• LightDM 100% CPU use AFTER logging out.


    Hey everyone!

    So this is an issue I’ve been dealing with for a few weeks now. Basically, I moved all of my servers over to Antergos from Gentoo/Debian and I’ve got this really nagging issue with LightDM. After logging out, my CPU jumps to 100%.

    1  [|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||  88.0%]     Tasks: 39, 53 thr; 4 running
      2  [|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||  88.8%]     Load average: 1.72 0.77 0.32
      Mem[|||||||||||||||||||||||||||||||||||                        206/997MB]     Uptime: 00:11:11
      Swp[                                                            0/2855MB]
    
      PID USER      PRI  NI  VIRT   RES   SHR S CPU% MEM%   TIME+  Command
      679 lightdm    20   0 2612M  146M 85268 S 122. 14.7  2:41.47 /usr/lib/webkit2gtk-4.0/WebKitWebProcess 18
      694 lightdm    20   0 2612M  146M 85268 R 54.8 14.7  1:09.73 /usr/lib/webkit2gtk-4.0/WebKitWebProcess 18
      693 lightdm    20   0 2612M  146M 85268 S 49.5 14.7  1:06.26 /usr/lib/webkit2gtk-4.0/WebKitWebProcess 18
      620 root       20   0  296M 45044 26240 S 47.6  4.4  1:01.17 /usr/lib/xorg-server/Xorg :0 -seat seat0 -auth /run/lightdm/root/:0 -nolisten tcp vt7 -novtsw
      648 lightdm    20   0 1864M 69908 54192 S  5.8  6.8  0:07.85 /usr/sbin/lightdm-webkit2-greeter
      713 chris      20   0 14364  3628  2692 R  0.0  0.4  0:00.03 htop
        1 root       20   0 34592  5020  3612 S  0.0  0.5  0:01.13 /sbin/init
    

    I’ve been able to reproduce this in 4 separate instances: 2 VM’s (seedbox/minecraft) and 2 physical machines (HTPC/laptop).

    Everything works as expected until I log out the first time and that’s when the CPU jumps to 100%. The workaround I’ve been using is to log in via ssh and kill the top LightDM process. This effectively locks me out of the system (which is fine because I connect to the VMs mostly via x2go.)

    Has anyone experienced this or know of any fix? I’ve searched the forums/net and can’t find anything related except for a bug that was tracked in Ubuntu a few years ago.

    Here are the LightDM logs according to the stickied post.

  • have you tried just reinstalling lightdm? or maybe tried a different dm, say mdm?

  • @Lizzi Just reinstalled after you suggested it. The problem persists.

    I’ll look into installing another DM, but I’d ideally like to get get this LightDM issue resolved.

  • thats too bad. hoping to get lucky.

    askimet is preventing me from posting a link to the blog about lightdm.conf. I wonder if there is a script that runs when x starts that might be causing this. Maybe google mattfischer?

  • ive got to say i am a bit confused.how is it that after you’ve logged out of your desktop that you can tell how much cpu use is going on? After logging out of the desktop shouldnt you be at the lightdm greeter, aka login screen?

  • also which lightdm greeter do you have installed?

  • @Lizzi said:

    ive got to say i am a bit confused.how is it that after you’ve logged out of your desktop that you can tell how much cpu use is going on? After logging out of the desktop shouldnt you be at the lightdm greeter, aka login screen?

    I use ssh on another computer to access the command line.

    ssh [email protected]
    htop
    

    That’s what I used to get the output you see there. (ALSO: This happens to be a VM that I have in Proxmox and that also reports the high CPU usage, which is how I discovered it in the first place.)

    And it’s the Antgeros default LightDM. No idea what that is - these are clean installs with issues. This is the oldest of them but each subsequent install has the same issue. That’s what leads me to believe it’s an issue with the default install in Antergos.

  • Fast forward to 2017 and the problem of LightDM Login Screen pushing Core i7 to 50% load didn’t go away. Are developers on permanent vacation?

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