Comment 8 for bug 1960006

Reviewed: https://review.opendev.org/c/openstack/neutron/+/828758
Committed: https://opendev.org/openstack/neutron/commit/d67b05ddea02dbe5d7a0563fa2f37f472c945e40
Submitter: "Zuul (22348)"
Branch: stable/xena

commit d67b05ddea02dbe5d7a0563fa2f37f472c945e40
Author: Daniel Alvarez Sanchez <email address hidden>
Date: Fri Feb 4 11:32:47 2022 +0100

    [ovn] Prevent stale ports in the OVN database

    Under a lot of load, there can be situations where all the Neutron
    workers have not updated their in-memory copy of the NB database
    in time before certain operations.

    This scenario can lead to stale resources when a somewhat recently
    created port is attempted to be deleted, but the worker handling
    this deletion doesn't know about the OVN port yet.

    This patch detects this condition and allows some time (at least one
    maintenance task cycle) before it deletes the OVN revision number.
    If the port then shows up in the OVN database within that window, then
    it will be deleted later by the maintenance task avoiding the stale
    ports. If not, the revision number row will be deleted and we won't
    stale these entries either.

    Closes-Bug: #1960006
    Signed-off-by: Daniel Alvarez Sanchez <email address hidden>
    Change-Id: Ie4093dc6cd63b89e3a62363a4f805ef8287d15b9
    (cherry picked from commit be7331c8169c53e3900c9c1a08e12808cf5ed2ec)