Comment 4 for bug 1819473

Reviewed: https://review.openstack.org/649713
Committed: https://git.openstack.org/cgit/openstack/stx-fault/commit/?id=7ae75e24c8c425bb1b2741a55d203c5069072990
Submitter: Zuul
Branch: master

commit 7ae75e24c8c425bb1b2741a55d203c5069072990
Author: Eric MacDonald <email address hidden>
Date: Wed Apr 3 15:50:41 2019 -0400

    Protect FM API shared data with thread locking

    Collectd runs all its python plugins concurrently.

    With the expansion of collectd python plugins due
    to the obsolesence of rmon collectd core dumps are
    being reported during collectd startup when the FM
    service on the controller is not running.

    Debug of the issue revealed that the core dumps are
    due to having no mutex around FM API's shared data.

    The required mutex is provided by this update by
    adding a while locked expression to the start of
    each API.

    Also fixed 3 pep8 errors.

    Closes-Bug: 1819473

    Test Plan:
    PASS: Test before and after cases to confirm that without
          the change we see core dumps but with the change the
          API and collectd plugin behavior is correct without
          the core dumps.
    PASS: System install with current collectd plugins and fm's
          python API enhanced with locking.
    PASS: Have sm stop managing the fmManager process, kill it
          and then restart collectd over and over.
          Should not see any collectd core dumps.
    PASS: Verify nfv alarming still works

    Change-Id: I3d5ef0bd9cb774299b4c0f3b9e33cddb7c0f776c
    Signed-off-by: Eric MacDonald <email address hidden>