Modern applications might need to support millions of users, but OS threading limits present a problem. Here's how Java 21 virtual threads solve it.

EventListenerProvider hooked to transaction while accessing userAttributes is causing ConcurrentModificationException #22902 ...

Caused by: java.lang.ArrayIndexOutOfBoundsException: 9 at java.util.LinkedList.toArray (LinkedList.java:1053) ~ [?:1.8.0_161] at java.util.LinkedList.addAll ...