Before Creating the Enhancement Request

• I have confirmed that this should be classified as an enhancement rather than a bug/feature.

Summary

change the type of delayLevelTable from ConcurrentHashMap to ConcurrentSkipListMap

Motivation

Iterating map variable "delayLevelTable" in order should be JDK-independent. ConcurrentHashMap does not provide guarantee iterating keys in orders. Though iterating ConcurrentHashMap<Integer, Long> is by order due to implementation of ConcurrentHashMap, it should be jdk-independent.

Describe the Solution You'd Like

change the type of delayLevelTable from ConcurrentHashMap to ConcurrentSkipListMap

Describe Alternatives You've Considered

none.

Additional Context

No response