Heal instance info cache causes high extra DB queries

[Brian Elliott]

_heal_instance_info_cache currently does not load system_metadata. As a result, the calls into _get_instance_nw_info end up lazy loading the data via obj_load_attr() when checking for the presence of system metadata.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/46095

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/46095
Committed: http://github.com/openstack/nova/commit/e0931d718393e1bc2dd6164c1b08daccd5a12644
Submitter: Jenkins
Branch: master

commit e0931d718393e1bc2dd6164c1b08daccd5a12644
Author: Brian Elliott <email address hidden>
Date: Mon Sep 9 22:43:46 2013 +0000

    Reduce DB load caused by heal instance info cache

    Load system metadata with instance fetches in the
    _heal_instance_info_cache periodic task. This will eliminate
    DB queries to lazy load the system metadata in _get_instance_nw_info.

    (lazy loading happens in the Instance object's obj_load_attr method)

    bug 1223969

    Change-Id: I835fc73ef3a92885cec174e1533db10e28752fe1

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/47615

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/47615
Committed: http://github.com/openstack/nova/commit/ce385ca3912d92fe446a46682080d6b342b8d91b
Submitter: Jenkins
Branch: master

commit ce385ca3912d92fe446a46682080d6b342b8d91b
Author: Chris Behrens <email address hidden>
Date: Fri Sep 20 18:23:48 2013 +0000

    Actually fix info_cache healing lazy load

    system_metadata is still being lazy loaded as a part of healing the
    instance info_cache. A previous attempt to fix this issue missed the
    more important call.

    It's actually more efficient to not load the system_metadata when getting
    the list and allow the 1 instance to lazy load. For the cached instances,
    we will ask for system_metadata when getting a fresh copy from the DB.

    Fixes bug 1223969

    Change-Id: Ib95e868135ed2b36af7ddbcfb8d5905bfe14d1fe