Often (enough) something completely dumb happens, like some browser tab in the background spins an endless CSS animation, and CPU does pointless work for hours, days, weeks even.
I’m finding zero integrated Gnome DE tools to monitor for this. Current workaround is to check htop when it seems laptop fans spin too loud, or battery drains too quick. It’s up to the user to notice on some set of uncertain heuristics.
I’ve always thought detecting that type of stuff is what we have computers for in the first place.
Am I missing anything about available tooling, should something be developed, or how do you do it?
I have it, and it’s a tool with a different purpose. Battery drain by itself could also be a result of actual useful work.
What I’m looking for is some integrated periodic measurement thing, that is able to post a notification based on some criteria, draw some simple chart in icon tray, or something.
GNOME System Monitor will show you the current CPU and memory use, as well list processes. It’s basically a GUI version of htop, with a bit more information. You could, conceivably, add a notification mechanism to the System Monitor to notify you that there’s a process consuming one or more of your cores, but how are you going to distinguish a runaway process from, for instance, your compiler building an application, or a video editing suite rendering a video, or a web browser showing you a Slack channel?
You are not asking for an application, though:
If you want a monitoring tool that always sits in a visible area of your desktop, then you’ll have to look for GNOME Shell extensions, like: