I have been using KDE Neon for several months without a problem, but very recently I started having high CPU usage (around 50% when idling on a relatively high spec laptop) whenever I log in on my main user account (but not other user accounts on the same computer).

Investigating with top, it seems that the primary culprit is DBus. Using dbus-monitor releases a deluge of DBus messages, far more than I would expect to see on the system usually. Many of which seem to be related to the ActivityManager within plasmashell. Here is a random snippet that seems typical of the sort of messages being sent around

Code: Select all

signal time=1526444336.343101 sender=:1.37433 -> destination=(null destination) serial=8 path=/ActivityManager/Activities; interface=org.kde.ActivityManager.Activities; member=CurrentActivityChanged
   string "00a353b4-3f40-4eba-b35d-821d8ef6e2fb"
method call time=1526444336.343427 sender=:1.22 -> destination=org.kde.ActivityManager serial=279764 path=/ActivityManager/Activities; interface=org.kde.ActivityManager.Activities; member=CurrentActivity
method call time=1526444336.343435 sender=:1.22 -> destination=org.kde.ActivityManager serial=279765 path=/ActivityManager/Activities; interface=org.kde.ActivityManager.Activities; member=ListActivitiesWithInformation
method call time=1526444336.343440 sender=:1.22 -> destination=org.kde.ActivityManager serial=279766 path=/ActivityManager; interface=org.kde.ActivityManager.Application; member=serviceVersion
method call time=1526444336.343445 sender=:1.37433 -> destination=org.freedesktop.DBus serial=9 path=/org/freedesktop/DBus; interface=org.freedesktop.DBus; member=AddMatch
   string "type='signal',sender='org.freedesktop.DBus',interface='org.freedesktop.DBus',member='NameOwnerChanged',arg0='org.a11y.Bus',arg1=''"
method call time=1526444336.343734 sender=:1.37433 -> destination=org.freedesktop.DBus serial=10 path=/org/freedesktop/DBus; interface=org.freedesktop.DBus; member=NameHasOwner
   string "org.a11y.Bus"
method return time=1526444336.343758 sender=org.freedesktop.DBus -> destination=:1.37433 serial=8 reply_serial=10
   boolean true
method call time=1526444336.343774 sender=:1.22 -> destination=org.freedesktop.DBus serial=279767 path=/org/freedesktop/DBus; interface=org.freedesktop.DBus; member=RemoveMatch
   string "type='signal',sender='org.kde.ActivityManager',path='/ActivityManager/Resources/Scoring',interface='org.kde.ActivityManager.ResourcesScoring',member='RecentStatsDeleted'"
method call time=1526444336.343790 sender=:1.22 -> destination=org.freedesktop.DBus serial=279768 path=/org/freedesktop/DBus; interface=org.freedesktop.DBus; member=RemoveMatch
   string "type='signal',sender='org.kde.ActivityManager',path='/ActivityManager/Resources/Scoring',interface='org.kde.ActivityManager.ResourcesScoring',member='EarlierStatsDeleted'"
method call time=1526444336.343806 sender=:1.22 -> destination=org.freedesktop.DBus serial=279769 path=/org/freedesktop/DBus; interface=org.freedesktop.DBus; member=RemoveMatch
   string "type='signal',sender='org.kde.ActivityManager',path='/ActivityManager/Resources/Scoring',interface='org.kde.ActivityManager.ResourcesScoring',member='ResourceScoreDeleted'"
method call time=1526444336.343822 sender=:1.22 -> destination=org.freedesktop.DBus serial=279770 path=/org/freedesktop/DBus; interface=org.freedesktop.DBus; member=RemoveMatch
   string "type='signal',sender='org.kde.ActivityManager',path='/ActivityManager/Resources/Scoring',interface='org.kde.ActivityManager.ResourcesScoring',member='ResourceScoreUpdated'"
method call time=1526444336.343838 sender=:1.22 -> destination=org.freedesktop.DBus serial=279771 path=/org/freedesktop/DBus; interface=org.freedesktop.DBus; member=RemoveMatch
   string "type='signal',sender='org.kde.ActivityManager',path='/ActivityManager/Resources/Linking',interface='org.kde.ActivityManager.ResourcesLinking',member='ResourceUnlinkedFromActivity'"
method call time=1526444336.343852 sender=:1.22 -> destination=org.freedesktop.DBus serial=279772 path=/org/freedesktop/DBus; interface=org.freedesktop.DBus; member=RemoveMatch
   string "type='signal',sender='org.kde.ActivityManager',path='/ActivityManager/Resources/Linking',interface='org.kde.ActivityManager.ResourcesLinking',member='ResourceLinkedToActivity'"
method call time=1526444336.344060 sender=:1.22 -> destination=org.freedesktop.DBus serial=279773 path=/org/freedesktop/DBus; interface=org.freedesktop.DBus; member=AddMatch
   string "type='signal',sender='org.kde.ActivityManager',path='/ActivityManager/Resources/Linking',interface='org.kde.ActivityManager.ResourcesLinking',member='ResourceLinkedToActivity'"
method call time=1526444336.344083 sender=:1.22 -> destination=org.freedesktop.DBus serial=279774 path=/org/freedesktop/DBus; interface=org.freedesktop.DBus; member=AddMatch
   string "type='signal',sender='org.kde.ActivityManager',path='/ActivityManager/Resources/Linking',interface='org.kde.ActivityManager.ResourcesLinking',member='ResourceUnlinkedFromActivity'"
method call time=1526444336.344099 sender=:1.22 -> destination=org.freedesktop.DBus serial=279775 path=/org/freedesktop/DBus; interface=org.freedesktop.DBus; member=AddMatch
   string "type='signal',sender='org.kde.ActivityManager',path='/ActivityManager/Resources/Scoring',interface='org.kde.ActivityManager.ResourcesScoring',member='ResourceScoreUpdated'"
method call time=1526444336.344116 sender=:1.22 -> destination=org.freedesktop.DBus serial=279776 path=/org/freedesktop/DBus; interface=org.freedesktop.DBus; member=AddMatch
   string "type='signal',sender='org.kde.ActivityManager',path='/ActivityManager/Resources/Scoring',interface='org.kde.ActivityManager.ResourcesScoring',member='ResourceScoreDeleted'"
method call time=1526444336.344133 sender=:1.22 -> destination=org.freedesktop.DBus serial=279777 path=/org/freedesktop/DBus; interface=org.freedesktop.DBus; member=AddMatch
   string "type='signal',sender='org.kde.ActivityManager',path='/ActivityManager/Resources/Scoring',interface='org.kde.ActivityManager.ResourcesScoring',member='RecentStatsDeleted'"
method call time=1526444336.344149 sender=:1.22 -> destination=org.freedesktop.DBus serial=279778 path=/org/freedesktop/DBus; interface=org.freedesktop.DBus; member=AddMatch
   string "type='signal',sender='org.kde.ActivityManager',path='/ActivityManager/Resources/Scoring',interface='org.kde.ActivityManager.ResourcesScoring',member='EarlierStatsDeleted'"
method call time=1526444336.344178 sender=:1.37433 -> destination=org.freedesktop.DBus serial=11 path=/org/freedesktop/DBus; interface=org.freedesktop.DBus; member=AddMatch
   string "type='signal',sender='org.freedesktop.DBus',interface='org.freedesktop.DBus',member='NameOwnerChanged',arg0='org.a11y.Bus'"
method call time=1526444336.344253 sender=:1.37433 -> destination=org.freedesktop.DBus serial=12 path=/org/freedesktop/DBus; interface=org.freedesktop.DBus; member=GetNameOwner
   string "org.a11y.Bus"


Here is the output of qdbus in case this is helpful

Code: Select all

:1.101
 org.freedesktop.Akonadi.Agent.akonadi_imap_resource_2
 org.freedesktop.Akonadi.Resource.akonadi_imap_resource_2
:1.102
 org.freedesktop.Akonadi.Agent.akonadi_sendlater_agent
 org.freedesktop.Akonadi.SendLaterAgent
:1.103
 org.freedesktop.Akonadi.Agent.akonadi_archivemail_agent
 org.freedesktop.Akonadi.ArchiveMailAgent
:1.104
:1.105
:1.106
:1.109
 org.freedesktop.Akonadi.Agent.akonadi_mailfilter_agent
 org.freedesktop.Akonadi.MailFilterAgent
:1.11
 org.kde.kglobalaccel
:1.110
:1.117
:1.120
:1.121
 org.kde.JobViewServer
 org.kde.kuiserver
:1.122
:1.128
:1.139
 org.kde.kiod5
 org.kde.kioexecd
 org.kde.kpasswdserver
 org.kde.kssld5
:1.14
 org.freedesktop.ScreenSaver
 org.kde.ksmserver
 org.kde.screensaver
:1.147
 org.kde.kdeconnect
 org.kde.kdeconnectd
:1.15944
 org.kde.runners.baloo
:1.15947
:1.16
 org.kde.baloo
:1.18
 org.kde.KScreen
:1.18674
 org.kde.kaddressbook
 org.kde.kmail
 org.kde.kmail2
 org.kde.kontact
 org.kde.korganizer
 org.kde.pim.TransportManager
:1.18694
:1.18695
:1.18699
:1.18703
:1.18728
:1.18997
:1.19
 org.kde.kwalletd
 org.kde.kwalletd5
:1.2
 org.kde.klauncher5
:1.20
 org.kde.KWin
:1.21
 org.kde.krunner
:1.21246
 org.kde.konsole-26127
:1.22
 com.canonical.Unity
 org.freedesktop.Notifications
 org.kde.StatusNotifierHost-1966
 org.kde.klipper
 org.kde.plasmashell
:1.23
:1.25
 org.a11y.Bus
:1.25479
:1.25484
:1.25485
:1.26
 org.PulseAudio1
 org.pulseaudio.Server
:1.2772
 org.mozilla.firefox.c2VjdXJl
:1.2774
:1.28
 org.freedesktop.Tracker1.Miner.Extract
:1.284
 org.kio5.kio_http_cache_cleaner
:1.29
 org.freedesktop.Tracker1.Miner.Files
 org.freedesktop.Tracker1.Miner.Files.Index
:1.30
:1.31
 org.gtk.vfs.Daemon
:1.34
 local.org_kde_powerdevil
 org.freedesktop.PowerManagement
 org.freedesktop.PowerManagement.Inhibit
 org.kde.Solid.PowerManagement
 org.kde.Solid.PowerManagement.PolicyAgent
:1.35
 org.kde.polkit-kde-authentication-agent-1
:1.36
 org.kde.yakuake
:1.37
 org.freedesktop.Tracker1.Miner.Applications
:1.38
 org.gtk.vfs.UDisks2VolumeMonitor
:1.39
 org.freedesktop.Tracker1
:1.4
 org.kde.StatusNotifierWatcher
 org.kde.kappmenu
 org.kde.kcookiejar5
 org.kde.kded5
 org.kde.keyboard
 org.kde.plasmanetworkmanagement
:1.40
:1.41
 org.freedesktop.Tracker1.Miner.Userguides
:1.42
:1.43
 org.kde.korgac
:1.45
 org.gnome.GConf
:1.45836
:1.46
:1.48
:1.49
:1.5
 org.kde.kaccess
:1.50
 org.freedesktop.Akonadi.Control
 org.freedesktop.Akonadi.Control.lock
:1.51
 org.freedesktop.Akonadi
:1.56
 org.gtk.vfs.Metadata
:1.58
 org.bluez.obex
:1.66
:1.67
:1.67487
:1.67489
:1.67490
:1.68
 org.freedesktop.Akonadi.Janitor
:1.70
 org.freedesktop.Akonadi.Agent.akonadi_birthdays_resource
 org.freedesktop.Akonadi.Resource.akonadi_birthdays_resource
:1.72
:1.73
 org.freedesktop.Akonadi.Agent.akonadi_ical_resource_0
 org.freedesktop.Akonadi.Resource.akonadi_ical_resource_0
:1.74
:1.75
 org.freedesktop.Akonadi.Agent.akonadi_akonotes_resource_0
 org.freedesktop.Akonadi.Resource.akonadi_akonotes_resource_0
:1.76
 org.freedesktop.Akonadi.Agent.akonadi_contacts_resource_0
 org.freedesktop.Akonadi.Resource.akonadi_contacts_resource_0
:1.77
:1.78
:1.80
 org.freedesktop.Akonadi.Agent.akonadi_migration_agent
:1.81
 org.freedesktop.Akonadi.Agent.akonadi_maildispatcher_agent
 org.freedesktop.Akonadi.MailDispatcherAgent
:1.82
 org.freedesktop.Akonadi.Agent.akonadi_davgroupware_resource_2
 org.freedesktop.Akonadi.Resource.akonadi_davgroupware_resource_2
:1.83
:1.85
:1.86
 org.freedesktop.Akonadi.Agent.akonadi_davgroupware_resource_3
 org.freedesktop.Akonadi.Resource.akonadi_davgroupware_resource_3
:1.87
 org.freedesktop.Akonadi.Agent.akonadi_maildir_resource_0
 org.freedesktop.Akonadi.Resource.akonadi_maildir_resource_0
:1.88
:1.89
 org.freedesktop.Akonadi.Agent.akonadi_indexing_agent
:1.9
 ca.desrt.dconf
:1.90
 org.freedesktop.Akonadi.Agent.akonadi_followupreminder_agent
 org.freedesktop.Akonadi.FollowUpReminder
:1.91
:1.92
:1.93
:1.94
 org.freedesktop.Akonadi.Agent.akonadi_newmailnotifier_agent
 org.freedesktop.Akonadi.NewMailNotifierAgent
:1.95
:1.96
:1.98
 org.freedesktop.Akonadi.Agent.akonadi_notes_agent
 org.freedesktop.Akonadi.NotesAgent
:1.99
org.freedesktop.DBus


But this is where my knowledge of DBus and debugging end, and I'm stuck as to where to go next. I have tried deleting `~/.config/plasmashellrc` and `~/.config/plasma-org.kde.plasma.desktop-appletsrc` and rebooting in case any of my plasmoids where causing the problem but this didn't help.

I have never made use of the "activities" feature of plasma, so only a single default activity exists. However, suspiciously if I use the activity pager shortcut (shift+meta+tab on my system), the "default" activity thumbnail keeps sliding in and out of view very quickly, perhaps supporting the view that something fishy is going on with the activities.

I'd be really grateful for any advice on:
- Further debugging to figure out what is sending all these messages
- Whether there are better places for me to get help or submit formal bug requests

Thanks in advance!

I never really got to the bottom of what happened here but further digging suggested that the sqlite database that kactivitymanagerd uses to store details of different activities somehow got corrupted. I'm at a loss to explain how this happened.

I appear to have fixed the issue by deleted the following files and restarting plasmashell:

- `~/.local/share/kactivitymanagerd/resources/database*`
- `~/.config/kactivitymanagerd*`

Thanks for documenting this, cbridge. It fixed my problem. I will list my "symptoms" for the benefit of others searching. While the cause remains unknown in my mind, I believe it started after I edited a start menu entry.

My recent apps and favorites disappeared and would not repopulate. While bringing up the activity manager, either from right clicking the desktop or from settings, things would flash or cycle. I also noticed runaway cpu usage related to kactivitymanagerd.