Display is not locked on Xubuntu

[Maarten Jacobs]

I recently upgraded to kernel 4.2.0-36-generic, and since then light-locker doesn't work anymore. However long I leave my machine on, it never locks.

I played around with the power management settings, to no avail.

I believe (such is my theory) that this is related to a problem with dbus (https://bugs.launchpad.net/ubuntu/+source/dbus/+bug/1587120), however in case it is not I'm opening a separate bug on light-locker specifically.

Note that I have a number of different machines all running the same version of xubuntu, and all have the same problem after the recent upgrade.

I also have a machine that is running xscreensaver, which is working fine.

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: light-locker 1.4.0-0ubuntu1
ProcVersionSignature: Ubuntu 4.2.0-36.42~14.04.1-generic 4.2.8-ckt8
Uname: Linux 4.2.0-36-generic x86_64
ApportVersion: 2.14.1-0ubuntu3.21
Architecture: amd64
CurrentDesktop: XFCE
Date: Mon May 30 11:50:27 2016
ExecutablePath: /usr/bin/light-locker
InstallationDate: Installed on 2016-03-06 (84 days ago)
InstallationMedia: Xubuntu 14.04.4 LTS "Trusty Tahr" - Release amd64 (20160217.1)
SourcePackage: light-locker
UpgradeStatus: No upgrade log present (probably fresh install)

[Maarten Jacobs (maarten256)]

I have finally been able to spend some time to dig into this more. After much trial and error, I ran xfce-power-manager from the command line (xfce4-power-manager --debug --no-daemon), and I realized the following message is being displayed over and over:

TRACE[xfpm-inhibit.c:357] xfpm_inhibit_un_inhibit(): UnHibit message received
TRACE[xfpm-inhibit.c:95] xfpm_inhibit_has_inhibit_changed(): Inhibit removed
TRACE[xfpm-inhibit.c:343] xfpm_inhibit_inhibit(): Inhibit send application name=/usr/bin/google-chrome reason=Uploading data to bn3sch020022343.gateway.messenger.live.com sender=:1.5650
TRACE[xfpm-inhibit.c:101] xfpm_inhibit_has_inhibit_changed(): Inhibit added
TRACE[xfpm-inhibit.c:357] xfpm_inhibit_un_inhibit(): UnHibit message received
TRACE[xfpm-inhibit.c:95] xfpm_inhibit_has_inhibit_changed(): Inhibit removed

Based on this, I closed my "hotmail" (mail.live.com) page in Google - and subsequently my screen locks and the screensaver engages.

If I re-open hotmail, the screen no longer locks and my displays stay on forever.

The ultimate question is why a background process can interrupt the power manager like this? This is not the expected behavior, is there either a bug in the code, or something wrong with my configuration?

[Theo Linkspfeifer (lastonestanding)]

It may be the case that Google Chrome is abusing the inhibit system.

More information can be found here:

bug 1775921
bug 1600622