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Fixes #4956
The stack track included in the ticket indicates that a ConcurrentmodificationException occurred in Monitor.EventCounter:
This PR adds synchronization to several methods in the
EventCounter
class to avoid this from happening again.Another approach that would probably work would be to make the 3 collections in this class thread safe by making the HashMaps into ConcurrentHashMaps and the HashSet into a
Collections.synchronizedSet(new HashSet<>())
. That would function just fine in the current code as far as I can tell but if we would ever need to iterate over thesynchronizedSet
, we would need to use asynchronize
block anyways so i figured just making the methods themselves synchronized would future proof and fix the current issue too.