Performance - high cpu load after a while

[dobin]

Describe the bug

It appears that Fibratus 2.4.0 is using 100% of a core in a idle 2-core VM after running for a while.

Windows:

Proxmox:

Proxmox VM:

How to reproduce it

• Install fibratus on windows 11 vm
• Let it run for a day or two

Expected behavior

A low cpu utilisation when the VM is idling.

After a reboot:

Environment

[rabbitstack]

Hi @dobin. I appreciate raising the bug. I have a wild guess that excessive CPU utilization could be triggered by a tight loop happening under unpredictable conditions.

Can I kindly ask for CPU profiles?

You'll need Go 1.23.x installed on the machine. Then run the following command when Fibratus is stuck in a high CPU consumption state:

go tool pprof http://localhost:8482/debug/pprof/profile

After the command completes, you'll land into pprof CLI. Then type proto and attach the pb.tgz file.

Additionally, could you also get the following by opening the URL in the browser?

• expvars: http://localhost:8482/debug/vars
• goroutine summary: http://localhost:8482/debug/pprof/goroutine?debug=1

Lastly, any warning/error logs, or if you notice excessive log messages being written.

Thanks

P.S. I'm currently sick, so I'll not be able to look into it immediately.

[dobin]

profile001.pb.gz
debug-vars.json
fibratus.log
goroutine.txt

System Boot Time: 20.01.2026, 11:05:52

[rabbitstack]

Thanks for providing these files. I narrowed it down to an infinite loop which also causes a deadlock. I'll correct this defect in the next version.