Public bug reported:

On a fresh installation of Ubuntu 20.04 with no configuration files
changed yet (the "install third-party software" option enabled),
installed from the official daily ISO, the system freezes for about a
second every 5-10 seconds and I see a spike to 70% or more CPU usage by
gnome-shell. I cannot see anything that shows up in `sudo journalctl
-ef` or `sudo dmesg -w` when the freezes occur. The problem reproduces
on both X11 and Wayland, although under Wayland it's more annoying since
a freeze leads to repeated keypresses of whatever key was being held
down on the keyboard at the time of the freeze.

This problem seems to have been reported at
<https://www.reddit.com/r/pop_os/comments/gwfn7l/gnome_shell_random_cpu_spikes_every_10_seconds/>
but with no plausible resolution or workaround in sight.

I tried to follow <https://superuser.com/q/1046603> to figure out what
was going on with gnome-shell, but I don't think the results seem very
helpful.

Result of `sudo perf top`:

    4.39%  libglib-2.0.so.0.6400.3          [.] g_variant_serialised_n_children
    4.26%  libc-2.31.so                     [.] __vfprintf_internal

And `sudo perf top --sort comm,dso`:

    45.28%  gnome-shell      libglib-2.0.so.0.6400.3
    17.23%  gnome-shell      libc-2.31.so

And `sudo perf record -g -p PID` for the `gnome-shell` PID:

    +   39.81%     0.01%  [unknown]                        [.] 0000000000000000
    +   14.26%     2.04%  libc-2.31.so                     [.] 
__vasprintf_internal
    +    8.61%     8.42%  libglib-2.0.so.0.6400.3          [.] 
g_variant_serialised_n_children
    +    8.51%     8.09%  libc-2.31.so                     [.] 
__vfprintf_internal

And `strace -c -p PID`:

    % time     seconds  usecs/call     calls    errors syscall
    ------ ----------- ----------- --------- --------- ----------------
     34.41    0.128602           5     22784     19837 recvmsg
     25.74    0.096215           7     13716       632 ioctl
     18.04    0.067420          10      6686           poll
      9.50    0.035523           7      4858           write
      4.56    0.017025           7      2322           writev

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: gnome-shell 3.36.4-1ubuntu1~20.04.2
ProcVersionSignature: Ubuntu 5.4.0-49.53-generic 5.4.65
Uname: Linux 5.4.0-49-generic x86_64
ApportVersion: 2.20.11-0ubuntu27.10
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: ubuntu:GNOME
Date: Fri Oct  9 07:54:43 2020
DisplayManager: gdm3
InstallationDate: Installed on 2020-10-09 (0 days ago)
InstallationMedia: Ubuntu 20.04.1 LTS "Focal Fossa" - Release amd64 (20201007)
ProcEnviron:
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/usr/bin/zsh
RelatedPackageVersions: mutter-common 3.36.6-1ubuntu0.20.04.2
SourcePackage: gnome-shell
UpgradeStatus: No upgrade log present (probably fresh install)

** Affects: gnome-shell (Ubuntu)
     Importance: Undecided
         Status: New


** Tags: amd64 apport-bug focal

** Description changed:

  On a fresh installation of Ubuntu 20.04 with no configuration files
  changed yet (the "install third-party software" option enabled),
  installed from the official daily ISO, the system freezes for about a
  second every 5-10 seconds and I see a spike to 70% or more CPU usage by
  gnome-shell. I cannot see anything that shows up in `sudo journalctl
  -ef` or `sudo dmesg -w` when the freezes occur. The problem reproduces
  on both X11 and Wayland, although under Wayland it's more annoying since
  a freeze leads to repeated keypresses of whatever key was being held
  down on the keyboard at the time of the freeze.
  
+ This problem seems to have been reported at
+ 
<https://www.reddit.com/r/pop_os/comments/gwfn7l/gnome_shell_random_cpu_spikes_every_10_seconds/>
+ but with no plausible resolution or workaround in sight.
+ 
  I tried to follow <https://superuser.com/q/1046603> to figure out what
  was going on with gnome-shell, but I don't think the results seem very
  helpful.
  
  Result of `sudo perf top`:
  
-     4.39%  libglib-2.0.so.0.6400.3          [.] 
g_variant_serialised_n_children
-     4.26%  libc-2.31.so                     [.] __vfprintf_internal
+     4.39%  libglib-2.0.so.0.6400.3          [.] 
g_variant_serialised_n_children
+     4.26%  libc-2.31.so                     [.] __vfprintf_internal
  
  And `sudo perf top --sort comm,dso`:
  
-     45.28%  gnome-shell      libglib-2.0.so.0.6400.3
-     17.23%  gnome-shell      libc-2.31.so
+     45.28%  gnome-shell      libglib-2.0.so.0.6400.3
+     17.23%  gnome-shell      libc-2.31.so
  
  And `sudo perf record -g -p PID` for the `gnome-shell` PID:
  
-     +   39.81%     0.01%  [unknown]                        [.] 
0000000000000000
-     +   14.26%     2.04%  libc-2.31.so                     [.] 
__vasprintf_internal
-     +    8.61%     8.42%  libglib-2.0.so.0.6400.3          [.] 
g_variant_serialised_n_children
-     +    8.51%     8.09%  libc-2.31.so                     [.] 
__vfprintf_internal
+     +   39.81%     0.01%  [unknown]                        [.] 
0000000000000000
+     +   14.26%     2.04%  libc-2.31.so                     [.] 
__vasprintf_internal
+     +    8.61%     8.42%  libglib-2.0.so.0.6400.3          [.] 
g_variant_serialised_n_children
+     +    8.51%     8.09%  libc-2.31.so                     [.] 
__vfprintf_internal
  
  And `strace -c -p PID`:
  
-     % time     seconds  usecs/call     calls    errors syscall
-     ------ ----------- ----------- --------- --------- ----------------
-      34.41    0.128602           5     22784     19837 recvmsg
-      25.74    0.096215           7     13716       632 ioctl
-      18.04    0.067420          10      6686           poll
-       9.50    0.035523           7      4858           write
-       4.56    0.017025           7      2322           writev
+     % time     seconds  usecs/call     calls    errors syscall
+     ------ ----------- ----------- --------- --------- ----------------
+      34.41    0.128602           5     22784     19837 recvmsg
+      25.74    0.096215           7     13716       632 ioctl
+      18.04    0.067420          10      6686           poll
+       9.50    0.035523           7      4858           write
+       4.56    0.017025           7      2322           writev
  
  ProblemType: Bug
  DistroRelease: Ubuntu 20.04
  Package: gnome-shell 3.36.4-1ubuntu1~20.04.2
  ProcVersionSignature: Ubuntu 5.4.0-49.53-generic 5.4.65
  Uname: Linux 5.4.0-49-generic x86_64
  ApportVersion: 2.20.11-0ubuntu27.10
  Architecture: amd64
  CasperMD5CheckResult: skip
  CurrentDesktop: ubuntu:GNOME
  Date: Fri Oct  9 07:54:43 2020
  DisplayManager: gdm3
  InstallationDate: Installed on 2020-10-09 (0 days ago)
  InstallationMedia: Ubuntu 20.04.1 LTS "Focal Fossa" - Release amd64 (20201007)
  ProcEnviron:
-  PATH=(custom, no user)
-  XDG_RUNTIME_DIR=<set>
-  LANG=en_US.UTF-8
-  SHELL=/usr/bin/zsh
+  PATH=(custom, no user)
+  XDG_RUNTIME_DIR=<set>
+  LANG=en_US.UTF-8
+  SHELL=/usr/bin/zsh
  RelatedPackageVersions: mutter-common 3.36.6-1ubuntu0.20.04.2
  SourcePackage: gnome-shell
  UpgradeStatus: No upgrade log present (probably fresh install)

** Attachment removed: "GsettingsChanges.txt"
   
https://bugs.launchpad.net/ubuntu/+source/gnome-shell/+bug/1899184/+attachment/5419984/+files/GsettingsChanges.txt

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You received this bug notification because you are a member of Desktop
Packages, which is subscribed to gnome-shell in Ubuntu.
https://bugs.launchpad.net/bugs/1899184

Title:
  CPU spikes and system hangs from gnome-shell every 5-10 seconds

Status in gnome-shell package in Ubuntu:
  New

Bug description:
  On a fresh installation of Ubuntu 20.04 with no configuration files
  changed yet (the "install third-party software" option enabled),
  installed from the official daily ISO, the system freezes for about a
  second every 5-10 seconds and I see a spike to 70% or more CPU usage
  by gnome-shell. I cannot see anything that shows up in `sudo
  journalctl -ef` or `sudo dmesg -w` when the freezes occur. The problem
  reproduces on both X11 and Wayland, although under Wayland it's more
  annoying since a freeze leads to repeated keypresses of whatever key
  was being held down on the keyboard at the time of the freeze.

  This problem seems to have been reported at
  
<https://www.reddit.com/r/pop_os/comments/gwfn7l/gnome_shell_random_cpu_spikes_every_10_seconds/>
  but with no plausible resolution or workaround in sight.

  I tried to follow <https://superuser.com/q/1046603> to figure out what
  was going on with gnome-shell, but I don't think the results seem very
  helpful.

  Result of `sudo perf top`:

      4.39%  libglib-2.0.so.0.6400.3          [.] 
g_variant_serialised_n_children
      4.26%  libc-2.31.so                     [.] __vfprintf_internal

  And `sudo perf top --sort comm,dso`:

      45.28%  gnome-shell      libglib-2.0.so.0.6400.3
      17.23%  gnome-shell      libc-2.31.so

  And `sudo perf record -g -p PID` for the `gnome-shell` PID:

      +   39.81%     0.01%  [unknown]                        [.] 
0000000000000000
      +   14.26%     2.04%  libc-2.31.so                     [.] 
__vasprintf_internal
      +    8.61%     8.42%  libglib-2.0.so.0.6400.3          [.] 
g_variant_serialised_n_children
      +    8.51%     8.09%  libc-2.31.so                     [.] 
__vfprintf_internal

  And `strace -c -p PID`:

      % time     seconds  usecs/call     calls    errors syscall
      ------ ----------- ----------- --------- --------- ----------------
       34.41    0.128602           5     22784     19837 recvmsg
       25.74    0.096215           7     13716       632 ioctl
       18.04    0.067420          10      6686           poll
        9.50    0.035523           7      4858           write
        4.56    0.017025           7      2322           writev

  ProblemType: Bug
  DistroRelease: Ubuntu 20.04
  Package: gnome-shell 3.36.4-1ubuntu1~20.04.2
  ProcVersionSignature: Ubuntu 5.4.0-49.53-generic 5.4.65
  Uname: Linux 5.4.0-49-generic x86_64
  ApportVersion: 2.20.11-0ubuntu27.10
  Architecture: amd64
  CasperMD5CheckResult: skip
  CurrentDesktop: ubuntu:GNOME
  Date: Fri Oct  9 07:54:43 2020
  DisplayManager: gdm3
  InstallationDate: Installed on 2020-10-09 (0 days ago)
  InstallationMedia: Ubuntu 20.04.1 LTS "Focal Fossa" - Release amd64 (20201007)
  ProcEnviron:
   PATH=(custom, no user)
   XDG_RUNTIME_DIR=<set>
   LANG=en_US.UTF-8
   SHELL=/usr/bin/zsh
  RelatedPackageVersions: mutter-common 3.36.6-1ubuntu0.20.04.2
  SourcePackage: gnome-shell
  UpgradeStatus: No upgrade log present (probably fresh install)

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