Given the logs there dont seems to be an abnormal behaviour here, this happens when one master reload after config gets updated, the other master then reload.
I would say it wont change much since IDO is being written in by icinga
Ok, thanks for confirming. This and the fact checks works for a short time after a reload makes me think your scheduler queue gets full. That leads me to ask you few other things.
How many Hosts/services are scheduled to run on each zone ?
You can get this information by doing an icinga2 daemon -C on a poller that belong to each different zone.
What is the MaxConcurrentChecks Value for each of zones ?
You can get this information by looking at constants.conf file, if not set it’s by default set at 512.
The idea is to see how many concurrent checks you can run vs how many services/hosts are scheduled to run by zone. By the way, even if MaxConcurrentChecks is slightly superior or equal to amount of service/hosts to check you can still have overdue checks if checks execution is too long.
Regarding this kind of problem i made this debug function which could help you too to get an overview of overdue checks.