[ZOOKEEPER-2126] Improve exit log messsage of EventThread and SendThread by adding SessionId

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.6.0
• Fix Version/s: 3.4.7, 3.5.1, 3.6.0
• Component/s: java client
• Assignee: Surendra Singh Lilhore
• Reporter: Zhihai Xu
• Created: 21/Feb/15 23:58
• Updated: 15/May/15 11:27
• Resolved: 15/May/15 04:16

Description

We saw the following out of order log when close Zookeeper client session.

2015-02-16 06:01:12,985 INFO org.apache.zookeeper.ZooKeeper: Session: 0x24b8df4044005d4 closed
.....................................
2015-02-16 06:01:12,995 INFO org.apache.zookeeper.ClientCnxn: EventThread shut down

This logs are very confusing if a new Zookeeper client session is created between these two logs. We may think new Zookeeper client session shutdown it EventThread instead of the old closed Zookeeper client session.

Should we wait for sendThread and eventThread died in the ClientCnxn.close?
We can add the following code in ClientCnxn.close.

sendThread.join(timeout);
eventThread.join(timeout);

with the change, we won't interleave old closed session with new session.
We can also create a new close API to support this so we won't affect the old code if people use old close API.