Horizontal lines flashing on screen briefly

[Jani Uusitalo]

Since upgrading HWE from -lts-saucy to -lts-trusty, I have had recurring graphical glitches on screen, with short black horizontal lines appearing briefly on screen (on top of normal contents), particularly when switching between applications. The lines appear only for a few 100 ms before going away (just enough to register in your eye that there's something there), so I've been trying to make a screen recording to capture it, but of course the phenomenon goes away when I do (perhaps RecordMyDesktop does something with the screen that makes it less likely to appear).

I don't recall seeing this with -lts-saucy or other previous Xorg packages. It was so obvious right after upgrading that either it never occurred before or was so rare or quick to flash away that it didn't register.
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.tmp.unity.support.test.0:

ApportVersion: 2.0.1-0ubuntu17.9
Architecture: amd64
CompizPlugins: [core,composite,opengl,compiztoolbox,decor,gnomecompat,snap,imgpng,unitymtgrabhandles,move,place,grid,resize,mousepoll,vpswitch,regex,winrules,wall,session,animation,workarounds,expo,ezoom,fade,scale,unityshell]
CompositorRunning: compiz
DistUpgraded: 2014-07-11 11:04:24,254 DEBUG running doUpdate() (showErrors=True)
DistroCodename: precise
DistroRelease: Ubuntu 12.04
DistroVariant: ubuntu
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ExtraDebuggingInterest: Yes,
GraphicsCard:
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   Subsystem: ASUSTeK Computer Inc. Device [1043:84ca]
InstallationMedia: Ubuntu 9.10 "Karmic Koala" - Release amd64 (20091027)
MachineType: System manufacturer System Product Name
MarkForUpload: True
Package: xorg 1:7.6+12ubuntu2
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ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.13.0-53-generic root=UUID=28b993a2-7b5f-45fb-9062-173b0759a0ee ro crashkernel=384M-2G:64M,2G-:128M quiet splash vt.handoff=7
ProcVersionSignature: Ubuntu 3.13.0-53.89~precise1-generic 3.13.11-ckt19
Tags: precise running-unity ubuntu compiz-0.9
Uname: Linux 3.13.0-53-generic x86_64
UpgradeStatus: Upgraded to precise on 2014-07-11 (318 days ago)
UserGroups: adm bluetooth cdrom dip lpadmin plugdev sambashare ssh sudo vboxusers
dmi.bios.date: 10/17/2014
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: 1505
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dmi.board.vendor: ASUSTeK COMPUTER INC.
dmi.board.version: Rev X.0x
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dmi.chassis.type: 3
dmi.chassis.vendor: Chassis Manufacture
dmi.chassis.version: Chassis Version
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvr1505:bd10/17/2014:svnSystemmanufacturer:pnSystemProductName:pvrSystemVersion:rvnASUSTeKCOMPUTERINC.:rnP8H77-MPRO:rvrRevX.0x:cvnChassisManufacture:ct3:cvrChassisVersion:
dmi.product.name: System Product Name
dmi.product.version: System Version
dmi.sys.vendor: System manufacturer
version.compiz: compiz 1:0.9.7.12-0ubuntu4
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version.libdrm2: libdrm2 2.4.52-1~precise2
version.libgl1-mesa-dri: libgl1-mesa-dri N/A
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version.libgl1-mesa-glx: libgl1-mesa-glx N/A
version.xserver-xorg-core: xserver-xorg-core N/A
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev N/A
version.xserver-xorg-video-ati: xserver-xorg-video-ati N/A
version.xserver-xorg-video-intel: xserver-xorg-video-intel N/A
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau N/A

[Jani Uusitalo (uusijani)]

Ha, finally caught a couple of glimpses of this in a screen recording! Attaching it here.

[Jani Uusitalo (uusijani)]

Also, here's a screenshot (from the video) with the artifacts visible. I notice they seem to cover mostly just Chromium's content area, but just last night I had this occur just as I was logging out (with the lines remaining on screen until I tried to take a screenshot), with nothing but the log out confirmation running on top of my desktop, so it's probably not just Chromium that's causing this.

[Jani Uusitalo (uusijani)]

I take that back, it seems to have been caused by Chromium all along (more specifically either #threaded-compositing-mode or #deadline-scheduling), despite those glitches appearing outside of Chromium too. Sot it's a Chromium bug, but I'm too lazy to debug this further (the issue goes away with those configuration flags set to default) so I'll just mark this as invalid.

[Jani Uusitalo (uusijani)]

Reopening. It didn't go away after all, looks like the occurrence varies (didn't see it yesterday), perhaps those Chromium settings just made it more probable.

[Jani Uusitalo (uusijani)]

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[Jani Uusitalo (uusijani)]

Hi Christopher, the apport-collected data above was gathered from my main desktop, which only has Intel graphics. (I mentioned the other system with Radeon just because it *didn't* suffer from this problem despite having the same software. I no longer have access to that system so unfortunately I can't provide the same logs from it for comparision.)

[penalvch (penalvch)]

Jani Uusitalo, to see if this is already resolved in a later version of Ubuntu, could you please test for this via http://cdimage.ubuntu.com/daily-live/current/ and advise to the results?

[Jani Uusitalo (uusijani)]

I can, but it'll be hard to get definitive evidence as the phenomenon can be quite elusive, and I cannot run the daily for very long periods (as it gets in the way of productivity). Obviously, if I catch it even once on the daily, it'll be proof enough that the issue persists, but on the other hand, not seeing the issue may just mean it didn't happen to occur during the time running from the daily.

(Upgrading the system to latest release would be a surer way to find out, but for now I intend to keep running 12.04 until the next LTS, 16.04.)

[Launchpad Janitor (janitor)]

[Expired for xorg (Ubuntu) because there has been no activity for 60 days.]

[Jani Uusitalo (uusijani)]

Just adding a note that this does still occur under 14.04, to which I recently upgraded. Naturally this was to be expected, given that the issue first occurred after switching to the Trusty HWE pack in 12.04.

[Jani Uusitalo (uusijani)]

Haven't seen this once since upgrading to 16.04 back in April, so I'm pretty sure the issue has been fixed. Yay!