Skip to content

macos – Random system freeze with kernel_task using 12.5% CPU, how to diagnose?

  • by
Spread the love

For a couple days I’ve been having random hangs from macOS. It seems to happen quite often when opening PDF files stored in Zotero with an external reader (PDF Expert) but it is not limited to that—which makes me think it could be a hard disk problem (?)

When it happens, the whole system is still responsive (can move the mouse, click or type things, etc.), but several things seem to halt: if I just clicked on a web page link, the new page won’t load (as if network was disconnected), Finder seems to hang (mouse becomes a spinning wheel when switching to it), my iStat menu showing active processes will freeze, or if I’m opening a file it’s gonna hang as well.

Then all of a sudden, after 10-30 seconds, everything will un-freeze, web pages will load, files will open, etc. This seems pretty random, or at least, I have not been able to reproduce the behavior reliably.

I’m somewhat technical but not an expert in OS kernels, but it seems as if a kernel thread was stuck or something (?) which blocks all the other requests from being processed. The kernel_task process uses exactly 1 core (12.5% CPU) during the whole time the system hangs.

The big problem here is that I have absolutely no idea how to debug this, if it’s a software or a hardware issue, or anything. I’ve taken a look at the Console and the various logs and I don’t see anything too obvious, but I’m not technical enough in macOS’s internal workings to be able to really discern between normal or problematic entries. I have suspected CPU temperature issues (seems to be frequent with this process using up CPU) but it also happens while the machine is mostly idle, and I’ve taken a look at temperature readings and they don’t seem too unusual.

I’m running the latest Ventura available on my machine, 13.1 (22C65). The computer is a 13-inch, 2020, macbook pro.

Where should I start?

Leave a Reply

Your email address will not be published. Required fields are marked *