Created attachment 103579 [details] htop screenshot of krunner cpu usage My system was acting sluggish today, so I opened htop to discover that krunner had pegged all 4 of my cores at 100% usage! It seemed to have spawned 4 subprocesses, each of which was using 100% of a core. I restarted my PC and my CPU usage was normal again. I managed to reproduce the bug as follows (with opening krunner by pressing alt+space): * Start okular through krunner: CPU usage normal * Search for a PDF through krunner and open it in the previous okular instance: one core starts running at 100% * Search and open a second PDF: a second core starts running at 100% * Try opening a few more PDFs: no change in CPU usage, still 2 cores pegged at 100% * Open gwenview through krunner: no change * Try opening another PDF: a third core starts running at 100% * Open spectacle through krunner: a fourth core starts running at 100% So the bug is reproducible after using krunner enough times, but not every usage results in another subprocess being spawned using 100% CPU. I've attached a screenshot of htop, as well as the open file handles for both the parent krunner process and one of the children using 100% CPU. Bug 364268 also seems to describe this problem, however I can confirm that the bug does not only happen when opening OpenGL apps. System specs: Kernel version: 4.8.13-1-ARCH plasma version: 5.8.5 kf5 version: 5.30.0 kapps version: 16.12.1 CPU: i5-4690K GPU: Nvidia GTX 970 with proprietary driver, version 375.26
Created attachment 103580 [details] Open file handles for krunner parent and child It's strange how krunner has open file handles to /dev/nvidia0 and the like... I suppose krunner somehow uses GPU acceleration?
Yes, krunner uses QtQuick, which uses OpenGL GPU for rendering.
I seem to be unable to reproduce this bug after updating to Plasma 5.9.1. There isn't much in the changelog related to krunner, but perhaps the bug was elsewhere.
I still haven't been able to reproduce this over the past week, and can't reproduce it now with Plasma 5.9.2, so I'm going to close this.