Comment 6 for bug 1700875

Reviewed: https://review.openstack.org/489075
Committed: https://git.openstack.org/cgit/openstack/ceilometer/commit/?id=40b36e0e2e075ff796603fd1f89a36524e8f616f
Submitter: Jenkins
Branch: stable/ocata

commit 40b36e0e2e075ff796603fd1f89a36524e8f616f
Author: xianbin <email address hidden>
Date: Wed Jun 28 11:13:02 2017 +0800

    Fixed ceilometer arithmetic transformer bug

    For the arithmetic transformer, when some thread use method _update_cache()
    to update self.cache, and the same time the flush() method may be invoke
    self.cache.pop(res_id) and raise "RuntimeError: dictionary changed size
    during iteration"

    Change-Id: I3ea89c7d3bfbdb661770b5d478188f8723c17716
    Closes-bug: #1700875
    (cherry picked from commit 91d11e7c7915fe8806af3e19064af0cd71b8fe76)