It seems that caffeine project has the same issue:https://github.com/ben-manes/caffeine/issues/1468.

It seems that this problem has not a sure anwser. ConcurrentHashMap.computeIfAbsent or System.out.println maked the problem?

It is very strange in use.ConcurrentHashMap.computeIfAbsent is used high-frequency.

And there is a similar demo issue:https://www.reddit.com/r/java/comments/1512xuo/virtual_threads_interesting_deadlock/