Github user lvfangmin commented on the issue:
https://github.com/apache/zookeeper/pull/665
Yes, it's similar to ZOOKEEPER-1669, which uses sessionMap to reduce the
cost of close session, most of the code are identical as well.
In 3.4, it has the removeCnxn method defined in NettyServerCnxnFactory
while it keeps the same logic in NettyServerCnxn.close() in 3.6, I'll leave it
as is for now, given that it's not quite relative to this Jira and this diff is
already ready to land.---
