I was logging into KDE 4.9.1 (installed three days ago). Now, after logging in I noticed that the following processes have 100% CPU usage: PID USER PRI NI VIRT RES SHR S CPU% MEM% TIME+ Command 3270 aki 20 0 781M 52124 28032 R 100. 0.5 16:58.56 kdeinit4: krunner [kdeinit] 3156 aki 20 0 330M 18368 13400 R 99.0 0.2 16:57.77 /usr/bin/kactivitymanagerd 3366 aki 20 0 583M 45436 24912 R 99.0 0.4 16:58.15 kdeinit4: dolphin [kdeinit] -session 10157fbe1ea00013471870310 3528 aki 20 0 334M 22132 17624 R 99.0 0.2 14:08.67 /usr/bin/akonadi_nepomuk_feeder --identifier akonadi_nepomuk_feeder krunner, kactivitymanagerd, dolphin and akonadi_nepomuk_feeder. I created a backtrace with GDB of all, you can inspect them. Krunner was already in zombie state at the time the backtraces were made. Maybe this could be useful also, from qdbus-viewer: org.kde.NepomukServer: isFileIndexerEnabled: false isNepomukEnabled: true runningServices: {"nepomukstorage"} isServiceAutostarted (nepomukstorage): true isServiceRunning (nepomukstorage): true isServiceInitialized (nepomukstorage): false NepomukStorage: usedSopranoBackend: virtuosobackend The org.kde.akonadi_nepomuk_feeder_3528 doesn't respond (time out from D-Bus request). Command: qdbus org.kde.nepomuk.services.nepomukqueryservice Response: Service 'org.kde.nepomuk.services.nepomukqueryservice' does not exist. Reproducible: Didn't try
Created attachment 73773 [details] Backtrace of akonadi_nepomuk_feeder
Created attachment 73774 [details] Backtrace of kactivitymanagerd.txt
Created attachment 73775 [details] Bactrace of Dolphin (kdeinit4)
I also noticed this problem on KDE 4.9.1 on Arch Linux. Sometimes, after login the CPU usage goes to 100% for three processes (using three cores). These processes are kdeinit (krunner), akonadi_nepomuk_feeder and kactivitymanagerd. I have no idea how to reproduce this though, it has only occurred three times or so now.
After a new upgrade to 4.9.3 (interesting that this bug appears after updates) I encountered this issue again. I created the following files. If you want to debug them, simply there's no better solution than these files. 1.) Callgrind graph why the plasma-desktop never loaded while the others were on 100% CPU usage: http://www.morrohun.hu/temp/plasma-desktop.tar.xz 2.) Full core file from akonadi_nepomuk_feeder and kactivitymanagerd while they used 100% CPU: http://www.morrohun.hu/temp/akonadi-kactivity-core.tar.xz 3.) Full core file from Dolphin in the same time: http://www.morrohun.hu/temp/dolphin-core.tar.xz If you need, I can upload a KMail core also.
The Nepomuk project is no longer maintained in KDE since 4.13. For email indexing, Baloo provided an Akonadi resource to index emails, contacts and events. Tags are now maintained by Akonadi itself.