Comment 9 for bug 1788556

Reviewed: https://review.openstack.org/604321
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=04b7f80f999c0fec456f5e905ce9407ab9ec5261
Submitter: Zuul
Branch: stable/pike

commit 04b7f80f999c0fec456f5e905ce9407ab9ec5261
Author: aojeagarcia <email address hidden>
Date: Wed Aug 22 10:41:14 2018 +0200

    Parse dhcp leases file in a more robust way

    It turns out that in environments with a big number of VMs, sometimes
    the neutron dhcp agent fails to read the dhcp lease file because some
    lines with the ipv4/ipv6 entries don't have enough fields and causes the
    dhcp agent to fail.

    When this happens the agent calls sync_state to
    fully resync the agent state, that causes a serious performance problems
    in scale environments.

    We need to be more robust reading the file to handle these exceptions.

    Co-authored-by: stephen-ma
    Partial-Bug: #1788556

    Change-Id: Ia681a5e929df5bf8c97ae9445876c306c34061b5
    (cherry picked from commit 8a3ff8a19ec39630d24b71cec86740b6b9f16bbe)