The simplest reproducer is running introspection on only one node, waiting for the finish, then running again on the same node.
ironic-inspector 2.2.6 was released upstream with the fix for this bug. I think we should update.
Manual installed openstack-ironic-inspector-2.2.6-1.el7ost.noarch and repeatedly Run introspection for 10 time on the same nodes. All introspections pass with no errors
Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory, and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. https://access.redhat.com/errata/RHBA-2016:1229
The needinfo request[s] on this closed bug have been removed as they have been unresolved for 1000 days