dual monitor instability

[jesteria]

Environment

Distribution

$ cat /etc/os-release
NAME="Pop!_OS"
VERSION="18.04 LTS"
ID=ubuntu
ID_LIKE=debian
PRETTY_NAME="Pop!_OS 18.04 LTS"
VERSION_ID="18.04"
HOME_URL="https://system76.com/pop"
SUPPORT_URL="http://support.system76.com"
BUG_REPORT_URL="https://github.com/pop-os/pop/issues"
PRIVACY_POLICY_URL="https://system76.com/privacy"
VERSION_CODENAME=bionic
UBUNTU_CODENAME=bionic

Monitors

$ xrandr
Screen 0: minimum 320 x 200, current 3120 x 1920, maximum 8192 x 8192
eDP-1 connected (normal left inverted right x axis y axis)
   3200x1800     60.00 +  59.96    59.94    48.01  
   2880x1620     59.96    59.97  
   2560x1600     59.99    59.97  
   2560x1440     59.99    59.99    59.96    59.95  
   2048x1536     60.00  
   1920x1440     60.00  
   1856x1392     60.01  
   1792x1344     60.01  
   2048x1152     59.99    59.98    59.90    59.91  
   1920x1200     59.88    59.95  
   1920x1080     60.01    59.97    59.96    59.93  
   1600x1200     60.00  
   1680x1050     59.95    59.88  
   1600x1024     60.17  
   1400x1050     59.98  
   1600x900      59.99    59.94    59.95    59.82    60.00  
   1280x1024     60.02  
   1440x900      59.89  
   1400x900      59.96    59.88  
   1280x960      60.00  
   1440x810      60.00    59.97  
   1368x768      59.88    59.85  
   1360x768      59.80    59.96  
   1280x800      59.99    59.97    59.81    59.91  
   1152x864      60.00  
   1280x720      60.00    59.99    59.86    59.74  
   1024x768      60.04    60.00  
   960x720       60.00  
   928x696       60.05  
   896x672       60.01  
   1024x576      59.95    59.96    59.90    59.82  
   960x600       59.93    60.00  
   960x540       59.96    59.99    59.63    59.82  
   800x600       60.00    60.32    56.25  
   840x525       60.01    59.88  
   864x486       59.92    59.57  
   800x512       60.17  
   700x525       59.98  
   800x450       59.95    59.82  
   640x512       60.02  
   720x450       59.89  
   700x450       59.96    59.88  
   640x480       60.00    59.94  
   720x405       59.51    58.99  
   684x384       59.88    59.85  
   680x384       59.80    59.96  
   640x400       59.88    59.98  
   576x432       60.06  
   640x360       59.86    59.83    59.84    59.32  
   512x384       60.00  
   512x288       60.00    59.92  
   480x270       59.63    59.82  
   400x300       60.32    56.34  
   432x243       59.92    59.57  
   320x240       60.05  
   360x202       59.51    59.13  
   320x180       59.84    59.32  
DP-1 disconnected (normal left inverted right x axis y axis)
HDMI-1 connected 1200x1920+1920+0 left (normal left inverted right x axis y axis) 518mm x 324mm
   1920x1200     59.95*+
   1920x1080     60.00  
   1600x1200     60.00  
   1680x1050     59.88  
   1280x1024     60.02  
   1280x960      60.00  
   1024x768      60.00  
   800x600       60.32  
   640x480       59.94  
   720x400       70.08  
HDMI-2 connected primary 1920x1080+0+542 (normal left inverted right x axis y axis) 509mm x 286mm
   1920x1080     60.00*+  50.00    59.94  
   1680x1050     59.88  
   1600x900      60.00  
   1280x1024     60.02  
   1440x900      59.90  
   1280x800      59.91  
   1280x720      60.00    50.00    59.94  
   1024x768      60.00  
   800x600       60.32  
   720x576       50.00  
   720x480       60.00    59.94  
   640x480       60.00    59.94  
   720x400       70.08  

(No ~/.config/montors.xml.)

Application information

$ apt policy hidpi-daemon
hidpi-daemon:
  Installed: 18.04.4~1533160664~18.04~85d4567
  Candidate: 18.04.4~1533160664~18.04~85d4567
  Version table:
 *** 18.04.4~1533160664~18.04~85d4567 1001
       1001 http://ppa.launchpad.net/system76/pop/ubuntu bionic/main amd64 Packages
       1001 http://ppa.launchpad.net/system76/pop/ubuntu bionic/main i386 Packages
        100 /var/lib/dpkg/status

Issue/Bug Description

I have two monitors, which I hook into a Galago Pro – one into the HDMI another into the displayport.

If I very carefully and slowly connect each monitor, and wait for the daemon to reconfigure things before proceeding, (and then, as a third step, close the lid) – then it's fine. Same for disconnecting. It takes a while.

And if I am not slow/careful enough, something happens to the desktop. The system isn't entirely frozen, but that TTY is blank, and I can't interact with Gnome.

My "fix" is: killall -3 gnome-shell. I store this as an sh script in ~/bin/kick-gnome-shell, which I execute from another TTY, as needed.

(But, of course, that's not ideal; and, I don't know if others might have the same issue, but not know what to do to remediate it.)

Steps to reproduce

Connect/disconnect more than one of these monitors without waiting for the daemon to handle each event and to redraw the displays.

Expected behavior

1. gnome-shell should never be put into such a state that the TTY cannot recover (without a "kick")
2. Ideally, the daemon would recover from repeated events such that the entire process doesn't take so long, – i.e. if a second [dis]connection event occurs while it's processing the first one, it's able to immediately start over with the new state.