What to know if we can prevent multiple schedulers from firing when the server is down and then restarted?
In our case we are using End User Reporting module, which has a time interval based Scheduler which runs every 15 mins. Our application servers are down outside office hours. If there is an notification schedule during the outage time, then on server startup the notifications get sent out 100 or more times, due to all the missed schedulers firing again on startup.
For the fixed time schedulers we have used Advanced Condition on the timer to fix this problem. But we cannot use the same for a time interval based scheduler.
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The solution I found for this was to write to a table using this plugin: Pessimistic Locking and skip the node if it was already locked. I may write a more detailed post on my blog on this subject at some point if there is interest.