Comment 3 for bug 1258179

Reviewed: https://review.openstack.org/60259
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=933603ed8523493d0693f02f62fef6d427de421f
Submitter: Jenkins
Branch: master

commit 933603ed8523493d0693f02f62fef6d427de421f
Author: Gary Kotton <email address hidden>
Date: Thu Dec 5 06:50:06 2013 -0800

    VMware: optimize instance reference access

    Fix bug causing nova-compute CPU to spike to 100%.

    When there are hundreds of VMs running each time a VM is referenced
    all of the VMs in the system will be read by nova-compute and then
    filtered according to the UUID.

    This is addressed by using an API (FindAllByUuid) which reads only
    the specific VM. When a VM is created the config spec will be updated
    with the UUID of the VM - that is, the field 'instanceUuid' will be
    set. The search is later done on this field.

    If the search fails then the old code will be invoked - this ensures
    backward compatibility with running VM's. Thus all VM's created
    without the 'instanceUuid' set will not be affected.

    In addition to optimizing the search we also cache the VM reference.
    This ensures that additional calls for the specific VM do not need
    to query the backend for the reference.

    Change-Id: I00d6c29f46b06d082cf3af0369a69147a3376341
    Closes-bug: #1258179