Comment 15 for bug 1938766

Reviewed: https://review.opendev.org/c/openstack/neutron/+/808864
Committed: https://opendev.org/openstack/neutron/commit/be6872be5a8b59c0eba222879404a2803c7e441d
Submitter: "Zuul (22348)"
Branch: stable/victoria

commit be6872be5a8b59c0eba222879404a2803c7e441d
Author: Terry Wilson <email address hidden>
Date: Wed Sep 1 14:19:19 2021 +0000

    Fix neutron_pg_drop-related startup issues

    There is a python-ovs bug that allows transactions to be executed
    before it has started monitoring the db for changes. This breaks
    ovsdbapp's AddCommand behavior, which looks up a row in memory
    post-commit to return it to the caller, because we process the
    reply from ovsdb-server that has the UUID in it, but when we try to
    look it up in memory, it isn't there since that is handled via the
    monitor notifications.

    Since we don't care about the return value, we can just ignore the
    KeyError. In addition, the request to Idl.cond_change() to monitor
    only the neutron_pg_drop table was failing for a similar reason--
    it is called before the initial monitor request is sent, so
    directly setting table.condition will allow the condition to be
    added to the initial monitor request.

    Conflicts:
      neutron/plugins/ml2/drivers/ovn/mech_driver/ovsdb/ovsdb_monitor.py

    Closes-Bug: #1938766
    Change-Id: I78af15970a86923fb810e903d38634b6e60a8fe4
    (cherry picked from commit 76ee64f4a8095ba207872d5de9613f93f208fdd4)