I get loads of these in the logs.
2019-08-11 18:43:18.689 [WARN ] [me.core.internal.events.EventHandler] - Dispatching event to subscriber 'org.eclipse.smarthome.io.monitor.internal.EventLogger@155fd69' takes more than 5000ms.
2019-08-11 18:41:48.579 [ERROR] [org.quartz.simpl.SimpleThreadPool ] - Worker thread was interrupt()'ed.
java.lang.InterruptedException: null
at java.lang.Object.wait(Native Method) ~[?:?]
at org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:568) [107:org.eclipse.smarthome.core.scheduler:0.10.0.oh240]
I get them when I have a particular rule running under cron. It fires every minute and will, on occasion, cause this. Each time one of these appears in the logs I lose a quartz thread. When the count of these exceptions matches the number of threads then no cron rules will run.
I’ve tried for a long time to work around it and seek help but it seems very specific to me and my setup (It has to do with the Xiaomi binding.) I cannot create a working example for others to try and debug 
My solution:
Using wget, in a cron job, call the rest API for an item every minute. When that item changes to ON the rule fires. It’s a hack but it works.
Setting logs to debug for quartz:
log:set DEBUG org.quartz.core
Other threads where I have talked about it: