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[Brian Murray <1946003@xxxxxxxxxxxxxxxxxx>]

** Also affects: cloud-init (Ubuntu)
   Importance: Undecided
       Status: New

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https://bugs.launchpad.net/bugs/1946003

Title:
  hotplug causing cloud-init to spike CPU usage

Status in cloud-init:
  Triaged
Status in cloud-init package in Ubuntu:
  New

Bug description:
  In 21.3, we added udev rules to enable the cloud-init hotplug
  functionality. If a new device is detected, we call into cloud-init to
  see if hotplug is supported/enabled, then proceed accordingly based on
  the results. There are cloud users that are creating and disposing
  docker containers at a very high rate. This causes many virtual
  ethernet adapters to be created and disposed. This is triggering
  cloud-init events at a high volume, consuming significant CPU. Even
  with the hotplug functionality being disabled, the act of checking if
  hotplug is enabled is causing the spikes in CPU.

  The path taken is:
  https://github.com/canonical/cloud-init/blob/main/udev/10-cloud-init-hook-hotplug.rules
  to
  https://github.com/canonical/cloud-init/blob/main/tools/hook-hotplug
  to
  https://github.com/canonical/cloud-init/blob/main/cloudinit/cmd/devel/hotplug_hook.py#L158


  For more context, see IRC conversations from 10/1/2021 and 10/4/2021:
  https://irclogs.ubuntu.com/2021/10/01/%23cloud-init.html
  https://irclogs.ubuntu.com/2021/10/04/%23cloud-init.html

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