Comment 13 for bug 1777968

Reviewed: https://review.openstack.org/583527
Committed: https://git.openstack.org/cgit/openstack/neutron-lib/commit/?id=ed62a06a536a39b1236bd4dcadb2dd13cc2c4b4b
Submitter: Zuul
Branch: master

commit ed62a06a536a39b1236bd4dcadb2dd13cc2c4b4b
Author: LIU Yulong <email address hidden>
Date: Mon Jul 16 09:56:47 2018 +0800

    Make the DB retry mechanism more robust

    Currently in the worst case retry interval is:
    [0.1, 0.2, 0.4, 0.8, 1.6, 3.2, 6.4, 10, 10, 10]
    This may cause some neutron DB action fail, and result an
    API 500/40X error, for instance, the IP allocation get a
    large failure chance with such config.

    After this change, the worst case retry interval will look
    something like this:
    [0.5, 1, 2, 4, 8, 10, 10, ... 10]

    So, for the new value 20 and 0.5, in the worst case the total
    time cost will be 165.5s. For the old config, it's 42.7s. It's
    not too radical for the new retry input params. And we get a
    higher rate of API success.

    Change-Id: I5ad139bdfb3ae125658b36d05f85f139a1b47bee
    Closes-Bug: #1777968