Created attachment 105347 [details] GDB backtrace Version: 5.9.5 (latest on Arch Linux x86_64). After my PC is up and running for a few (4~5+) hours, kscreenlocker_greet takes a full minute until it is responsive and reacts to keyboard or mouse input. And yes, I've actually timed it; the standard deviation was +/- 2 seconds. During that minute, CPU usages spikes to 100% and reserved memory (in top) eventually exceeds 500 MB. I've also noticed memory usage increases every 5 seconds or so, and by 10-20 MB increments. When the program's responsive again, CPU returns to normal, while memory usage is reduced to around 400 MB. The problem happens independent of how kscreenlocker_greet is invoked: by locking the screen; letting it happen automatically because of inactivity; or even by running it from the terminal directly (with or without the '--testing' option; it doesn't matter). Sending a HUP signal to the process or using loginctl to unlock the session is a workaround, but very annoying. GDB backtrace (attached) indicates the program is stuck waiting for... something. Since the time kscreenlocker_greet is unresponsive is so precise, I suspect it's a timeout expiring which causes it to be responsive again.
Unfortunately the backtrace is lacking debug symbols. If you are able to reproduce please install the debug packages and attach a new backtrace. Without the debug symbols we do not see where it crashes.
Created attachment 105362 [details] GDB backtrace (with symbols) Ah, I recompiled kscreenlocker with the debug symbols, but forgot about Qt :)
Thanks for the update; it looks like a Qt issue.
@Christoph Feck So should I go and file a bug on the Qt tracker? Right now it happens only with kscreenlocker though. I'll keep an eye open, see if any other Qt programs show similar behavior.
It is related to QQuickWindow (from QtQuick), which is only used by a minority of applications.
Is this now resolved upstream?
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I haven't had the problem for a while now, so I suppose it's been fixed.