[jira] [Commented] (HBASE-7334) We should expire the zk session for crashed servers rather than deleting ephemeral znodes

["Andrew Purtell (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HBASE-7334?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13529592#comment-13529592 ] 

Andrew Purtell commented on HBASE-7334:
---------------------------------------

See also ZOOKEEPER-829. 
                
> We should expire the zk session for crashed servers rather than deleting ephemeral znodes
> -----------------------------------------------------------------------------------------
>
>                 Key: HBASE-7334
>                 URL: https://issues.apache.org/jira/browse/HBASE-7334
>             Project: HBase
>          Issue Type: Improvement
>          Components: master, regionserver, Zookeeper
>    Affects Versions: 0.96.0
>            Reporter: Enis Soztutar
>
> For faster recovery HBASE-5844 and HBASE-5926 added logic to delete the ephemeral znodes for the master and region server from the hbase-daemon.sh script. However, the master and RSs have other ephemeral nodes that are not cleaned (for example region splitting, table lock)
> Instead of deleting the main znode, we can just invalidate the zookeeper session by doing smt like HBaseTestingUtility.expireSession(). 
> For this we need to keep the zk.getSessionId() and zk.getSessionPasswd() around(write to a local file), keep the file updated for reconnections, and once we know that the zk session is gone in ZNodeClearer, we can just create a new session with the same credentials, and close that one, effectively causing zk to delete all ephemeral nodes for the session. 

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