Comment 5 for bug 1818914

Reviewed: https://review.opendev.org/641521
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=54877e06f13b13134f2030557cd779f947a43c24
Submitter: Zuul
Branch: master

commit 54877e06f13b13134f2030557cd779f947a43c24
Author: Matt Riedemann <email address hidden>
Date: Wed Mar 6 18:46:22 2019 -0500

    Add functional recreate test for bug 1818914

    The confirm resize flow in the compute manager
    runs on the source host. It calls RT.drop_move_claim
    to drop resource usage from the source host for the
    old flavor. The problem with drop_move_claim is it
    only decrements the old flavor from the reported usage
    if the instance is in RT.tracked_migrations, which will
    only be there on the source host if the update_available_resource
    periodic task runs before the resize is confirmed, otherwise
    the instance is still just tracked in RT.tracked_instances on
    the source host. This leaves the source compute incorrectly
    reporting resource usage for the old flavor until the next
    periodic runs, which could be a large window if resizes are
    configured to automatically confirm, e.g. resize_confirm_window=1,
    and the periodic interval is big, e.g. update_resources_interval=600.

    This change adds a functional recreate test for the bug which will
    be updated in the change that fixes the bug.

    Change-Id: I4aac187283c2f341b5c2712be85f722156e14f63
    Related-Bug: #1818914
    Related-Bug: #1498126