xflock4 does not turn off screen due to lack of sleep
Submitted by Chris Bainbridge
Assigned to Simon Steinbeiß @ochosi
Description
As noted at http://www.shallowsky.com/linux/x-screen-blanking.html calls to "xset dpms" need to be prefixed with "sleep 1":
will blank the screen (or activate the screensaver program, if you're using
one) after a delay of one second. You need the delay because X gets a little
confused about the order of events; it will blank the screen but immediate
un-blank it, thinking the activity of your typing the command happened
recently enough to come out of screensaver mode.
sleep 1; xset dpms force off
will turn the screen OFF after a delay of one second. You can also use
standby, suspend, or on instead of off.Downstream bug report: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=776674
Version: 4.10.1
Activity
Patch 5915, "xflock4-sleep.patch":
xflock4-sleep.patch-
@Steve Yes the patch works for me using slock. What exactly fails for you? Does "sleep 1; xset dpms force off" successfully turn off the monitors on your system? Do you have one of {xscreensaver-command,light-locker-command,gnome-screensaver-command} installed? If so, the xset dpms line in xflock4 is never executed.
(can't seem to change bug status back from needinfo..)
-
Ok, I've been a bit silly on that one. So, when having slock installed I reach this code path.
With the patch: 1 second delay, then a black screen Without the patch: black screen immediately
Now, on desktops, when using a mouse, it's quite easy to trigger the mouse after the screen has been forced off. Still, a whole second is a bit excessive.
I'd like more developers to weight in before applying the patch.
-
Chris, thanks for writing the patch and bearing with me though. Of course if you can link to others complaining about the issue, and to more precise reasons why it is systematically happening for you, it'll increase the odds of people weighing in favour of your patch.
-
With the patch: 1 second delay, then a black screen Without the patch: black screen immediately
slock will always show a black screen but is the monitor actually turned off with DPMS - my monitor shows "Entering power save mode" when this happens and turns off the back light.
Try this: in a terminal type "xset dpms force off" and press and hold the enter key for one second before releasing it. The key press event will cause the execution of the xset command, but then the release event will wake the monitor back up. The same happens with the ctrl-alt-delete shortcut.
Of course if you can link to others complaining about the issue
http://www.shallowsky.com/linux/x-screen-blanking.html http://askubuntu.com/questions/38776/trigger-screensaver-off-monitor https://wiki.archlinux.org/index.php/Display_Power_Management_Signaling http://ubuntuforums.org/showthread.php?t=1317747&page=4 http://unix.stackexchange.com/questions/4466/screen-turns-on-automatically-xset-dpms-force-off
The explanation:
"You're using it manually from command line or xset is binded to some keyboard shortcut? On my brother laptop this command was binded to some keys and after that monitor was turned off and on again, because when he was releasing key next event was emitted. Turning it off after quick sleep solved problem: perl -e 'select(undef,undef,undef,.1)' && xset dpms force off - this perl expression do sleep for 0.1 sec."
The timeout has to be longer than the delay between a person pressing the enter key and then releasing it.
-
Also see:
https://bugzilla.redhat.com/show_bug.cgi?id=1175015
This is a real pain with my notebook screen not going off when locked. In a hotel room at night, I have to put a towel over the screen to get to sleep myself! When at my desk at home, the external monitor is brightly lit when locked, lighting up the whole room at night.
I am concerned about long-term effects on the backlight feature failing if not corrected.
Since I am running Fedora 21, please let me know what I have to do to test a patch.
thank you
-
Same problem with:
Fedora-Xfce-armhfp-22-20150223-sda.raw.xz
On my Cubietruck through its VGA adapter. I probably will get around to testing with HDMI tomorrow as well as testing on my Cubieboard2.
The usual: You set screensaver to use a blank screen, and lock the screen.
Screen blanks, but backlight stays on.
-
Still happening in Xubuntu 18.10. I vote for adding the patch!
$ hostnamectl Static hostname: CKR-2 Icon name: computer-laptop Chassis: laptop Machine ID: 5c61c71187fa4ba4aa26bdd89516ee5a Boot ID: 9a2e3fb61f6d461d9b423cdeebaa4c57 Operating System: Ubuntu 18.10 Kernel: Linux 4.18.0-10-generic Architecture: x86-64
-
@Simon: apologies, if your previous comment is directed at me. I'm currently on Ubuntu 19.04(Gnome 3) without a proper XFCE4 installation to test this on.
-
I do not see a problem in having even longer delay than a second. But, using "sleep 1; xset dpms force off" has still the problem that user may accidentally touch something so that display will become on again. Besides, it effectively disables Presentation mode user may have set using Power manager's panel item.
A better solution would be to change DPMS settings for the time such a screen locker is running to enable turning display off after reasonable time of inactivity from user, and restore previous settings, when user unlocks. This is possible by using a wrapper script.
I have actually introduced such a version of xflock4 in bug report https://bugzilla.xfce.org/show_bug.cgi?id=10217 attachment https://bugzilla.xfce.org/attachment.cgi?id=7254 in 2017. It uses 15 second delay, but an initial delay of 1 second could be added.
That script has other modifications such as added screensavers and lockers and optionally using display power management for the locker user may have set in Xfconf. The script can be simplified notably, if hacking the DPMS settings for general lock command set in Xfconf is left out.
I have never got any feedback about the script.
Note: proper screensavers (that have a daemon running when lock command is called) should handle DPMS by themselves.
As for the previous attachment, at least with the gnome-screensaver available for Ubuntu 20.04 (version 3.6.1-11ubuntu4) 'gnome-screensaver-command --lock' exits with status 0 even if gnome-screensaver is not running so the script exits with 0 even if it does not lock the screen. One option is to remove gnome-screensaver from the script (see issue #17 (closed)) or to handle checking by 'gnome-screensaver-command --query'.
added 5. Locker / Screensaver Patch labels
added 4. Shell label
