[PLASMA 5] Delay when using search in application launcher

[kiekerjan]

I often use the search function of the application launcher to quickly get to the program I want to use. Somewhere during the last year I ran into the following issue. When I start searching, the first character I type is displayed and then the whole desktop freezes and becomes unresponsive. This takes a few seconds after which the desktop becomes responsive once more and the launcher search is completed. I already ran into this with kubuntu 19.04 and it is still present in kubuntu 19.10. I don't see updates in /var/log or in ~/.xsession-errors.
Does anyone have any troubleshooting ideas?

[jlittle]

I suspect baloo... one of the "runners" that "krunner" starts looks up stuff in the baloo file index.

• What is the size of ~/.local/share/baloo/index?
• Do you have "enable file search" ticked in system settings-> search -> file search?
  and if so, is "also index file content" ticked?
• How many files and how many data do have that the file indexer would be looking in?

Baloo has given trouble for many. It's predecessor (nepomuk) gave so much trouble the idea, semantic search, was restarted. I've recently disabled it (again) because the index was 0.5 GB, indexing only about 6 GB of data, mostly music and photos, and that with "also index file content" turned off. I dug in to what I could find out about baloo and I don't like some of their design decisions; one of them stops me finding out what it's doing, so I can't diagnose problems. Also, the index file can get screwed up, causing it to bloat.

If the index is large, and the runner reads a lot of it, your system might be hitting i/o starvation, which would give the symptoms you describe. Or conceivably the runner might spike memory usage causing swapping, though that should be a problem from decades ago.

[kiekerjan]

Thanks for your quick reply and apologies for my later answer.
~/.local/share/baloo/index is about 4.5 megabytes:

~/.local/share/baloo$ ll
total 2033
drwxrwxr-x   7 jan jan       9 Jan  3 11:25 ./
drwxr-xr-x 105 jan jan     115 Jan 22 10:44 ../
drwxrwxr-x   2 jan jan      16 Jul  2  2019 calendars/
drwxrwxr-x   2 jan jan       7 Jun 30  2019 contacts/
drwxrwxr-x   2 jan jan      10 Dec  8  2017 email/
drwxrwxr-x   2 jan jan      10 Dec  8  2017 emailContacts/
-rw-rw-r--   1 jan jan 4677632 Jan  3 11:25 index
-rw-rw-r--   1 jan jan    8192 Jan 23 19:26 index-lock
drwxrwxr-x   2 jan jan      10 Nov 21  2017 notes/

Both search options are disable, so it doesn't seem to be baloo.

[kiekerjan]

Found another clue: when I add XDG_CACHE_HOME=/tmp; export XDG_CACHE_HOME; to my .profile, the delay is completely gone.