system updates that triggered this behavior.

[Clyde]

@BuZz @mitu Thank you both for all that information. I still have two 14.04 installations I could install Retropie on, and test threaded video there. But it may already enough for me to know that it probably won't help me with my scrolling problem anyway.

I already planned to open a separate thread about the latter, but I wanted to check beforehand if threaded video may be the solution. With the knowledge you gave me, I may do that in the next days (right now, I'm too tired 😴 ).

Would you still recommend that I report my case of this apparently already well known issue to the RA bugtracker, or would you say that the existing reports are enough, and we (who are affected by this) will just have to be patient?

[mitu]

@Clyde You could add the info to an existing issue or open a new one, but I'd test before using a 'standalone' RetroArch (they provide 'flatpak' packages to install easily the latest version) and maybe modifying the build script in RetroPie-Setup to get the latest version of RA to compile.