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Fixing a kubelet memory leak in Kubernetes 1.36

35 points by compumike ago | 7 comments

compumike |next [-]

Author here! If you're running a Kubernetes cluster, I recommend you check `kubectl version` and see if you're running "Server Version: v1.36.[0,1,2]". If so, you may want to use the one-liner at the end of the article to check your "process_resident_memory_bytes" on each node, and consider restarting kubelet as a temporary workaround to tame the memory leak until v1.36.3 is released.

__turbobrew__ |next |previous [-]

A good reason to health check the kubelet process and restart it when the checks fail.

compumike |root |parent [-]

What kind of health checks? In my case, the kubelet process was staying alive and responsive to queries, I believe due to:

  # cat /proc/$(pgrep kubelet)/oom_score_adj
  -999
  
  (from OOMScoreAdjust=-999 in /etc/systemd/system/kubelet.service)
With this score, the Linux OOM killer wouldn't touch it, but any of my Pods were fair game.

rirze |next |previous [-]

Very cool. It's often daunting to contribute to such a well-established and recognizable project, but this is exactly how it should work.

CamouflagedKiwi |next |previous [-]

Nice find.

Can't help but feel this is one of the subtle traps hidden beneath the advice that contexts aren't supposed to be stored. I know it's not always that easy, of course.

compumike |root |parent [-]

Thanks. I know there's a `go vet` tool that's run as part of Kubernetes CI, and one of its checks is:

  lostcancel: check cancel func returned by context.WithCancel is called
I'm not 100% sure why `go vet` didn't catch this issue, but storing the cancelFn in the struct is probably part of the reason. Any Go experts know if that's the case?

fsuts |previous [-]

Not all heroes wear capes! Well done