Error:

    "main-loop: WARNING: I/O thread spun for 1000 iterations"

Error origin: https://github.com/qemu/qemu/blob/master/main-loop.c#L224

Reproducer
----------

(1) Have a DevStack setup running:

           $ cd /path/to/tempest

(2) Enable these libvirt log filters:

  log_filters="1:libvirt 1:qemu 1:conf 1:security 3:event 3:json 3:file 3:object 1:util 1:qemu_monitor"
  log_outputs="1:file:/var/log/libvirt/libvirtd.log"

  Restart libvirtd.

(3) Invoke this test:

        https://github.com/openstack/tempest/blob/master/tempest/api/compute/servers/test_server_rescue_negative.py#L85

        $ tox -eall ServerRescueNegativeTestJSON
    (Or)
        $ tox -eall test_rescued_vm_detach_volume

(4) Analyze the libvirtd.log file

Manual reproducer
-----------------

  - Boot an instance:
    
      $ nova boot --flavor 1 --key_name oskey1 --image \
        cirros-0.3.2-x86_64-uec vm1
        
  - Pause it: 
    
      $ nova pause vm1

  - Try a rescue:
    
      $ nova rescue


Notes after discussion w/ Nikola
--------------------------------

[It tries to prove that api will reject a rescue request on a paused
server. The only thing that will hit compute node on that test should be
the pause as the rescue will get rejected by the API service.]


Related bugs: 

  - https://bugs.launchpad.net/nova/+bug/1353939 -- Rescue fails with
    'Failed to terminate process: Device or resource busy' in the n-cpu
    log

  - https://bugs.launchpad.net/nova/+bug/1373513 -- Lvm hang during
    tempest tests

    (mriedem on #openstack-nova: I always lumped that bug in with the
    other gate bugs related to lvm intermittently getting locked up for
    2 minutes)