[Bug 1518430] Re: liberty: ~busy loop on epoll_wait being called with zero timeout

[Brian Murray]

Hello JuanJo, or anyone else affected,

Accepted python-oslo.messaging into yakkety-proposed. The package will
build now and be available at https://launchpad.net/ubuntu/+source
/python-oslo.messaging/5.10.0-0ubuntu2 in a few hours, and then in the
-proposed repository.

Please help us by testing this new package.  See
https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to
enable and use -proposed.  Your feedback will aid us getting this update
out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug,
mentioning the version of the package you tested, and change the tag
from verification-needed to verification-done. If it does not fix the
bug for you, please add a comment stating that, and change the tag to
verification-failed.  In either case, details of your testing will help
us make a better decision.

Further information regarding the verification process can be found at
https://wiki.ubuntu.com/QATeam/PerformingSRUVerification .  Thank you in
advance!

** Changed in: python-oslo.messaging (Ubuntu Yakkety)
       Status: New => Fix Committed

** Tags added: verification-needed

** Changed in: python-oslo.messaging (Ubuntu Xenial)
       Status: New => Fix Committed

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https://bugs.launchpad.net/bugs/1518430

Title:
  liberty: ~busy loop on epoll_wait being called with zero timeout

Status in Ubuntu Cloud Archive:
  Fix Committed
Status in Ubuntu Cloud Archive kilo series:
  Fix Committed
Status in Ubuntu Cloud Archive liberty series:
  Fix Committed
Status in Ubuntu Cloud Archive mitaka series:
  Fix Committed
Status in Ubuntu Cloud Archive newton series:
  Fix Committed
Status in oslo.messaging:
  Fix Released
Status in python-oslo.messaging package in Ubuntu:
  Fix Released
Status in python-oslo.messaging source package in Xenial:
  Fix Committed
Status in python-oslo.messaging source package in Yakkety:
  Fix Committed
Status in python-oslo.messaging source package in Zesty:
  Fix Released

Bug description:
  Context: openstack juju/maas deploy using 1510 charms release
  on trusty, with:
    openstack-origin: "cloud:trusty-liberty"
    source: "cloud:trusty-updates/liberty

  * Several openstack nova- and neutron- services, at least:
  nova-compute, neutron-server, nova-conductor,
  neutron-openvswitch-agent,neutron-vpn-agent
  show almost busy looping on epoll_wait() calls, with zero timeout set
  most frequently.
  - nova-compute (chose it b/cos single proc'd) strace and ltrace captures:
    http://paste.ubuntu.com/13371248/ (ltrace, strace)

  As comparison, this is how it looks on a kilo deploy:
  - http://paste.ubuntu.com/13371635/

  * 'top' sample from a nova-cloud-controller unit from
     this completely idle stack:
    http://paste.ubuntu.com/13371809/

  FYI *not* seeing this behavior on keystone, glance, cinder,
  ceilometer-api.

  As this issue is present on several components, it likely comes
  from common libraries (oslo concurrency?), fyi filed the bug to
  nova itself as a starting point for debugging.

  Note: The description in the following bug gives a good overview of
  the issue and points to a possible fix for oslo.messaging:
  https://bugs.launchpad.net/mos/+bug/1380220

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