Compiz uses 100% CPU when desktop is locked

[LGB [Gábor Lénárt]]

Tested on three different machines upgraded to Ubuntu 15.10 recently. All of them are 32 bit systems, two of them are intel based integrated GPU (on of them is notebook) with intel CPU, and one is AMD APU equipped machine with the binary driver (so because of this, I don't think it's a video driver related issue). The problem: I've noticed that after locking the screen the fan of the notebook starts to produce a louder noise, typical sign of high CPU usage. After logging in into the machine via ssh from another one, I found that compiz uses 100% CPU, but after unlock the CPU usage drops below 1%. Then I noticed the same with two desktop machines, the same: 100% used CPU by compiz when locked. It's really annoying since it didn't happen with the previous Ubuntu release, and it creates significant noise by the fans, and of course - I guess - using more energy than it should.

ProblemType: Bug
DistroRelease: Ubuntu 15.10
Package: compiz 1:0.9.12.2+15.10.20151015-0ubuntu1
ProcVersionSignature: Ubuntu 4.2.0-18.22-generic 4.2.3
Uname: Linux 4.2.0-18-generic i686
.tmp.unity.support.test.0:

ApportVersion: 2.19.1-0ubuntu4
Architecture: i386
CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins'
CompositorRunning: compiz
CompositorUnredirectDriverBlacklist: '(nouveau|Intel).*Mesa 8.0'
CompositorUnredirectFSW: true
CurrentDesktop: Unity
Date: Sat Nov 14 21:53:55 2015
DistUpgraded: 2015-10-18 23:18:25,282 INFO cache.commit()
DistroCodename: wily
DistroVariant: ubuntu
DkmsStatus:
 virtualbox, 5.0.4, 4.2.0-17-generic, i686: installed
 virtualbox, 5.0.4, 4.2.0-18-generic, i686: installed
GraphicsCard:
 Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller [8086:0116] (rev 09) (prog-if 00 [VGA controller])
   Subsystem: Lenovo Device [17aa:21dd]
InstallationDate: Installed on 2012-03-03 (1351 days ago)
InstallationMedia: Ubuntu 11.04 "Natty Narwhal" - Release i386 (20110427.1)
MachineType: LENOVO 5016NW6
PackageArchitecture: all
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.2.0-18-generic root=UUID=8df578aa-47e3-483f-b694-bf7effd24b7d ro i915.semaphores=0 quiet splash vt.handoff=7
SourcePackage: compiz
UpgradeStatus: Upgraded to wily on 2015-10-18 (26 days ago)
dmi.bios.date: 11/04/2011
dmi.bios.vendor: LENOVO
dmi.bios.version: 8GET38WW (1.15 )
dmi.board.name: 5016NW6
dmi.board.vendor: LENOVO
dmi.board.version: Not Available
dmi.chassis.asset.tag: No Asset Information
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: Not Available
dmi.modalias: dmi:bvnLENOVO:bvr8GET38WW(1.15):bd11/04/2011:svnLENOVO:pn5016NW6:pvrThinkPadL520:rvnLENOVO:rn5016NW6:rvrNotAvailable:cvnLENOVO:ct10:cvrNotAvailable:
dmi.product.name: 5016NW6
dmi.product.version: ThinkPad L520
dmi.sys.vendor: LENOVO
version.compiz: compiz 1:0.9.12.2+15.10.20151015-0ubuntu1
version.libdrm2: libdrm2 2.4.64-1
version.libgl1-mesa-dri: libgl1-mesa-dri 11.0.2-1ubuntu4
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx 11.0.2-1ubuntu4
version.xserver-xorg-core: xserver-xorg-core 2:1.17.2-1ubuntu9
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:2.9.2-1ubuntu1
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:7.5.0+git20150819-0ubuntu1
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.917+git20150808-0ubuntu4
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.11-1ubuntu3
xserver.bootTime: Fri Nov 13 17:02:38 2015
xserver.configfile: default
xserver.errors:

xserver.logfile: /var/log/Xorg.0.log
xserver.outputs:
 product id 9196
 vendor AUO
xserver.version: 2:1.17.2-1ubuntu9

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Alberto Salvia Novella (es20490446e)]

Heat is good at winter time.

[LGB [Gábor Lénárt] (lgb)]

I am not sure if it's related, but another interesting fact: I left my Ubuntu box switched on at my workplace, though I can access it via ssh (and sshfs to mount my home from there). It was more than a week, not to go to work, more than usual. Screen is locked of course. One thing, the usual: with utilizing ssh I see that compiz process uses about 100% of the CPU all the time. Other thing: when I went back to work, I realized that compiz used 41% of the memory ... So there is some memory leak as well somewhere. Now I see, that I often have to use "nohup compiz --replace &" from a terminal (since I don't want to lose the state of my desktop) every several days, since compiz starts to eat simply too much memory. After such a compiz replacement, it goes back to the "normal" and usual memory consumption. As far as I can tell, compiz seems a disaster for me, both of CPU and memory usage problems all the time, at total of three different machines I use, so I don't think it's just a problem at a given setup too much :(

[LGB [Gábor Lénárt] (lgb)]

Sorry, one more important thing to note: the 100% CPU usage goes almost instantly after locking screen regardless of "freshly booted" system or switched on since a week, the memory leaking (what I talked about in my previous comment) is just another interesting fact which may or may not be related, I don't know.