oomparser - new constructor to support streaming of new/current OOM events only.

[jesseward]

Summary

This adds a new constructor NewFromNow that moves the /dev/kmsg reader offset to the end of the queue. Allowing the user to ignore OOM events that occurred prior to the creation of the OomParser object.

Examples

Create stream using New (default behaviour)

Returns all available OOM events in the kmsg buffer. This is the default behaviour and is not changed.

$ sudo go run oomexample/main.go 
I0727 20:31:50.742685 1989715 main.go:48] Reading the buffer. Output is &{393038 stress-ng-vm 2025-07-25 23:11:27.182087673 +0000 UTC m=-163223.536149722 /system.slice/docker-4876bd1d7f860bacc8df1c342f058bb861c41a328a1cce0b753eae6f0849b241.scope/kubelet.slice/kubelet-kubepods.slice/kubelet-kubepods-burstable.slice/kubelet-kubepods-burstable-podd993a249_6fb5_48dc_90fe_5c176fa43a7f.slice/cri-containerd-85a888cadb58adab390959abaa0db3996a9997193d137ed321dcf0e0b56c680b.scope /system.slice/docker-4876bd1d7f860bacc8df1c342f058bb861c41a328a1cce0b753eae6f0849b241.scope/kubelet.slice/kubelet-kubepods.slice/kubelet-kubepods-burstable.slice/kubelet-kubepods-burstable-podd993a249_6fb5_48dc_90fe_5c176fa43a7f.slice CONSTRAINT_MEMCG}
I0727 20:31:50.743393 1989715 main.go:48] Reading the buffer. Output is &{393053 stress-ng-vm 2025-07-25 23:11:27.910033673 +0000 UTC m=-163222.808203722 /system.slice/docker-4876bd1d7f860bacc8df1c342f058bb861c41a328a1cce0b753eae6f0849b241.scope/kubelet.slice/kubelet-kubepods.slice/kubelet-kubepods-burstable.slice/kubelet-kubepods-burstable-podd993a249_6fb5_48dc_90fe_5c176fa43a7f.slice/cri-containerd-85a888cadb58adab390959abaa0db3996a9997193d137ed321dcf0e0b56c680b.scope /system.slice/docker-4876bd1d7f860bacc8df1c342f058bb861c41a328a1cce0b753eae6f0849b241.scope/kubelet.slice/kubelet-kubepods.slice/kubelet-kubepods-burstable.slice/kubelet-kubepods-burstable-podd993a249_6fb5_48dc_90fe_5c176fa43a7f.slice CONSTRAINT_MEMCG}
I0727 20:31:50.744026 1989715 main.go:48] Reading the buffer. Output is &{393056 stress-ng-vm 2025-07-25 23:11:28.623308673 +0000 UTC m=-163222.094928722 /system.slice/docker-4876bd1d7f860bacc8df1c342f058bb861c41a328a1cce0b753eae6f0849b241.scope/kubelet.slice/kubelet-kubepods.slice/kubelet-kubepods-burstable.slice/kubelet-kubepods-burstable-podd993a249_6fb5_48dc_90fe_5c176fa43a7f.slice/cri-containerd-85a888cadb58adab390959abaa0db3996a9997193d137ed321dcf0e0b56c680b.scope /system.slice/docker-4876bd1d7f860bacc8df1c342f058bb861c41a328a1cce0b753eae6f0849b241.scope/kubelet.slice/kubelet-kubepods.slice/kubelet-kubepods-burstable.slice/kubelet-kubepods-burstable-podd993a249_6fb5_48dc_90fe_5c176fa43a7f.slice CONSTRAINT_MEMCG}

Create stream using NewFromNow

When launched, old OOM events are ignored and net new events are reported (as seen at I0727 20:05:50.120013)

$ sudo go run oomexample/main.go -ignore_old
I0727 20:05:50.120013 1966714 main.go:48] Reading the buffer. Output is &{1967893 awk 2025-07-27 20:05:46.893944354 +0000 UTC m=+51.345637220 /system.slice/docker-8e95fa377f7d8be8aa72ddb5cf50b76111d3d6c4d89f2048c597a7b2fb6970b0.scope/kubelet.slice/kubelet-kubepods.slice/kubelet-kubepods-burstable.slice/kubelet-kubepods-burstable-pod0997ebc7_7b70_4a20_9a87_c7eca4342fc9.slice/cri-containerd-cb0c72b671bad34ce5255356006d91fdd704506e8da2b51887168f29815ef9ac.scope /system.slice/docker-8e95fa377f7d8be8aa72ddb5cf50b76111d3d6c4d89f2048c597a7b2fb6970b0.scope/kubelet.slice/kubelet-kubepods.slice/kubelet-kubepods-burstable.slice/kubelet-kubepods-burstable-pod0997ebc7_7b70_4a20_9a87_c7eca4342fc9.slice CONSTRAINT_MEMCG}

Related

• Resolves cadvisor/utils/oomparser - Add constructor to (optionally) allow streaming of current+new OOMs only. #3715