My Ubuntu 18.04 GUI seems frozen

[Thomas A. F. Thorne]

This will possibly be a duplicate of Bug #1820028 or Bug #1820028

I was trying to report a frozen GUI over SSH. This is the second report that apport-cli generated when I ran it with lightdm as the target package.

The symptoms I see are that I started running a go test last night and my GUI on Ubuntu 18.04 seems to have frozen. I cannot get the wireless mouse or keyboard to move anything on the display and the time shown on the clock matches when things froze last night.

Before I made the report I looked for any process using high amounts of CUP with top and htop but spotted none. I tried to local a SIGTERM the go test process but that made no difference.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: lightdm 1.26.0-0ubuntu1
ProcVersionSignature: Ubuntu 4.15.0-45.48-generic 4.15.18
Uname: Linux 4.15.0-45-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.5
Architecture: amd64
Date: Thu Mar 14 09:09:36 2019
InstallationDate: Installed on 2017-11-16 (482 days ago)
InstallationMedia: Ubuntu 16.04.3 LTS "Xenial Xerus" - Release amd64 (20170801)
ProcEnviron:
 LANG=en_GB.UTF-8
 TERM=xterm
 LANGUAGE=en_GB:en
 PATH=(custom, no user)
 SHELL=/bin/bash
SourcePackage: lightdm
UpgradeStatus: Upgraded to bionic on 2018-07-27 (229 days ago)