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[Bug 1705340] [NEW] Unable to boot large instances due to prlimit setting

 

Public bug reported:

I recently had the need to migrate some instances from an old KIlo
cluster to a new Ocata one. Some of the snapshots were 120GB or more
(terrible I know). Due to a prlimit limitation of cpu=8, these instances
are unable to spawn.

Changing nova/virt/images.py line 42 from

    cpu_time=8,

to

    cpu_time=16,

allowed the instances to boot properly.

This was implemented at 2 seconds and later changed to 8 seconds as part of:
https://review.openstack.org/gitweb?p=openstack/nova.git;a=commitdiff;h=068d851561addfefb2b812d91dc2011077cb6e1d

Here's my qemu-img info process taking more than 8 seconds:
9ddeea47df894145.part execute
/usr/lib/python2.7/site-packages/oslo_concurrency/processutils.py:355
2017-07-19 19:47:42.849 7 DEBUG oslo_concurrency.processutils
[req-7ed3314d-1c11-4dd8-b612-f8d9c022417f
ff236d57a57dd42cb5811c998e30fca1a76233873b9f08330f725fb639c8b025
9776d48734a24c23a4aef51cb78cc269 - - -] CMD "/usr/bin/python2 -m
oslo_concurrency.prlimit --as=1073741824 --cpu=16 -- env LC_ALL=C
LANG=C qemu-img info
/var/lib/nova/instances/_base/41ebff725eab55d368f97bc79ddeea47df894145.part"
returned: 0 in 8.639s execute
/usr/lib/python2.7/site-packages/oslo_concurrency/processutils.py:385

Would it be possible to increase the default setting, or better yet make
it a configuration variable so we don't have to keep chasing it?

** Affects: nova
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/1705340

Title:
  Unable to boot large instances due to prlimit setting

Status in OpenStack Compute (nova):
  New

Bug description:
  I recently had the need to migrate some instances from an old KIlo
  cluster to a new Ocata one. Some of the snapshots were 120GB or more
  (terrible I know). Due to a prlimit limitation of cpu=8, these
  instances are unable to spawn.

  Changing nova/virt/images.py line 42 from

      cpu_time=8,

  to

      cpu_time=16,

  allowed the instances to boot properly.

  This was implemented at 2 seconds and later changed to 8 seconds as part of:
  https://review.openstack.org/gitweb?p=openstack/nova.git;a=commitdiff;h=068d851561addfefb2b812d91dc2011077cb6e1d

  Here's my qemu-img info process taking more than 8 seconds:
  9ddeea47df894145.part execute
  /usr/lib/python2.7/site-packages/oslo_concurrency/processutils.py:355
  2017-07-19 19:47:42.849 7 DEBUG oslo_concurrency.processutils
  [req-7ed3314d-1c11-4dd8-b612-f8d9c022417f
  ff236d57a57dd42cb5811c998e30fca1a76233873b9f08330f725fb639c8b025
  9776d48734a24c23a4aef51cb78cc269 - - -] CMD "/usr/bin/python2 -m
  oslo_concurrency.prlimit --as=1073741824 --cpu=16 -- env LC_ALL=C
  LANG=C qemu-img info
  /var/lib/nova/instances/_base/41ebff725eab55d368f97bc79ddeea47df894145.part"
  returned: 0 in 8.639s execute
  /usr/lib/python2.7/site-packages/oslo_concurrency/processutils.py:385

  Would it be possible to increase the default setting, or better yet
  make it a configuration variable so we don't have to keep chasing it?

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