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https://issues.apache.org/jira/browse/HBASE-5549?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13406977#comment-13406977
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nkeywal commented on HBASE-5549:
--------------------------------

It should be portable to previous branches. As it impacts multiple files there 
could be some conflict but this jira is quite self contained.

For the test part, reading the code you mentioned, yeah it could be :-). I 
don't see why it's failing however. Making zookeeper session expire is a kind 
of black art...
                
> Master can fail if ZooKeeper session expires
> --------------------------------------------
>
>                 Key: HBASE-5549
>                 URL: https://issues.apache.org/jira/browse/HBASE-5549
>             Project: HBase
>          Issue Type: Bug
>          Components: master, zookeeper
>    Affects Versions: 0.96.0
>         Environment: all
>            Reporter: nkeywal
>            Assignee: nkeywal
>            Priority: Minor
>             Fix For: 0.96.0
>
>         Attachments: 5549.v10.patch, 5549.v11.patch, 5549.v6.patch, 
> 5549.v7.patch, 5549.v8.patch, 5549.v9.patch, nochange.patch
>
>
> There is a retry mechanism in RecoverableZooKeeper, but when the session 
> expires, the whole ZooKeeperWatcher is recreated, hence the retry mechanism 
> does not work in this case. This is why a sleep is needed in 
> TestZooKeeper#testMasterSessionExpired: we need to wait for ZooKeeperWatcher 
> to be recreated before using the connection.
> This can happen in real life, it can happen when:
> - master & zookeeper starts
> - zookeeper connection is cut
> - master enters the retry loop
> - in the meantime the session expires
> - the network comes back, the session is recreated
> - the retries continues, but on the wrong object, hence fails.

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