currently, if we have multiple event alarm evalutors, there might be some race conditions in the following scenario: 1. ceilometer-notification-agent gerated 2 events of the same type in sequence, but with different traits, the 1st one would trigger the alarm, and the 2nd one won't, it then send the 2 events to aodh alarm evaluators 2. if there're multiple aodh alarm evaluators, it's possbile that the 2nd event would be processed before the 1st one, in that case, the alarm status in the DB might not be consistent, depends on the sequence of how the events are being evaluated
