[jira] [Created] (HBASE-8539) Double(or tripple ...) ZooKeeper listeners of the same type when Master recovers from ZK SessionExpiredException

["Jeffrey Zhong (JIRA)" <ji...@apache.org>]

Jeffrey Zhong created HBASE-8539:
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             Summary: Double(or tripple ...) ZooKeeper listeners of the same type when Master recovers from ZK SessionExpiredException
                 Key: HBASE-8539
                 URL: https://issues.apache.org/jira/browse/HBASE-8539
             Project: HBase
          Issue Type: Bug
          Components: master
    Affects Versions: 0.95.0, 0.94.7, 0.98.0
            Reporter: Jeffrey Zhong
            Assignee: Jeffrey Zhong


When Master tries to recover from zookeeper session expired exceptions, we don't clean old registered listener instances. Therefore, it may end up we have two(or more) listeners to double handling same events. Attached a screen shot from debugger to show the issue.

I considered to limit one listener per class while I think that would limit the listener usage so I choose to clear exiting listeners during recovery for the fix.

(This issue is unrelated to the issue HBASE-8365 because I verified there is no dup-listeners when HBASE-8365 happened)

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