xorg stopped responding to keyboard. Killing xorg "fixed" it

[teo1978]

I booted Ubuntu, and when I started using it, nothing would respond to the keyboard. Everything was responding normally to the mouse.
It looked like the keystrokes were being "buffered" extremely slowly, I'll explain:

For example, I opened Chrome and I started typing "facebook" in the address bar, but no character showed up, as if the keyboard wasn't even connected (however, I had used the same keyboard to type my password to log in and that had worked).

So I opened a terminal, and then the characters "fa" showed up on the command line: that is two of the several characters that I had typed almost a minute before into another application.

Then I started hitting keys randomly on my keyboard, like "lksjdbljb", and opening several applications (e.g. open Thunderbird, click "new message" - remember, the mouse was responding - and type random characters into the "to" address). With several seconds of delay, some other random characters that I had typed minutes before in another app would show up.

That is, keyboard totally unusable, as if the keystroke buffer was slow. And this would happen with both the laptop's builtin keyboard and the external one connected via USB.

I hit Ctrl+Alt+F1 (which responded immediately) to open a virtual terminal. I logged in on the virtual terminal, where the keyboard(s) would respond perfectly.
I ran "top", and there was no process consuming an abnormal amount of CPU.

I tried killing the "at-spi2-registr" process which was second in the list with like 2% CPU consumption and had caused me problems before (see #1772109), but that didn't help (I switched back to my xorg session via ctrl+alt+f7 and the keyboard was still berserk there).

So finally I killed xorg, which obviously logged me out, and after I logged back in everything was working normally.

About half of the fucking times I boot or reboot, the system is unusable due to some bug like this. Now this is a new one. Fucking pathetic.

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: xorg 1:7.7+13ubuntu3
ProcVersionSignature: Ubuntu 4.4.0-124.148-generic 4.4.117
Uname: Linux 4.4.0-124-generic x86_64
NonfreeKernelModules: nvidia_uvm nvidia
.proc.driver.nvidia.gpus.0000.01.00.0: Error: [Errno 21] Is a directory: '/proc/driver/nvidia/gpus/0000:01:00.0'
.proc.driver.nvidia.registry: Binary: ""
.proc.driver.nvidia.version:
 NVRM version: NVIDIA UNIX x86_64 Kernel Module 340.104 Thu Sep 14 17:13:13 PDT 2017
 GCC version: gcc version 5.4.0 20160609 (Ubuntu 5.4.0-6ubuntu1~16.04.9)
.tmp.unity_support_test.0:

ApportVersion: 2.20.1-0ubuntu2.17
Architecture: amd64
CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins'
CompositorRunning: compiz
CompositorUnredirectDriverBlacklist: '(nouveau|Intel).*Mesa 8.0'
CompositorUnredirectFSW: true
CurrentDesktop: Unity
Date: Fri Jun 1 15:59:54 2018
DistUpgraded: Fresh install
DistroCodename: xenial
DistroVariant: ubuntu
DpkgLog:

ExtraDebuggingInterest: Yes, if not too technical
GraphicsCard:
 Intel Corporation 3rd Gen Core processor Graphics Controller [8086:0166] (rev 09) (prog-if 00 [VGA controller])
   Subsystem: Acer Incorporated [ALI] 3rd Gen Core processor Graphics Controller [1025:0647]
 NVIDIA Corporation GF117M [GeForce 610M/710M/810M/820M / GT 620M/625M/630M/720M] [10de:1140] (rev a1) (prog-if 00 [VGA controller])
   Subsystem: Acer Incorporated [ALI] GeForce 710M [1025:0691]
InstallationDate: Installed on 2013-10-11 (1693 days ago)
InstallationMedia: Ubuntu 13.04 "Raring Ringtail" - Release amd64 (20130424)
MachineType: Acer Aspire V3-571G
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.4.0-124-generic.efi.signed root=UUID=5830b30e-69e8-4bb4-8a2b-bc2b43c7414a ro quiet splash vt.handoff=7
SourcePackage: xorg
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 10/15/2012
dmi.bios.vendor: Acer
dmi.bios.version: V2.07
dmi.board.asset.tag: Type2 - Board Asset Tag
dmi.board.name: VA50_HC_CR
dmi.board.vendor: Acer
dmi.board.version: Type2 - Board Version
dmi.chassis.type: 10
dmi.chassis.vendor: Acer
dmi.chassis.version: V2.07
dmi.modalias: dmi:bvnAcer:bvrV2.07:bd10/15/2012:svnAcer:pnAspireV3-571G:pvrV2.07:rvnAcer:rnVA50_HC_CR:rvrType2-BoardVersion:cvnAcer:ct10:cvrV2.07:
dmi.product.name: Aspire V3-571G
dmi.product.version: V2.07
dmi.sys.vendor: Acer
version.compiz: compiz 1:0.9.12.3+16.04.20180221-0ubuntu1
version.ia32-libs: ia32-libs N/A
version.libdrm2: libdrm2 2.4.83-1~16.04.1
version.libgl1-mesa-dri: libgl1-mesa-dri 17.2.8-0ubuntu0~16.04.1
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx 17.2.8-0ubuntu0~16.04.1
version.nvidia-graphics-drivers: nvidia-graphics-drivers-* N/A
version.xserver-xorg-core: xserver-xorg-core 2:1.18.4-0ubuntu0.7
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:2.10.1-1ubuntu2
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:7.7.0-1
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.917+git20160325-1ubuntu1.2
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.12-1build2
xserver.bootTime: Fri Jun 1 15:59:16 2018
xserver.configfile: /etc/X11/xorg.conf
xserver.errors:
 NVIDIA(0): Failed to initiate mode change.
 NVIDIA(0): Failed to complete mode change
xserver.logfile: /var/log/Xorg.0.log
xserver.version: 2:1.18.4-0ubuntu0.7

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Paul White (paulw2u)]

Ubuntu 16.04 (xenial) reached end-of-standard-support on April 29, 2021.

The reporter no longer uses Launchpad so will change status to 'Invalid'

If anyone else sees that this is still an issue when using a currently
supported release of Ubuntu then please tell us in which one(s) and
change the status back to 'Confirmed'.