Comment 2 for bug 1583992

Reviewed: https://review.openstack.org/319765
Committed: https://git.openstack.org/cgit/openstack/dragonflow/commit/?id=6062a431707229426e0c3454f0df146b2046c622
Submitter: Jenkins
Branch: master

commit 6062a431707229426e0c3454f0df146b2046c622
Author: duankebo <email address hidden>
Date: Mon May 23 08:18:00 2016 +0000

    Limit the frequency of db sync

    If exception occurs when processing a northbound event, one second delay
    will be introduced by db sync, it leads to more exceptions because of
    the delay. Avalanche will occur then. This patch limits the frequency of
    db sync by one time every three minutes at maximum.

    Closes-Bug: #1583992

    Change-Id: I2f2635467b8fc5ab816ea4ac355e3e1cc488d5a2